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May 31st, 2022 Uta McKelvy, Extension Field Crop Pathologist

Quick Summary for Busy People

  • Physiological leaf spots are caused by chloride deficiency. Fungicide applications are not effective, but chloride fertilizer can help.
  • Fungal leaf spots may occur where wet and cool weather is observed. Fungicide applications are effective but may not necessary, depending on the crop growth stage.
  • Take the time to diagnose/get diagnosed the leaf spot cause before you make treatment decisions.

I've seen several winter wheat samples, mainly variety Bobcat, with tan spot-like symptoms in the Schutter Diagnostic Lab. These leaf spots turned out to be Physiological Leaf Spots (PLS). PLS are not caused by a (fungal) pathogen, which also means that fungicide applications will not be effective. Distinguishing between fungal leaf spots and PLS is difficult but important. This AgAlert discusses differentiation, characteristic symptoms, risk factors, and treatment options for PLS and fungal leaf spots on wheat and includes resources on fungicide applications.

Differentiation between Physiological and Fungal Leaf Spots - a "quick and dirty" key (by Mary Burrows)

  1. Physiological spots occur on all leaves, not just in the thicker, lower canopy.
  2. Physiological spots are more uniform than fungal spots (there aren't more spots on lower leaves than upper leaves).
  3. Physiological spots are not highly associated with patches of residue in the field, it is more uniform across the field.
  4. Physiological spots have a very sharp edge to teh lesion, whereas fungal spots are more fuzzy and continue to expand over time.
  5. Fungal spots, when left in a moist chamber 24-48 h, develop small black or brown spots that are fungal structures call Pyncidia. Physiological spots do not form pyncindia. You can see these under high humidity in the field with a 10-20x lens.
  6. Look on residue for black pycnidia - these are the source of fungal leaf spots. If there are non, it might be physiological.

Read on below for more details on Physiological and Fungal leaf spots and treatment options.

Physiological Leaf Spots (PLS)

Certain winter wheat varieties are more prone to PLS. Bobcat develops PLS, and other varities are known to develop PLS as well, for example CDC Falcon, Raptor, Peregrin, Promontory, and others. Please note that Bobcat has been performing very well throughout its development process at MSU, even in the presence of PLS.

PLS symptoms typically appear from flag leaf emergence to boot stage, but I have seen plants at earlier growth stages developing PLS this spring. PLS appear as circular to oblong, dark brown or chlorotic lesions and the tissue in the center looks bleached, white to grey in color. The lesions are often surrounded by narrow chlorotic (yellow) halos and tend to be more numerous toward the tip of the leaf blade. PLS lesions have a more discrete margins compared to fungal leaf spots, which are more diffuse and continue to expand over time. Most importantly, PLS do not develop small black spots in the center of the lesions when kept in a humid environment for 24-48 hours.

PLS are often caused by chloride deficiency. Low chloride uptake by the plants could occur in sandy soil with high rainfall because the chloride has leached, but also in droughty soils where root growth is reduced. If you want to rule out or rule in chloride deficiency. I suggest you do a tissue test for chloride concentration. The suggested critical level in plant material (entire plant) is between 0.1 and 0.4% with large yield increases and leaf spot decreases when chloride was applied at tissue chloride concentrations below 0.1%. Applying 10-20 lb potash (0-0-60) per acre should be sufficient (5-10lb Cl/acre and 12 lb K2)/acre) to mitigate chloride deficiency. Alternatively, a similar amount of chloride can be applied as a liquid (for example calcium chloride or ammonium chloride). Dry fertilizer applications can be applied at any time through the late jointing stage, depending on sufficient rain (or irrigation). Liquid formulations can be applied to the foliage up to the time of flag leaf emergence.

Please note that the Schutter Diagnostic Lab does not offer tissue analysis or soil testing services but most independent labs test for chloride.

Please contat Clain Jones (phone (406)994-6076 email [email protected]) for questions on tissue testing and fertility recommendations.

Fungal Leaf Spots: Tan Spot, Septora Tritici Blotch, Stagonospora Leaf Blotch

Fungal leaf spots on Montana wheat include Tan spot, Septoia tritici blotch, and Stagonospora leaf spot. These diseases are residue borne. Tight cereal rotations and high residue cover are factors that promote fungal leaf spots. Fungal leaf spots are more concentrated in the lower canopy, which is closer to the residue (source of inoculum) and where it is more humid. Wet and humid weather favors fungal leaf spot diseases. Septoria tritici blotch develops at cool temperatures of 59-68oF. In other words, if you live in a part of Montana that has experienced a lot of precipitation lately while temperatures are still cool, fungal leaf spot diseases are to be expected.

Fungal Leaf Spot Symptoms

Tan spot is caused by Pyrenophora tritici-repentis. Initial symptoms will be small, brown leaf spots that enlarge and develop tan necrotic spots surrounded by yellow halos. The lesions are initially oval and take on a diamond shape as they enlarge. When kept in a humid environment, a pinhead-sized black spot will develop in the center of the lesion.

Septoria tritici bloch is caused by Zymoseptoria tritici. The disease starts out as tan to brown lesions on the lower leaves, which have an elliptical to rectangular shape and form between leaf veins. The lesions enlarge and their centers become necrotic. Dark fruiting bodies will develop in the lesions, giving them a speckled appearance (as if sprinkled with cracked peppercorns).

Stagonospora leaf blotch is caused by Stanonospora nodorum. The disease may first become evident on the lower leaves as small yellow spots. The spots will enlarge into elliptical, lens-shaped lesion of gray or brown color and will be surrounded by yellow margins. In the center of the lesions, you may observe small, brown dot-like structures, which are called pycnidia. The lesions can coalesce to form large areas of brown, necrotic tissue on the leaves.

Fungicide applications are effective at managing fungal leaf spots. I strongly recommend you bring a sample to your local Extension agent or sumbit one to the Schutter Diagnostic Lab for diagnosis before you plan a fungicide application. If you send a sample into the clinic for confirmation, please let us know if you've already applied a fungicide - if you have, it's unlikely we will be able to recover spores.

With a fungicide application, protecting the flag leaf from disease if key. You can find resources on fungicide use, application decisions, and suitable modes of action below. Varieties that are less susceptible to leaf spot pathogens are available. Areas with high cereal residue cover are likely disease hot spots and can be managed by practices of residue decomposition and removal. Crop rotation is also effective.

Powdery Mildew

I have also heard reports of powdery mildew on the winter wheat crop, so I thought I include some info on that while we're at it.

Powdery mildew lesions are sporulating on lower leaves and may have an orangish cast. The lesions are defined and powdery, not in stripes. This is NOT stripe rust. Powdery mildew starts out grey or white and forms hard black pinprick sized spores called cleistothecia further along in disease development. Disease development is optimal between 59 - 72oF and is significantly reduced above 77oF. The disease prefers high humidity but does not prefer active rainsplash. If symptoms are on lower leaves only, no treatment is recommended. If the temperatures warm and it becomes dry, it's likely the disease will dry up too. If symptoms start moving up the crop and the weather remains favorable, a fungicide may be recommended depending on the yield expectation of your crop and whether it's irrigated or not. All varieties should be considered susceptible in Montana.

Where you can find more information

Physiological Leaf Spots:

Fungal Leaf Spots and other wheat diseases:

Resources on Fungicide use (decision) and suitable modes of action:

(View Pictures)

Figure Captions

Figure 1. Physiological leaf spot symptoms on winter wheat variety Bobcat at early jointing (left) and boot stage (right). Photo credit: Uta McKelvy, Montana State University.

Figure 2. Leaf spot symptoms associated with tan spot (left), Septoria tritici blotch (middle), and Stagonospora leaf blotch (right). Photo credit: (left) Mary Burrows, Montana State University; (middle) Jack Kelly Clark, UC IPM Program; (right) Paul Bachi, University of Kentucky.

Figure 3. Islands of fuzzy, powdery growth on a wheat leaf associated with powdery mildew. Photo credit: Mary Burrows, Montana State University.


Please don’t hesitate to email ([email protected]) or call (406-994-557) if you have any questions. I’m here to help.


Uta McKelvy, Extension Field Crop Pathologist

May 26th, 2022 - Abiya (Abi) Saeed - Extension Horticulture Specialist ([email protected])

It is that time of year again, and the Schutter Diagnostic Lab has been receiving several samples of evergreen trees and shrubs with symptoms of winter injury/winter burn, including evidence of browning needles and branches. These symptoms can appear without warning in the spring, and can seem very alarming, though many trees will often grow out of it, especially if take care of by watering and watching for new growth.

This is a cultural/environmental issue:

Resulting from minimal winter snow cover, extended periods of low humidity, and spring temperature fluctuations; narrow and broad-leaved evergreens (especially spruce, Douglas-fir and pines) are subject to drying out, especially if supplemental irrigation is not applied to the plants during the fall months. This results from the plants continuing to lose moisture through transpiration at a rate faster than it can be replenished. Common symptoms include red, yellow or brown discoloration of foliage, especially on need tips, and can sometimes affect entire branches. Damage is more pronounced on the south and south-west sides, and can also cause damage to roots which can further impact their ability to replace lost moisture.

Damage can be more severe in areas with high wind exposure, during periods of large fluctuation between daytime and nighttime temperatures, and on younger/newly transplanted trees and shrubs without well-established root systems.

These symptoms, although they appear alarming, will be less obvious as soon as the tree pushes the new growth and/or drops its dead needles. As long as the buds are soft and green (as they are in this case), there is still good growth and life in the tree. It is important to make sure your trees are watered thoroughly and regularly during dry periods, especially into the fall.

Please open the following links for information about caring for stressed trees:

Helping Trees to Manage Stress

Simple Steps to Aid Stressed Trees (PDF)

May 27th, 2022 - Uta McKelvy, Extension Field Crop Pathologist (406)994-5572 [email protected]

Crop samples are starting to come into the Schutter Diagnostic Clinic and my phone is buzzing a lot more these days. Thank you all for reaching out! This year's cold spring is giving our crops a slow start and a lot of waht i see in the diagnostic lab is related to cold temperatures and nutrient deficiencies. This AgAlert includes a summary of what to look out for these days.

Quick Summary for Busy People

  • This spring has been unsually cold, which is slowing plant growth. Be patient.
  • Color banding is a common symptom of freeze injury in spring-sown seedlings. Burned leaf tips and bleached, wilted-looking leaves (or leaf sections) are also typical. Depending on the crop growth stage, temperature low and duration of low temperatures, the damge from cold/freeze injury may range form cosmetical to yield-limiting.
  • Cold soils limit nutrient uptake. We've seen symptoms of nitrogen, iron, and zinc deficiency. Nutrient deficiency could further be compounded by root rot issues.

1. Cold injury/stress

This spring has been quite cold and crops are slow to resume growth. I have received questions on alfalfa not resuming growth this spring. I heard reports on spring sown ceral crops looking stunted and yellowish, sometimes having twisted leaves. While there may be other reasons, the cold temperatures and cool soils are certainly slowing crop progress. Plant nutrient acquisition is limited in cool soils, which is why crops may appear nutrient deficient. Have a little patience. The plants should grow out of it once the soil warms up. Following is a discussion of more specific cold and freeze injury symptoms by crop and developmental stage.

Wheat: Freezing temperatures during the spring may cause color banding on spring-sown seedling when warm days are followed by cool nights. You may observe yellow, white, brown, or even purple bands on the young leaves, which often occur at the same height on neighboring seedlings. Freezing temperatures can also cause leaf tips to turn yellow and necrotic. These types of injury are cosmetic and the plants will grow out of it. During stem elongation, cold temperatures may damage the stem and cause it to split or cause damage to the vascular system (water and nurient transport), which will cause teh stem to collapse and lodge. The damaged area on the stem may be bleached and water-soaked. The growing point or spike may be damaged with few symptoms on the stem. The emergence of chlorotic as the culm deteriorates. Emerging heads may be trapped or may have "frosted tips" (Pun intended! Couldn't help it.) Don't confuse frost tipped heads with head blight. Further information on freeze injury symptoms in wheat can be found in the publication from Kansas State University "Spring Freeze Injury to Kansas Wheat", including a neat table of primary symptoms of freeze injury to wheat at spring growth stages and its effect on yield.

Barley: Frost damage during stem elongation can damage the developing heads and resulting in shriveled, deformed, and pale heads. More information on freeze injury symptoms in barley (and oats) can be found in the "Frost Identification guide for cereals" published by the Government of Western Australia Department of Primary Industries and Regional Development and the Grains Research and Development Corporation.

Pulses: One of the most obvious symptoms of freeze injury to young pea plants is the death of the growing point. The most recognizable symptom of freeze injury on pea leaves is the death of interveinal tissue, which appears water-soaked at first and then turns necrotic brown. Chickpeas are generally more sensitive to freeze injury than lentils. From a distance, the top leaves of injured plants turn yellow to white and appear dry. Sometimes only the leaf margins dry up and appear scorched without developing lesions of definite shape or size. More information on freeze injury symptoms in pulse crops (canola, and lupine) can be found in the "Frost Identification Guide for Canola and Pulses" published by the Government of Western Australia Department of Primary Industries and Regional Development and the Grains Research Development Corporation.

2. Nutrient Deficiency

The cold soils make it difficult for plants to acquire nutrients. You may see stunted plants that look pale green or yellow. Chlorotic (yellow) leaves can indicate nitrogen deficiency, which first expresses at the older (lower) leaves, moving from the leaf tips to the base. Iron deficiency causes yellow leaves with green stripes along the leaves' length and could be confused with virus infection. Zinc deficiency expresses very similar to iron deficiency. Iron deficiency is very common in high pH soils. Folliar applications of nutrient solutions containing iron may be beneficial, but the plants usually recover just fine once they start growing. Leaf yellowing and stunted plant growth could also be caused by root rots, and often we observe compounding effects of two or more factors.

View alert and pictures

Picture Captions

Figure 1. Twisted leaves (left) and yellowing and necrotic leaf tips (right) due to cold injury. Picture courtesy Mary Burrows, Montana State University.

Figure 2. Freeze injury to young pea plant. The leaves are scorched and dead. Picture courtesy Mary Burrows, Montana State University,

Figure 3. Evenly yellowing leaves from the leaf tip to the base with older leaves being affected first is an indicator of nitrogen deficiency (left). Yellow leaves with prominent green veins are a symptoms of iron or zinc deficiency (right). Picture courtesy (left); (right) Juliet Marshall, University of Idaho.

May 25th, 2022 - Kevin Wanner

The next two weeks are a good time to scout for wireworms. Wireworm treatments after crop emergence are not available, but wireworms tend to persist in the soil for several years after they have established. Scouting now to identify infested fields informs seed treatments that may be required next spring season.

Wireworms are a soil insect pest that feed on seeds and the roots and stem of developing seedlings. They can infest many different crops but are most common in continuously cropped spring wheat fields. Look for thin patchy areas during stand development. Wireworms can be found by digging around the roots of symptomatic plants (cutworms can also cause stand thinning damage).

Attractive baits can be placed in the field to attract wireworms. Half a cup of grain can be placed in a foot stocking, soaked overnight to help with germination, and burried 6-8 inches deep in the field. The "bait bag" can be removed after the seed germinates in 7-14 days. Wireworms will be found in and around the bait trap.

A PDF file with instructions can be found at the following link (note: covering the trap with black plastic is optional):

Wireworm Scouting: The Shovel Method and the Modified Wireworm Solar Bait Trap (PDF)

May 16th, 2022 - Hayes Goosey

"Hello all,

As we enter the 2022 growing season, keep in mind the MSU Extension Wildfire and Drought Taskforce has made substantial changes to our web page with new information and updates to existing information. Much of Montana's dryland production areas are still experiencing moderate to extreme drought. Consult our web page for timely and relevant information as always, reach out to us with suggestions."

MSU Wildfire and Drought web page

May 12th, 2022 - Kevin Wanner

After a few years of high grasshopper populations many are eager to start spraying this spring. Vigilant scouting is important during grasshopper outbreaks - pesticides applied too early or too late are likely to be ineffective. Control measures should not be applied until the grasshoppers have hatch or their numbers can be estimated.

Egg hatch can begin during May and can continue through the summer, but timing depends on the species of grasshopper and the weather. David Branson (USDA - ARS Sidney) suggests the grasshopper hatch this year could be delayed by a week or two due to the cool spring weather (unless the upcoming weather becomes warmer than average).

For rangeland grasshopper control, Gary Adams (USDA - APHIS Billings) indicates that optimal timing coincides with the 2nd and 3rd instar stages. Typically, rangeland treatment in Montana occurs during the 2nd to 3rd week of June but could be delayed this year. Specific timing  depends on weather and is based on scouting and staging the grasshopper population.

For grasshopper control in crops, I do not recommend spraying before most of the eggs have hatched and the pest numbers can be counted. Sprays applied before egg hatch will not have sufficient residual activity. Juvenille and adult grasshoppers can migrate into crops from surrounding grassland, regular scouting is advised through the summer.

Treatment thresholds are based on the number of grasshoppers per square yard. The square foot method of surveying grasshoppers; The number of grasshoppers in a one square foot area is estimated visually and reandomly repeated 18 times while walking a transect. The total number of grasshoppers is tallied and divided by two to give the number per square yard. Alternatively, four 180-degree sweeps with a 15-inch diameter sweep net is considered equivalent to the number of adult (or nymph) grasshoppers per square yard (NDSU Extension).

For more information on scouting methods, threshold and insecticides in rangeland and crops, refer to the High Plains IPM Guide:



Small Grains


Quick Summary for Busy People

  • We observe prime conditions for Pythium seed and seedling rot; high soil moisture and cool soil temperatures
  • Use fungicide seed treatments with mixed modes of action including Metalaxyl, Mefenoxam, or Ethaboxam for spring crops not yet planted
  • Delay planting of highly susceptible crops, especially Kabuli-type chickpeas, until soils have warmed up to above 50oF. Use disease free-seed with maximum vigor

Spring has sprung and planting is in full swing.The snowstorms and rain events in the past days and weeks brought some much-needed moisture to the state. But the newly received soil moisture in combination with still cool soil temperatures create prime conditions for seed and seeding rot caused by Pythium. Pulse crops are at high risk.

What is Pythium rot?

Favorable Conditions: Pythium is a soilborne water mold (Oomycete) that causes seed rot and pre- and post-emergence damping-off on a wide range of host platns. Pulse crops are at high risk. The pathogen is favored by high soil moisture and low to moderate soil temperatures (50 to 75oF). The risk of seedling damping-off is especially high when soils are saturated for one or more days after planting and before emergence. Low-lying areas in the field, where water accumulates, are likely disease hot spots. High residue cover, that keeps soil temperatures cool, also favors the disease.

Symptoms: Poor stand establishment and yellow seedlings are initial indicators of seedling damping-off. These symptoms often occur in circular patches in the field and may be more noticeable in low-lying areas. The root system of affected seedlings is poorly developed with a lack of fine root hairs. Roots often show brown discoloration and have a gelatinous texture. The root cortex (outer layer of the root) can easily be stripped away, exposing the root core.

Susceptible crops: Pythium has a wide host range, including small grain crops, alfalfa, and many weed species. Pulse crops are very sensitive to seed, seedling, and root rot diseses caused by this pathogen. Pythium is the most frequently reported cause of seed and seedling rot in peas. Kabuli-type chickpeas are much more susceptible than the Desi-type. Low-tannin cultivars of lentil with light-colored seeds are more susceptible than dark-colored seed cultivars.

How can I manage Pythium root rot?

Fungicide seed treatments are strongly recommended for pulse crops. Choose a seed treatment product with mixed modes of action to ahcieve broad-spectrum protection against a variety of soilborne seed and seedling pathogens. Fungicides active ingredients with efficacy against Pythium (Oomycete, not a true fungus) include Metalaxyl, Mefenoxam, and Ethaboxam. At least one of these active ingredients should be included in your fungicide treatment to provide protection against Pythium. VibranceMaxx Pulses is one suitable product with efficacy against Pythium and other seed- and soilborne diseases. View updated Fungicide Seed Treatment Table for Pulse Crops for the 2022 growing season which provides an overview of suitable seed treatment options. You may also refer to the North Dakota Field Crop Plant Disease Management Guide for seed treatment options in pulses and other crops.

Delaying seeding dates of highly susceptible crops and cultivars, especially if fungicide seed treatments are not a management option for you. This concerns especially Kabuli-type chickpeas which are highly susceptible to Pythium seed and seedling rot. Delay seeding until soil temperatures have increase above 50oF.

Plant disease-free seed with maximum vigor to ensure rapid germination and emergence. This will reduce the window of susceptibility for infection, because older seedlings are less susceptible to Pythium (lignification of the root system provides a physical barrier to infection).

Department of Livestock - April 8th, 2022

Avain Influenza Reported in Poultry in Judith Basin and Cascade Counties

Helena, Mont. - On Friday, April 8th, the Montana Department of Livestock (MDOL) announced the confirmation of Highly Pathogenic Avian Influenza (HPAI) in two Montana flocks. These are the first cases of HPAI reported in domestic poultry in Montana since 2015. Montana is the 25th state to report cases of HPAI in domestic poultry in 2022.

Avian influenza is an infectious viral disease of birds that can cause high mortality rates in domestic flocks. Migratory waterfowl are the primary source for avian influenza (AI). Wild birds can be infected and appear healthy but shed virus in the feces, saliva, and respiratory secretions. Domestic poultry become infected through direct contact with infected wild birds, or through contact with contaminated objects, equipment, or the environment.

One of the flocks is a backyard flock in Judith Basin County and the other is a small layer and meat-bird operation in Cascade County. The flocks were reported to MDOL following increased rates of mortality and were confirmed to have the HPAI H5 strain associated with the outbreak occurring in other parts of the country. Samples from both flocks were tested at the Montana Veterinary Diagnostic Laboratory (MVDL) which is part of the National Animal Helath Laboratory Network, and confirmed at the National Veterinary Services Laboratory in Ames, IA. The capability of the MVDL allows state animal health officials to get a jump start on response while awaiting confirmatory results. Avian influenza is a reportable disease in Montana and the presence of avian influenza in a country or region can have significant impacts on the trade of poultry products.

The affected flocks have been plaed under quarantine and are required to be depopulated to prevent further spread of the disease. Flock owners are eligible to receive indemnity on their birds from the United States Department of Agriculture (USDA).

The Montana Department of Livestock is conducting an epidemiological investigation and will be identifying other poultry producers in the area to conduct disease surveillance and to provide educational resources.

As a result of this detection and the scope of the national outbreak, the Department is issuing an Official Order that prohibits all poultry shows, exhibitions, swaps, and public sales for the next 60 days to reduce the risk of exposure to HPAI. Exhibitions are an increased risk of HPAI because animals from multiple sources are concentrated in one area during the event. Cancellation of shows and exhibitions is a proactive step to prevent disease in our domestic poultry population. Depending on disease status in 60 days, this order may be modified or extended. The order does not apply to private, catalog, or retail sale of poultry.

In addition to cancelling shows and exhibitions, poultry producers should implement biosecurity measures including:

  • Prevent contact between wild or migratory birds and domestic poultry, including access by wild birds to feed and water sources.
  • House birds indoors to the extent possible to limit exposure to wild or migratory birds.
  • Limit visitor access to areas where birds are housed.
  • Use dedicated clothing and protective footwear when caring for domestic poultry.
  • Immediately isolated sick animals and contact your veterinarian or MDOL.

"Exposure to wild birds presents the greatest risk to domestic poultry," says Dr. Marty Zaluski, State Veterinarian. "Fortunately, reducing this risk can be accomplished with simple changes to biosecurity with minimal financial investment."

Sick birds can exhibit numerous signs such as swollen eyes, discolored comb and legs, significant drop in egg production or water and feed consumption, or sudden death. MDOL encourages all poultry producers to immediately report sudden onset of illness or high death loss in domestic poultry to their veterinarian or the department at (444-2976). If you find sick or dead wild birds that have died from unknown causes, please contact your local FWP Warden, Biologist or Regional office, or all the FWP wildlife veterinarian (577-7880).

MDOL emphasizes that existing safeguards to keep food safe and wholesome are sufficient to protect people, and the food supply in the United States is one of the safest in the world. Virus is rarely found in food and is readily destroyed by cooking.

"There is no increased risk to consumption of poultry or poultry products," Zaluski continued. "Normal food handling and preparation practices that keep food safe are important every day."

The Center for Disease Control (CDC) considers the risk to people from these HPAI infections in wild birds, backyard flocks and commercial poultry, to be low. No human infections with the virus has been detecetd at this time. However, it is recommended that people follow proper sanitary precautions when handling birds. Wear latex or rubber gloves when cleaning birds, washing hands with soapy water after cleaning, clean and disinfect equipment and surfaces that came in contact with the bird, and cook thoroughly before eating the meat. As a reminder, the US Department of Agriculture recommends cooking poultry to 165 degrees Fahrenheit.

The mission of the Montana Department of Livestock is to control and eradicate animal diseases, prevent the transmission of animal diseases to humans, and to protect the livestock industry from theft and predatory animals. For more information on the Montana Department of Livestock.

The grasshopper outlook for 2022 again looks troubling for much of Montana. USDA-ARS Northern Plains Agriculture Research Laboratory and MSU Richland County Extension will be hosting a Grasshopper Workshop, both on-site and online. to discuss grasshopper reserach and management on range and croplands nad the likelihood of large outbreaks in the region again this summer.

Two Private Applicator credits will be available to participants.

Tuesday, March 29th, 2022

10:00 AM to Noon

Richland County Extension Office Conference Room and live online

It is getting late in the calving season but we just had one report of a producer confusing nitrate (NO3) and nitrat-nitrogen (NO3-N) ppm levels on a forage report, potentially resulting in still born calves. The NO3-N ppm level needed to elicit health concerns in pregnant livestock is much lower than for NO3. For example, Levels of 350 - 1,130 NO3-N ppm should be limited to 50% of the total ration in bred livestock. When viewed as NO3, this range increases from 1,500 - 5,000 ppm. When working with and advising producers make certain they know nitrate levels can be reported as either NO3 or NO3-N and that feeding leves based on ppm differ between the two. Please reference the MontGuide "Nitrate Toxicity of Montana Forage" or contact Hayes Goosey [email protected]  or your local Extension Office with any questions.


Seasonal needle drop is the gradual yellowing or browning and eventual loss of older interior needles. Needles that drop due to age may have some spots and blemishes; however, they do not display typical symptoms of disease or insect damage.


Seasonal needle drop occurs in late summer to early fall. This casting of needles is triggered by weather and time of year, and many evergreens are likely to show symptoms at the same time.


The amount of needle loss is dependent upon species, temporal factors, and environmental conditions. White pines are seriously affected. Third - and even second-year needles yellow and fall throughout the entire tree. Austrian and Scotch pines typicallly lose only fourth-year needles. Cedars often display browning of leaves and flagging of older branchlets. Eventually entire branchlets are shed. Spruce and fir generally maintain many years of growth. Seasonal needle drop is typically not obvious but can be visible on inner branches. Larch and tamarack trees lose all of their needles every fall.


Management for seasonal needle drop is not necessary. If the yellowing and needle drop is restricted to older needles and is not extreme, it is likely not a problem. Maintain tree health. Irrigating evergreens thoroughly before the ground freezes will help to minimize the possibility of winter injury through desiccation.

By Oscar Perez-Hernandez and Jack Meyer

A sugar beet field with the majority of plants showing a dusty appearance on leaves was identified in south central Montana, near Billings, on September 9. Plants exhibited he symptoms both on the upper and underside of the leaves at moderate to high levels of severity. Close observation of the symptoms suggested they corresponded to the disease known as powdery mildew, which is caused by the fungus Erysiphe polygoni. Leaf samples were taken to an MSU lab for microscopic observation and confirmation of the pathogen identity. Scattered, whitish mycelial mats were observed on both leaf surfaces containing abundant, cylindrical to elliptical conidia (asexual spores of the fungus) that originated singly from straight, short conidiphores. No chasmothecia (sexual stage of the fungus) were present in the observed leaves. Occurrence of the disease in this field cioncides with a period of suitable weather conditions for this disease development in this location, namely: warm, dry weather, and large diurnal temperatures changes towards end of August-beginning of September. At this stage, since the crop in the scouted field is near harvest, a fungicide treatment is not justified. In situations where the disease is detected early in the season, a fungicide treatment would be recommended upon detection to reduce a potential rapid disease increase. Presence of th disease in this locatin constitutes a source of inoculum for healthy neighboring fields, though according to communication with the Yellowstone agriculture extension agent and area agronomists, no other field with similar symptoms have been observed as yet. Disease presence in this location suggests future imminent risk for seasonal incursions of pathogen spores into the area from afar overwintering sites.

For questions and further discussion please contact Dr. Oscar Perez-Hernandez, MSU Extension Row Crop Pathologist ( [email protected]  (406)994-4091

Scientific Name: Eratigena agrestis

During late summer and early fall it is normal for spiders to enter buildings and homes. This includes hobo spiders which have long been prevalent in Montana. Common misconceptions about the hobo spider often cause unnecessary concern.

Things to know:

  • Spider bites are rare. Generaly, their fangs are small and lack the musculature to pierce the human skin. They typically only bite if threatened or if trapped in clothing, shoes, etc.
  • There is no conclusive evidence that hobo spider vemon causes necrosis in humans; and a large body of scientific research that proves it does not.
  • The most common cause for necrotic lesions (wounds not healing) in the West is a bacterial infection called MRSA (Methicillin Resistant Staphylococcus aureus) infection. MRSA and other bacteria can enter the body through punctures which could include a spider bite, as well as many other more likely wounds. If a wound from any bite or scratch becomes inflamed, or if soreness persists, medical care should be sought as secondary infection that enters the body through the wound may need to be treated.
  • Hobo spiders are not known to be naturally aggressive in their native area or in the United States. Their nickname, the aggressive house spider, comes from an errant translation of their scientific name, Eratigena agrestis. The Latin translation of agrestis is not aggressive, but rather "rural" in "in the fields".

View PDF of Hobo Spiders Alert

On July 1st, 2021, Governor Greg Gianforte issued an executive order declaring a statewide drought emergency in Montana. The U.S. Drought Monitor indicates 98.7% of Montana faces drought conditions as of July 29th. Approximately 49% of the state is in either D4 (exceptional drought) or D3 (extreme drought), 31% in D2 (severe drought) and 19% in D1 (moderate drought). Conditions are expected to worsen over the next eight to ten weeks. Conditions are forcing agricultural operations to make difficult decisions due to high nitrates in forage, contaminated and limited water sources, lack of forage for livestock, insect infestations and many other related issues. This Ag Alert is a reminder of the many resources through MSU Extension that are available to assist individuals making difficult drough tdecisions across multiple disciplines.

Beef Cattle

This is a difficult year for beef cattle producers due to poor range conditions and lack of water. Numerous cattle have been sold in the recent months due to these conditions and the lack of hay available in their local area. Input costs will be greater this year due to rising hay prices and the need to purchase additional hay. Selling beef cattle and purchasing additional, more expensive hay will have implications for your future operations.

Forage and Nitrates

Nitrates are a concernt to livestock producers because of reduced animal performance, abortions, and even death. Forage nitrate is elevated in hot, dry conditions especially in annual hay crops (oats, barley, wheat) and, to a lesser extent, perennial grasses so producers should have any hay containing part of all grass or cereal tested for nitrate. In addition, drought often results in more nitrate-high weed growth in hay fields which are either directly grazed or are swathed, baled, and then fed to livestock. Using a lab to determine nitrate levels is the best approach, but there are a couple quick methods to know whether nitrate is likely to be an issue or not. For nitrate testing information see the MSU Extension MontGuide and consult your local MSU Extension office.

Finishing Reading full Drought Alert

BOZEMAN – Due to the extended drought in Montana, water availability in many areas has become severely limited. Reservoirs have dried up and are becoming covered in weeds. Montana State University Extension educators are cautioning livestock managers to evaluate weed feed and grazing land for nitrate toxicity during drought.

“Due to the severe drought, weeds have become prevalent across pastures and many producers are limited in their cattle movement this year,” said Custer County Extension Agent Mike Schuldt.

Although weeds can be high in protein and energy for livestock, caution should be used when cattle are grazing weedy areas or are fed weedy hay, according to Megan Van Emon, Extension Beef Cattle Specialist. Some weeds, including kochia, prostrate knotweed, Rocky Mountain Goosefoot and Lambs Quarter, accumulate nitrate during draught conditions. These weeds may be the only green feed available, and livestock often gravitate to green areas to graze.

Recently, Schuldt and Van Emon investigated a weedy reservoir and collected samples for nitrates. When analyzed through a Nitrate Strip Test, the Rocky Mountain Goosefoot had approximately 50,000 ppm of nitrate and the Lambs Quarter and knotweed had approximately 10,000 ppm of nitrate. Van Emon said these levels are extremely high and should not be fed to livestock. Nitrate Strip Tests are available at MSU Extension county offices.

“These weeds were extremely worrisome due to their ability to accumulate nitrates, and this became more apparent after we watched a cow grazing in the area and eating the Rocky Mountain Goosefoot,” Van Emon said. “The producer indicated that these weeds are normally not present and when traveling through the pasture, the Goosefoot and Lambs Quarter were not observed anywhere other than the dried reservoir.”

Ideally, feed or grazing pasture for livestock should contain less than 1,500 ppm of nitrate, said Van Emon. As the concentration of nitrate increases, more risk is associated with providing those feeds to livestock. Van Emon recommends keeping livestock away from feed that has nitrate concentrations over 10,000 ppm.

“The recommendation to the producer was to remove the cattle from the area of concern or fence off the reservoir to reduce the risk of cattle grazing the weeds,” Schuldt said. “Nitrate concentrations at that level are concerning and nitrate toxicity symptoms and death can occur rapidly."

Symptoms of nitrate toxicity in livestock include labored breathing, muscle tremors, weakness and staggering gait. If these symptoms are observed, remove the nitrate-containing feed or move the livestock out of the pasture and contact a veterinarian for a treatment plan right away. When moving cattle from a high-nitrate feed area, move them slowly, as moving livestock too quickly can exacerbate the symptoms.

July 2021 - Laurie Kerzicnik ([email protected])

Blister beetles have been aggregating and causing defoliation on trees and shrubs in yards and gardens. Some of the more common species present are those in the genus Epicauta.

Blister beetles in the genus Epicauta lay eggs in areas surrounding grasshopper eggs. The immature stage (larvae) will feed on these grasshopper eggs.


The adults chew leaves and foliage. They also can leave some fecal spots. They will feed togther in large groups and can defoliate plants. They are called "blister beetles" because they have a defensive oil called cantharidin that can cause blistering. The blister beetle species in gardens have very low amounts of the cantharidin.


Blister beetle infestation are temporary and generally only last for a few days. The damage rarely causes economic hardship to established or older trees. Management is often not necessary in these situations.

If chemical control becomes necassary, some active ingredients for adult blister beetle control for woody ornamentals include pyrethrins, carbaryl (products such as Sevin, Bonide Fruit Tree Spray, Bayer Complete Insect Killer for Gardens), and pyrethroids (active ingredients zeta-cypermethrin, gamma-cyhalothrin and lambda-cyhalothrin-some example products include Safer Yard & Garden Insect Killer II Ready-to-Use, Ortho Tree and Shrub Fruit Tree Spray, Ortho Home Defense Max Insect Killer for Lawns & Gardens Ready-to-Spray).

Please note: These recommendations are not intended for crops or rangeland.

View Fact Sheet (PDF)

Disclaimer: These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. The authors and Montana State University assum no liability resulting from the use of these recommendations. The Montana State University Extension Service is an ADA/EO/AA/Veteran's Preference Employer and Provider of Educational Outreach.

June 16th, 2021

We are receiving many reports of MSU winter wheat variety "Bobcat" showing foliar leaf spots across the state. The leaf spots are tan to brown in color with yellow halos around them and resemble those associated with tan spot disease or chloride deficiency. Lesion from chloride deficiency tend to have more discrete margins between affected and nonaffected tissue while the margins of fungal lesions tend to be more diffuse. We have observed leaf spot symptoms in Bobcat in previous years, as well, but this year's drought conditions and temperatures extremes have likely exacerbated this phenotype.

At the Schutter Diagnostic Lab we have assessed several "Bobcat" samples for the presence of the tan spot pathogen (Pyrenophora tritici-repentis) or other pathogenic causes. At this point, we have no convincing evidence that the observed spotting is caused by a fungal pathogen. The leaf spots are more likely of physiological nature (physiological leaf spot, PLS), which is often caused by chloride deficiency. If disease is ruled out, then chloride deficiency is suspect. In most winter wheat fields this year, it's likely too late to have a large benefit with a chloride treatment, but if you decide to try, 10 - 20 lb potash per acre should be sufficient or a similar amount of chloride applied as a liquid (for example calcium chloride or ammonium chloride).

If you observe leaf spot symptoms we encourage you to drop a sample (whole plant) at your local Extension office or submit directly to the Schutter Diagnostic Lab and await diagnosis before applying fungicides (sample submission instructions and forms can be found on the Diagnostic Lab website). If you want to rle out or rule in chloride deficiency, the suggested critical level in plant material (entire plant) is between 0.1 and 0.4% with large yield increases and leaf spot decreases when chloride was applied at tissue Cl concetrations below 0.1%. Please note that the Schutter Diagnostic Lab does offer tissue analysis or soil testing services.

Click here for more information

Abiotic (Non-Infectious) Symptoms in Wheat

By Andrew Friskop, NDSU Extension Cereal Crops Pathologist, and Joe Ikley, NDSU Weed Extension Specialist

Source: NDSU "Crop & Pest Report" June 10, 2021

The extreme differences in temperature, low relative humidity, and water stress has led to unusual leaf spots on wheat. This year several reports of wheat with bizarre and unusual leaf lesions have been received and can be misdiagnosed as a disease. This report will review some of the key diagnostic features of abiotic (non-infectious) disorders.

Color Banding

The extreme differences in nighttime and daytime temperatures has led to several reports of color banding in wheat. Symptoms of color banding include yellowing and/or purpling of leaves that have recently emerged. These first leaves are sensitive to soil temperature and injury can commonly occur. We usually observe this abiotic disorder early in the growing season during frost events. This year we have observed color banding on late emerging wheat that has been exposed to temperature extremes. Heat canker (leaf tissue death) is another abiotic disorder that is commonly observed on wheat emerging during hot days. Regardless, wheat whill recover from this injury and it should not impact crop development.

Brown Irregular Spots

Brown to chocolate colored lesions have been reported from several fields. The brown spots have been observed on the natural fold of the leaf or confined to certain leaves. These lesions can be confused with fungal leaf spots due to the color and appearance on a leaf. Fungal leaf spot lesions (ie: tan spot Septoria) will often have a definitive margain, have an ellipsoid shape, will not be confined to a certain leaf, and will be found in fields near wheat residue experiencing several days of prolonged leaf wetness. The brown abiotic lesions are likely a physiological response to the environment and will not affect crop development.

Bleached Spots

Crop injury from a chemical application has also been observed this year. Chemical injury can occur if pesticides are applied during hot days or can result from an off-target application. Lesions caused by chemicals may be irregular, necrotic, have a bleached center or may have a distinct "halo" surrounding the lesion. Necrotic lesions can sometimes be caused by oil adjuvants or oil-based herbicide formulations, but the injury is usually associated with a contact herbicide. Lesions with a distinct halo and bleached center are typical of paraquat and group 14 herbicides. Chemical injury will often follow a field spray pattern (ie: field wide or boom width) and be found on plant tissue available at the time of application. Finally, chemical injury will suddenly appear after an application has been made.

The original article as part of the June 10th, 2021 NDSU "Crop and Pest Report"

June 3rd, 2021

In Montana, it is not uncommon to have late spring cold snaps after things have started to produce new growth in the early spring. This can damage newly emerged leaves, shoots, and flowers especially when temperatures dip to the mid-high 20s. This damage is usually noticeable a few days to a week after the freezing temperatures as wilting and browning of leaves and needles, in addition to potential defoliation of severely damaged growth.

With the cold snap that occured in the last couple of weeks of May, along with the snow that accompanied it, Montanas are now seeing some of the resulting damage to their trees, shrubs, and early season annuals.

Although the damage can look significant and alarming, most of the discoloration that we are seeing in the state is largely aesthetic, and new growth has already started to resume. Although some of these plants may have stunted growth in the early part of the growing season, most will recover when appropriately cared for, since late winter cold snaps rarely have lasting impacts on healthy trees and shrubs.

To learn more about environmental damage to trees and shrubs, visit the following links:

June 10th, 2021 - Laure Kerzicnik

  • Grasshoppers are becoming an issue around the state.
  • Once grasshoppers are adults and have entered the yard and garden, management is extremely challenging.
  • Consider focusing on the most vulnerable trees and plants for management (and those of importance)
  • Management options are available but several applications might be necessary (following the label).

Life Cycle

  • Most grasshoppers overwinter in the egg stage in the soil. After egg hatch in mid-to late spring, the nymphs (immatures) immediately begin feeding
  • There are at least five or six stages of nymphs before the grasshoppers reach adulthood
  • The adult grasshoppers can live for several months into late summer/early fall


  • Many plants and flowers will be hard to protect
  • Screen the garden and sensitive areas with metal window-type screening, as they easily chew through fabric
  • Be prepared early next year for possible grasshopper issues

Several insecticides are available and labeled for use on grasshoppers

Organic Insecticides & Biological Controls

  • Neem oil (products such as AzaGuard)
  • Pyrethrins (products such as PyGanic)
  • Nosema Iocustae (brands such as NoLo Bait)
    • Nosema locustae is a protozoan/fungus that is selective to grasshoppers and applied with a bran that the grasshppers have to consume. Only effective when grasshoppers are in their 1st and 2nd nymph stages (when the grasshoppers are 1/4-1/2" long)

Non-Organic Insecticides

  • Bifenthrin & zeta-cypermethrin (products such as Ortho Home Defense Insect Killer for Lawn and Landscape and Ortho Bug B Gon Insect Killer for Lawns and Gardens)
  • Cyfluthrin (products such as Bioadvanced Complete Insect Killer)
  • Carbaryl (Eco Bran bait or Sevin)

Grasshopper Control in Gardens and Small Acreages

May 27th, 2021


Freezing temperatures during the spring may cause leaf tips to turn yellow and necrotic. During stem elongation, cold temperatures may damage the stem and cause it to split or cause damage to the vascular system (water and nutrient transport), which will cause the stem to collapse and lodge. The damage area on the stem may be bleached and water-soaked. The growing  point or spike may be damaged with few symptoms on the stem. The emergence of chlorotic leaves from the whorl may indicate that the developing spike has been killed. More leaves will become chlorotic as the culm deteriorates. Primary symptoms of freeze injury to wheat at spring growth stages and its effect on yield are listed on table 1. Further information on freeze injury symptoms in wheat can be found in the publication from Kansas State University "Spring Freeze Injury to Kansas Wheat"


Freeze injury during stem elongation can damage heads and result in shriveled, deformed, and pale heads. More information on freeze injury symptoms in barley (and oats) can be found in the "Frost Identification guide for cereals" published by the Government of Western Australia Department of Promary Industries and Regional Development and the Grains Research and Development Corporation and can be found here.


The most recognizable symptom of freeze injury on pea leaves is th death of interveinal tissue, which appears water-soaked at first and then turns necrotic brown. Young leaves may be affected entirely and have a scorched appearance. Chickpeas are generally more sensitive to freeze injury than lentils. From a distance, the top leaves of injured plants turn yellow to white and appear dry. Sometimes only the leaf margins dry up and appear scorched without developing lesions of definite shape or size. More information on freeze injury symptoms in pulse crops (canola, and lupine) can be found in the "Frose Identification Guide for Canola and Pulses" published by the Government of Western Australia Department of Primary Industries and Regional Development and the Grains Research and Development Corporation.

May 2021

We have several social wasps in Montana. Except for the Western yellowjacket, social wasps are typically not aggressive unless their nest is disturbed. Most are beneficial and feed on a lot of our garden pests. Our most common wasps are bald-faced hornets, aerial yellowjackets, Western yellowjackets, and paper wasps.

They live in colonies, which include workers, queens, and males. They all feed on insects. The Western yellowjacket is a scavenger, feeding on garbage, sugary materials, and dead insects. It is the biggest nuisance pest around our backyards and porches in late summer. Although other wasps and bees can sting, most of our stings come from the Western yellowjacket. Social wasps make paper-like nests annually in the spring from wood materials. Wasp nests are abandoned in late summer, and only the fertilized females will overwinter; all the workers and males die.

Locating wasp nest in the spring can be challenging. Western yellowjackets nests are often subterranean or can sometimes be in wall voids. Wasps can fly up to 1000 yards, so sometimes the nest can be quite a distance away.


Traps are available for Western yellowjackets (available at hardware and garden stores). They don't trap other common Montana wasps or bees. These traps are most effective when placed out in the spring when the queens emerge and before the Western yellowjacket colonies become large.

Controlling some of the larger nests can be difficult later in the summer. There can be hundreds to thousands of wasps in the colony, and the nest can be the size of a basketball or larger. After a couple of serious frosts and cold weather, the wasps will be dead and you can knock down the paper nests. The abandoned nests are not used again the following spring and will rapidly decompose during the winter.

Soapy water can be applied to the nests at night and can be effective where nests are exposed and accessible. Exposed and accessible nests may also be enclosed at night with large garbage bags and frozen. Weat protective clothing, such as a bee suit and proper eye protection.

Remove and limit exposure to any attractie food sources around the outside of the home, including garbage can, pet food, droppings from the grill, and any food or sugar source. Make sure garbage cans are sealed well. Similarly, make sure that dumpsters are sealed to the best extent possible in recreational areas.

Venom and Stings or Social Wasps

Social wasps use their sting and venom for defense and can sting multiple times. Some of the larger species can inject greater quantities of venom. People vary in their responses to the venom with most people suffering only pain and swelling. A few, however, may suffer severe allergic reactions.

Chemical Control

Active nests can be controlled chemically with a series of wasps sprays. Such active ingredients include permethrin, deltamethrin, tralomenthrin, bifenthrin, tetramethrin, and allenthrin. If using any of these products, apply them late in the evening, early morning, or on cool, rainy days when the nest is not very active and more members of the nest are present. If controlling a Western yellowjacket nest, this might require several applications. Never plug what you think might be a Western yellowjacket hole on the outside of the house; this might force them to more further into the house and not have a way to exit.

View article and pictures here

Published May 4th, 2021


Apple, Pear, Crabapple Tree


Caterpillars tunnel inside the fruit and deposit excrement. Holes and egg-laying spots are also evident on the outside of the fruit.

Life Cycle:

Codling moths overwinter as pupae in tree bark cracks and soil near trees. As temperature warm in the spring (approximately above 50oF), adults emerge, mate, and begine laying eggs near fruit sites on trees. After eggs hatch, larvae feed on leaves, shoots, and later burrow into fruit until they ppate to emergy again as adults. Depending on temperature, there can be up to three generations in Montana per growing season.


Pick up and dispose of dropped fruit. In small plantings, individual fruits can be protected by pruning each cluster when the apples are about the size of a quarter. This can reduce larval burrowing between touching fruit. Remove small or weakly attached fruits until there are about 1 - 2 apples. Then the fruit can be wrapped in nylon footlets. Staple the footlet at the top.

Trees can also be wrapped in corrugated cardboard, which can help trap larvae that are leaving the apples to find a place to pupate. The cardboard should be removed and destroyed before adults emerge.

Mating disruption is a management technique that involves releasing a male sex attractant into the air to attract males and to disrupt mating. This works optimally with areas of 1- acres or greater.

The timing of chemical controls is critical and coincides with egg laying, which is after flowering and dependent on the number of accumulated degree days. Never apply a chemical spray during bloom.

The initial emergence of moths is referred to as biofix and involves the capture of male moths is pheromone traps. The timing of chemical controls is based on the degree days accumulated from biofix to target the greatest period of egg hatch. Degree days and percentage of egg hatch are calculated by using the equation and table on this website.

Degree days = ((maximum daily temperature + minimum daily temperature)/2)) - 50oF (base temperature of codling moth development)

Several chemical controls are available. Some of the organic options include the active ingredients spinosad, Bacillus thuringiensis var kurstaki (or Btk) (please note: Btk requires repeated applications with complete coverage), Kaolin clay, horticultural oil, and the codling moth granulovirus (CpGV or Cyd-X). Conventional controls include the active ingredients carbaryl, malathion and permethrin.

Subsequent sprays should be applied according to the label of the chemical chosen, You can use a nearby weather station to calculate degree days and estimate emergence of larvae using the Online Phenology and Degree Day Model provided by The Western Agricultural Research Center (WARC) has resources specific to home growers which emphasize non-chemical controls and a page specific for commercial growers.

View pictures of the moth here

Published April 16th, 2021

With the warm and dry winter temperatures we have had over the past few months, the Schutter Diagnostic Lab has been receiving several samples of evergreen trees and shrubs with symptoms of winter injury.

This is a cultural/environmental issue:

Resulting from minimal snow cover and extended periods of low humidity, narrow, and broad-leaved evergreens (especially spruce, Douglas-fir and pines) are subject to drying out, especially if supplemental irrigation is not applied to the plants during the fall and winter months. This results from the plants continuing to lose moisture through transpiration at a rate faster than it can be replenished. Common symptoms include red, yellow or brown discoloration of foliage, especially on needle tips, and can sometimes affect entire branches. Damage is more pronounced on the south and south-west sides, and can also cause damage to roots which can further impact their ability to replace lost moisture.

Damage can be more severe in areas with high wind exposure, during periods of large fluctuation between daytime and nighttime temperatures, and on younger/newly transplanted trees and shrubs without well-established root systems.

These symptoms, although they appear alarming, will be less obvious as soon as the tree pushed the new growth and/or drops its dead needles. As long as the buds are soft and green (as they are in this case), there is still good growth and life in the tree. It is important to make sure your trees are watered thoroughly and regularly during dry periods, especially into the fall.

Please open the following links for information about caring for stressed trees:

Helping Trees to Manage Stress

Simple Steps to Aid Stressed Trees

Read original urban alert here(PDF)

Published April, 2021

This table presents information on available fungicide products for management of widespread seedborne and soilborne diseases of pulse crops (peas, lentils, and chickpeas) for use in the United States. The information is based on labelled application rates according to label instructions and the presence of disease. The table includes the most widely marketed products and is not intended to be a list of all labelled products nor is it an endorsement of any specific product. Consulting this table does not substitute careful reading of the product label before an application is made.

View Pulse Crops Treatment and Disease Control Table here

**Another browm marmorated stink bug was confirmed from inside the car of a homeowner in Kalispell on May 5th, 2021.

The invasive brown marmorated stink bug, Halyamorpha halys, was confirmed for the first time in Montana on January 26th, 2021 (from inside a home in Billings).

The brown marmorated stink bug was introduced from Asia and is now established in 46 states (Montana is the 47th state but not sure if it is yet established) and 4 Canadian provinces. It attacks over 170 different plant species. This is a pest that was expected to arrive in Montana. Its potential impact on crops, specialty crops, backyard gardens, and as a fall home invader in Montana are unknown.

Its detection in other states poses problems ranging from a nuisance to a severe agricultural pest.


  • Brown marmorated stink bugs have stylet's, which pierce into the fruit, pods, buds, leaves, and stems of several plants.

Preferred Hosts:

  • Yard and Garden
    • Some preferred hosts in the yard and garden include catalpa, sunflower, crab apple, apple, cherry, and other Prunus species.
  • Crops
    • Corn is a favored host
  • Specialty Crops
    • Apples, pears (Asian and European), grapes, peaches, sweet corn, pepoers, Swiss chard, and tomatoes.

What We Know about Brown Marmorated Stink Bugs

  • Wide host range
  • Damaging pestof apples, grapes, cherries, and several other Prunus species
  • It is a serious pest of ecnomic importance for tree fruits in the mid-Atlantic states and has caused more than $37 million worth of damage (report as of 2010).
  • Itis detection in other states poses problems ranging from a nuisance to a severe agricultural pest.
  • Invades homes in the fall (nuisance pest)
  • Harmless to humans

What We Don't Know About BMSM in Montana

  • If it is established in Montana (if reproductive populations exist in Billings and other areas of te state)
  • What hosts might it impact and whether it will be a pest of ecomonic importance for crops and specialty crops.

Monitoring and Management:

  • Several cooperating state and federal agencies have been monitoring for BMSB for several years in Montana.
  • Monitoring efforts will continue with a focus in the Billings area.
  • Please send suspected specimens and/or detailed photos to your local extension agent or samples can be submitted to the Schutter Diagnostic Lab by following directions at
    • There are several look-alike bugs

April 6th, 2021

The common ticks in Montana this time of year are the Rocky Mountain wood tick, Dermacentor andersoni and the American dog tick, Dermacentor variabilis. Ticks can be transported into the home from pets and humans. The two species look very similar. The two species of black-legged ticks (also known as deer ticks, Ixodes scapularis and I. pacificus) that vector Lyme disease have not become established in Montana although they are occasionally brought into the state by travelers (both humans and pets).

The Rocky Mountain wood tick is found on livestock, companion animals, and humans in the spring and summer in Montana. It likes stream corridors, grassy meadows, and south-facing sagebrush slopes. It can transmit viral Colorado tick fever (CTF), Rocky Mountain spotted fever (RMSF), bovine anaplasmosis, and tularemia. The American dog tick is found in eastern Montana. It is one of the main vectors of RMSF and can also transmit tularemia. Neither the Rocky Mountain wood tick nor the American dog tick transmit Lyme disease.

Rocky Mountain spotted fever transmission is rare in Montana; most cases occur in the southern Atlantic Region. The tick must remain attached for at least 10 hours before transmission of RMSF can occur. In many cases, a blotchy red rash will appear on the extremeties, often starting with the wrists, palms, and soles of feet.

Colorado tick fever occurs only in western states. In Montana, cases have been diagnosed west of the Continental Divide-southwest and south-central Montana. Symptoms of CTF occur within four days and include chills, headache, fever, muscular aches, and general malaise.

There have been no Montana-acquired cases of Lyme disease at the time this was written, and it is unlikely this will change in the foreseeable future. Questions about Lyme or other tick-borne diseases should be referred to competent physician.


Use a repellent like DEET or picaridin expecially on pants and socks when in ticky areas and check for ticks after being outdoors. If in a brush-type area or an area with tall grasses, always do your tick checks right afterwards.

Removing a tick from your skin

You want to find and remove ticks as soon as possible. There are some common folklore tick removal methods such as "backing out of the tick with a burning match" that should not be attempted. This method is not safe and doesn't work. It is important to try to thoroughly remove the tick and the mouthparts. The tick has mouthparts which are barbed and use for insertion into the skin. If these break off, it can be a further source of irritation and possible infection. Also, the crushing of the mouthparts can allow for disease transmission to occur through the skin if not removed properly.

Place forceps (try to use blunt curved forceps or tweezers) around the tick mouthparts as close to the skin as possible. Remove the tick with a slow, steady pull away from the skin. Don't jerk or twist the tick. Avoid getting or crushing any tick parts on you. Disinfect your skin with alcohol and wash your hands with soap and water.

In Montana, we cannot test the tick itself for diseases. For further information on testing ticks for diseases and wehre you can send them, visit You must keep the tick alive to test for diseases.

If you have futher questions about the ticks and diseases, see the following resources:

Ticks of Veterinary and Public Health Importance In Montana

Tick-borne Illnesses

Centers for Disease Control and Prevention - Ticks

Click here to view Urban Alert PDF

Be Aware: Colorado Tick Fever

A large number of Colorado tick fever (CTF) cases were reported in Montana last summer. CTF virus is spread by the Rocky Mountain wood tick which is commonly found at elevations between 4,000 and 10,000 feet in the western United States and Canada. Ticks are active in spring and summer. The best way to protect yourself from CTF is to prevent tick bites.

  • Wear insect repellent when working outside
  • Stay on trails whenever possible
  • Check your clothing and gear for ticks that can hitch a ride home and then attach to you or others later.
  • Perform tick checks soon after returning indoors. Showering and running your clothes through the dryer on high heat for 10 minutes can help get rid of unattached ticks.


Revised 1/18

Mosquitoes are serious nuisance pests due to thier persistent biting behavior and are responsible for affecting the health and well-being of humans, companion animals, livestock, and wildlife. This MontGuide describes the biology and life cycle of mosquitoes, their impact in the state, and provides information on repellents and their proper use for personal protection.

Mosuitoes are a group of flies that occur in almsot every region of every continent in the world except Antartica. There are 3,200 recognized species worldwide with approximately 51 species found in Montana. Mosquitoes are the most important anthropod affecting human health due to annoyance, discomfort from bites and transmission of diseases. They are second to ticks in affecting the health and well-being of livestock and companion animals. Lewis and Clark and the Corps of Discovery encountered enormous numbers of mosquitoes while traveling along the Missouri River in 1805. The expedition noted the mosquitoes were so intense they had to move their campsite to escape the relentless blood-sucking attacks. Their only other defenses were smoky fires and a repellent made from tallow and hog's lard.

Description and Life Cycle

Mosquitoes can be classified as either floodwater or standing-water species. Floodwater mosquitoes deposit individual eggs during the summer on damp soil in low-lying areas. These eggs will hatch the follwoing summer if the area is sufficiently flooded with runoff from snowmelt, rainfall, or irrigation water. Because hatching and immature development are synchronized by flooding events, adults tend to emerge at the same time. The number of generations of floodwater mosquitoes produced in one summer depends on the number of times an area is flooded.

Standing-water mosquitoes overwinter as adults in animals burrows, inside buildings, and under bridges, in culverts, etc. In late spring they come out of hibernation and begin deposting eggs on the surface of permanent or temporary pools of water.

Impact of Mosquitoes

Mosquitoes do have an ecological value in serving as food for other organisms. However, this benefit tends to be overshadowed by the intense irritation they cause for livestock, wildlife, and humans. Cattle attacked by mosquitoes often bunch together or constantly move to get relief from the intense biting. Distruption of normal grazing and resting behavior by mosquito swarms often results in reduced productivity in terms of decreased weigh gains and milk production. For people, outdoor activities in the summer are often disrupted or even canceled because of the annoyance from swarming, biting mosquitoes.

Although mosquitoes can be a severe nuisance, the real danger they pose is disease transmission. In Montana, there are several encephalitic viruses and one nematode they can transmit.

West Nile Virus (WNV)

The first report of WNV in the U.S. was in New York City in 1999. It is unknown how the virus was intoduced to the U.S., although it may have been from shipments of exotic birds or infected mosquitoes transported in ships or planes from overseas.

Horses are very susceptible to WNV. In the fall of 2002 and summer of 2003, prior to the development of a WNV vaccine for equines, several hundred horses were infected with WNV in Montana; approximately 40 percent of these cases were fatal.

Canine Heartworm

Canine heartworm is a nematode that lives in blood vessels of the heart and lungs of dogs and other canines, including foxes and coyotes. Cats can also become infected.

The risk of transmission for canine heartworm is low in Montana due to the cool, short summers, which prevent the microfilaria from developing to the infective stage in the mosquito.

Personal Protection

There are many products available that provide protection from mosquitoes. The Center for Disease Control (CDC) recommends four over-the-counter products containing active ingredients registered by the Environmental Protection Agency (EPA) for use on skin and clothing.

Click here to read the full MontGuide on Mosquitoes

Reviewed 3/17

Biting midges are considered serious pests in Montana because they are vectors of two diseases that affect livestock and wildlife: bluetongue disease and epizootic hemorrhagic disease. This MontGuide describes the biology and life cycle of biting midges in the genus Cullcoides, their impact in the state, and recommendations for their control.

Biting midges are flies that belong in the family Ceratopogonidae. Within this family, midges in the genus Culicoides are very small and are often called "no-see-ums". They are tiny enough to fly through window screens, and their aggressive, persistent biting behavior has led to the development of specialized tent screens with a very fine mesh netting to prevent them from entering. In our biting midge studies in Montana, we have collected 12 species of Culicoides. Of these, some feed preferentially on large animals and others on birds. We seldom receive reports of midges attacking humans. The primary species of importance in Montana is Culicoides sonorensis, which readily feed on livestock and wildlife and is the principal vector of the viruses causing bluetongue disease and epizootic hemorrhagic disease.

Description and Life Cycle

Adult Culicoides midges are usually 1 to 2.5 mm long, with distinctive wing patterns that are important for species determination. They are more adundant near productive breeding sites, but will travel an average of 1.5 miles in search of a suitable host.

Once a host is found, female midges feed by lacerating the skin and siphoning the blood up as it accumulates in the wound, a process called pool feeding.

Finishing reading the full discription and life cycle here

Impact of Biting Midges

In Montana, biting midges are seldom a public health concern.

Because of their small size, biting midges are difficult to see, and their bites are often mistaken for mosquito bites. In North America, biting midges are not responsible for human disease transmission; however, they are considered important vectors of various human disease in other parts of the world.

Two livestock/wildlife diseases transmitted by C. sonorensis in Montana are bluetongue disease and epizootic hemorrhagic disease. Bluetongue and EHD are very similar in many respects; the viruses are closely related and their clinical symptoms are difficult to tell apart. Neither disease is spread through contact; transmission between animals can only occur through the vector, C. sonorensis.

Control of Biting Midges

There are some management practices livestock producers can implement to control C. sonorensis or reduce blood feeding. However, controlling biting midges is difficult because of the diversity and abundance of habitats where they are produced. Some potential management tactic include increasing the slope of stock ponds, thereby making the edges unsuitable for egg-laying by female midges. Repairing and fixing overflowing stock tanks can elimate sites where midges develop. If possible, livestock can be housed between dusk and dawn to provide some protection from host seeking midges.

To read full MontGuide on Biting Midges, click here!

Revised 04/18

Bed bugs are blood-feeding pests that are invading human living quarters in increasing numbers.

Bed bugs occur regularly in Montana, though at low numbers relative to many other locations in the U.S. As is true elsewhere, infestations of these nocturnal blood-feeders appear primarily in rooms where people sleep, particularly in bedding. Places where there is abundant human traffic arriving from diverse locations (such as apartment complexes, health care facilities, and tourist accommodations) have increased odds of infestation and must be monitored carefully.

Risk Factors

While sanitation helps, even the cleanest indoor environment may harbor bed bugs. An accommodation that has frequent turnover of residents and high-density stays is at higher risk for bed bug infestations. Although smaller cities are not exempt, larger cities tend to have higher instances due to increased cases fitting the above criteria.

Identification, Life Cycle, and Effects on Humans

Bed bugs are reddish-brown, oval, flattened, wingless, blood-feeding insects that are just under one-quarter inch long.

Females may live for a year, depositing up to 400 eggs in their lifetimes.

Severe infestations can cause anemia in children and the elderly and lead to sleeplessness and stress in the home.

After feeding, bed bugs move away and lie inactive for several days before deposting a cluster of white eggs. Females seek another opportunity to feed after deposition of eggs, a cycle repeated throughout their lifetime.

Look-alike Species

Similar-looking species of "bat bugs" and "bird bugs" in the same insect family (Cimicidae) can also bite humans.

Magnification is required to distinguish these look-alikes from bed bugs. When viewed on its back, the left side of an adult female bed bug has a narrow, pointed notch onthe fourth visible abdominal segment.

Difference in the shape and thickness of the hairs fringing the body segments can also help seperate bed bugs from both bat bugs and swallow bugs. Bed bugs of both sexes have short body hairs that curve backward slightly, while she look-alikes have long, slender hairs that stand straight out.

Bed Bug Control

Getting rid of bed bugs requires a multi-faceted approach that includes prevention, removal of access points and hiding places, and thorough cleaning. With these measures in place, pesticides are not always warranted.

However, if pesticides are to be used, then careful selection of properly labeled products is a must.

Homeowners should NEVER apply pesticides which are not specifically labeled for bed bugs in the home.

The illegal use of some organophosphate, pyrethroid or carbamate pesticides may cause allergies, asthma, immune systems hypersensitivity, nausea, convulsions, or death.


Be wary of bringing infested items into your home. Bed bugs are now quite common in many areas of United States in some foreign countries, and they do infest luggage. Inspect all clothing and baggage for fecal spots prior to unpacking. At home, seal all crevices that may provide shelter for bed bugs. Caulk will work around windows and baseboards. Tighten up any loose electrical outlets, and repair loose or torn wall paper. Outlet cover plates with hinged or sliding socket covers are now available.


Sanitation includes daily vacumming of all potentially infested rooms. Mattresses can be vacuumed with a brush attachment to help scrape eggs off the fabric.

Sheets, blankets, and clothing should be laundered in hot water and can also be placed in a hot dryer for 20 minutes to kill bed bugs.

Removing Access Points and Hiding Places

Bed bugs cannot fly so they must access beds by crawling. They often access beds directly from walls, curtains or from overhanging bedspreads which contact the floor. Beds should be carefully examined to remove these access points. Double-sided tape can also be wrapped around the legs of the bed to limit access.


Bed bugs should be managed using an integrated management approach. Bed bugs are difficult to manage using only pesticides. Homeowners are urged to contact commercial pesticide applicators rather than attempting to manage bed bugs using pesticides on their own.

To read the full MontGuide on Bed Bugs, click here!

Blister beetles are leaf-feeding insects that secrete a liquid that can cause blisters, and can be toxic when accidentally fed to livestock in forage. Of nine species observed in Montana, only one has been reported to have damaged crops.

Read Full Article

Adult Alfalfa weevils are snout beetles approximately 3/16 inch long. They are light brown with a dark brown stripe from the head to about three-quarters down the back, narrowing as it progresses down the back. Older weevils may have a less distinct stripe. In colder regions where adults do not become active until spring, over wintering is thought to occur outside alfalfa fields. In warmer regions where adults are active during the winter months, overwintering is thought to occur within alfalfa fields. When temperatures warm to about 48 degrees F in the spring, the weevils become active.

Click here to read more on alfalfa weevils!

Montana and the surrounding region are currently observing large numbers of "miller" moths congregating near buildings at night where they are attracted to sources of light. Any type of moth that is abundant around homes have been called Miller Moths. In Montana and surrounding states it is typically the adult stage of the army cutworm. Euxoa auxiliaris.

The larval caterpiller stage feeds on a variety of plants and crops during the spring season, and now in early summer the emerging adult stage migrates from the plains to higher elevations in mountains.

Later in August and September the moths return to the plains to mate and lay eggs.

Want to read the full MontGuide? Click here!

Watch for false chinch bugs in mustards and canola, as they are reportedly causing damage to mustards in several Montana locations. They feed on plant sap with strawlike mouthparts.

In high numbers false cinch bugs can cause significant wilt and dieback.

Physical apperance and life cycle

Management Approches in Wheat

Problems in Urban Landscaping

There are several viruses of wheat and barley in Montana that can be economically important. Here we describe the symptoms and control for these diseases.



June 8th, 2020

Wireworms are reported in high numbers in small grains across much of Montana. Wireworms are the soil-dwelling larvae of click beetles.

Wireworms cause damage to the seeds, roots, tubers, and bulbs of various crops.

They are worm-like larve up to one inch in length, with a hardened exoskeleton and variable color depending on species, from whitish to orange.

Wet Soil Conditions Favorable for Wireworms

Grasshoppers in Yards and Gardens

Grasshopper outbreaks are occurring in several areas in Montana. They are difficult to control due to thier migratory nature and voracious feeding on several host plants. They tend to avoid feeding on trees and large shrubs unles outbreaks are heavy.

Most grassshoppers overwinter in the egg state in the soil. After egg hatch in mid to late spring, the nymphs immediately begin feeding. There are at least 5 or 6 stages of nymphs before the grasshoppers reach adulthood. The adult grasshopper can live several months into late summer/early fall.


Pear Slugs

Pear slugs chew the leave of many common trees and shrubs such as Cotoneaster, Cherry, and other related plants.

Pear slugs are not true slugs. They are a type of insect known as sawflies.

Two generations of pear slug occur. Most damage usually occurs from the second (September) generation.

When severe defoliation is threatened, pear slug injury should be controlled.

More on Pear Slugs

Blister Mites on Apple Trees

They prefer to host on Apple, Crab Apple, and Pear trees.

The mites overwinter as adults beneath bud scales. When the buds start to grow in the spring, mites attack the emerging leaves. Their activity increases in teh summer with two-three generations per year.

More info

Alfalfa blotch leafminer is a European pest that was accidentally introduced to the northeastern U.S. in the late 1960's. Since then, it has spread westward across the northern U.S. and through the maritime and prairie provinces of Canada.

This insect has been present in Wisconsin and Minnesota since the mid-1980's.

Read the full article

Honeylocusts have been looking thing, showing brown tips, and defoliating. This is likely due to the honeylocust pdogall midge. These are common every year, but damage from the pest is more evident this year.

More info on Damage, Scouting, and Management, click here!

Montana has several home-invading weevils that come into our homes in April through November.

They are harmless to humans and structures.

More info

Cydia pomonella

Codling Moth is a major pest of apple, pear, and walnut trees in North America.

In Montana, moths emerge from pupae in spring, mate, and lay eggs. Larvae hatch, burrow into fruit, and feed on the developing seeds. Mature larvae exit fruit, travel down the trunks of trees to spin cocoons and either overwinter or pupate after a few weeks to produce a second generation of moths in late summer.


Managing Codling Moth in Montana Commercial Orchards

Managing Codling Moth in Montana Home Orchards

Montana Codlng Moth Trap-Based Biofix Compared to Two Fixed Biofix Models

Montana Surveys of Codling Moth Damage to Apple Fruit

The White Pine Weevil which kills the tops of conifers, is the most serious ecomonic insect pest of white pine in Maine. Weevil attacks result in trees that are multitopped, crooked, and of much lower value for sawtimber.

Appearance and development of ornamental trees are also affected. Trees in open areas, plantations, and forest clearings are most severly damaged.

White Pine Weevil most commonly attacks Eastern White Pine, Jack Pine, and Norway spruce.

However, many other pines and spruces, including ornamentals, are also susceptible.

Finish Reading Article

The most common ticks in Montana are the Rocky Mountain Wood Tick, Dermacentor Andersoni, and the American Dog Tick, Dermacentor variabilis. The two species look very similar.

We no longer have either of the two species of black-legged ticks (formerly deer ticks) that vector Lyme disease in Montana.

The Rocky Mountain Wood Tick transmits Rocky Mountain Spotted Fever and Colorado Tick Fever. RMSF transmission is rare in our state.

Read more about Diseases, Prevention, and Removal

More articles

Ticks of Veterinary and Public Health Importance in Montana

Diseases Vectored by Ticks

Information from CDC

Homeowners and producers enduring occasional pest outbreaks often over-rely on chemical management strategies or react after pests can be managed effectively.

Pest management using multiple methods, otherwise known as Integrated Pest Management (IPM), is a strategy combining a wide range of tactics, including biological, chemical and cultrual practices to provide long term, environmentally sustainable, and economically feasible control.

Pest Resistance

Pesticides became increasingly ineffective at managing many pests due to overuse. Pest resistance is defined as the ability of a pest to tolerate a pesticide that once controlled it.

Resistance takes place due to repeated pesticide applications using one chemical mode of action, thus selecting for survivors with an inherent genetic advantage to the chemical applied.

Resistance: The ability of a pest to tolerate a pesticide that once controlled it.

Loss of Beneficial Organisms

The overuse of broad - spectrum insecticides negatively impacts many beneficial arthropod species.

Beneficial species are often referred to as "natural enemies". There are various parasites, predators, and pathogens that reduce pest populations.

The use of broad - spectrum insecticides may decrease the survival of many natural enemies, thus causing a second pest outbreak, or a resurgence of the original pest.

Persistent Pesticides Impacting Non-Target Sites

Even though pesticide applications may not impact non-target sites initially; persistent chemistries may eventually move to non-target areas. Non-target injury may include losses to future susceptible crops, water contamination through movement via leaching or runoff, or bio-accumulation, or bio-magnification in the environment.

More included information:

  • Integrated Pest Management
    • Biological control
    • Chemical control
    • Cultural control
    • Genetic control
    • Mechanical control
    • Regulatory control
  • Implementing an IPM Program

Read full MontGuide


Monthly Weed Post, February 2020

Some people assume that all thistles are bad, and the only good thistle is a dead thistle. There are five exotic and ten native thistle species in Montana. Exotic thistles can spread quickly, they have poor forage value, and their sharp spines can injure livestock and limit recreational activities. In contrast, native thistles are rarely invasive and play an important role in the exosystem. For example, birds feed on thistle seed, and some birds time nesting around thistle flowering and use the downy seeds to line their nests. Bees, wasps, flies, and beetles feed on thistle pollen and become food storage for other wildlife, and some native thistles are forage for deer and elk. Thistles can even be eaten by humans (check out the story of Truman Evert and the 1870 Yellowstone Expedition)! Finally, native thistles fill a niche in plant communities. Consider native wavyleaf thistle, Cirsium undulatum, which may occur on roadsides. It's often sprayed because it's assumed to be weedy and exotic; once removed the resulting open niche may be filled by a noxious weed that is hard to control.

How to tell whether a thistle is exotic or native can be challenging, MSU Extension has a Guide to Exotic Thistles in Montana and How to Differentiate from Native Thistles. It includes a dichotomous key and pictures to illustrate thistles that grow in Montana. Get started by answering the following questions:

  1. Does the thistle have rhizomes or a taproot?
    • Rhizomes... It's probably the exotic Canada thistle (Cirusium arvense), the only strongly rhizomatous thistle in Montana. Heads are small and clustered, and there are no spiny wings on them.
    • Taproot... Continue to question 2.
  2. Does the thistle have spiny wings the entire length of the stem?
    • Yes... It's one of four exotic thistles. Review key diagnostic features and photos.
      • Bull Thistle (Cirsium vulgare). Narrow, needle-like bracts, green foliage.
      • Musk thistle (Carduus nutans). Broad triangular bracts point outward or down, headsoften nodding.
      • Plumeless thistle (Carduus acanthoides). Flower heads in clusters on short stalks, bracts collectively <0.8 inches high
      • Scotch thistle (Onopordum acanthium). Silver gray foliage, plants grow up to 12 feet tall, spiny wings especially prominent
    • No... It's probably a native thistle. See descriptions in the MSU Extension thistle guide.

Need help? Send a photo (a less painful option than sending a plant!) to your local Extension Agent or the Schutter Diagnostic Lab.

Further Information

For more information on this month's Weed Post, contact Extension Invasive Plants specialist Jane Mangold. Past posts are available in the Monthly Weed Post directory.

The Printable PDF version of this post includes a crossword puzzle.

Revised 5/17

This MontGuide describes henbane's biological and ecological characteristics. It also provides mechanical, cultural, and chemical management options to control this species.

Black Henbane (Hyoscyamus Niger L.) is also known as common henbane, fetid nightshade, hogbean, hogbane, insane root, and stinking nightshade.

It is an invase weed that has become an invader of pastures, meadows, and roadsides throughout the United States. In western pastures and meadows, it can form dense strands that replace other vegetation and decrease forage production and plant diversity. A land manager's abiity to correctly identify black henbane and understand the plant's life cycle and growth requirements is importatn in selecting management strategies that effectively suppress its populations and promote healthy desired vegetation.

Origin and Distribution

Black henbane is native to Europe and northern Africa where it was cultivated for its medical qualities. It was likely introduced to the United States in the 17th century as a medicinal and ornamental plant.

Black henbane has since escaped cultivation and spread throughout much of the United States, particularly in the Northeast, Midwest, and the Rocky Mountains.

Black henbane does well in most soils and will grow in a variety of environmental conditions. The plant is primarily found in sandy or well-drained loam soils with moderate fertility and does not tolerate water-logged soils.

Black henbane is common in disturbed open sites in rangeland and pastures, along fence rows, roadsides, riparian areas, and waste areas. It is also found on heavily grazed sites. Its growth is enhanced by increased levels of soil nitrogen.

Identification and Biology

Black henbane is an annual or biennial of the nightshade family that reproduces solely through seed production. Seed germinate and develop into a rosetter in late May. The plant grows 1 to 6 feet tall. It flowers from June to September, with peak flowering usually in July. Black henbane produces 10,000 to 500,000 seeds per plant. Black henbane has an unpleasant odor at all growth stages, especially when it is crushed.

Impacts of Invasion

The full extent of ecological, economical, and sociological impacts of black henbane are not well documented. The plant is capable of forming dense infestations, replacing desirable native species, impacting agricultural production, and reducing plant biodiversity. Black henbane is narcotic and poisonous to humans and livestock. All parts of the plant are poisonous. Livestock will usually avoid it because of its foul odor and bitter taste, unless other forage is unavailable.

Integrated Management

Management objectives for black henbane control should involve preventing seed production and periodically monitoring populations. Field observations suggest the seeds of black henbane can remain viable in the soil for a period of five years; therefore, particular attention is required for several consecutive growing seasons to control newly emerging plants. Good vegetative cover of desired plants considerably reduces the change of black henbane infestation.


The most effective method of black henbane management is preventing its spread and establishment. Limiting weed seed dispersal, containing current infestations, minimizing soil disturbances, detecting and eradicating new plants, maintaining competitive desirable plants, and grazing properly will help reduce the establishment and spread of black henbane.

Preventing seed production from year to year is critical.


Grazing to control black henbane is not an option because it is poisonous to livestock, poultry, and swine.


Cultivation prior to seed production may be used to control black henbane. Cultivation must be repeated annually until the seed bank is depleted.

Pulling or digging isolated plants or small infestations prior to seed production can be an effective means of controlling this plant if the entire taproot is removed. If pulling, gloves and protective clothing are strongly recommended to prevent skin irritation. Because of its thick, tough stem, and roots, black henbane can be difficult to hand-pull.


Black henbane with mature fruits can be burn to kill seed and reduce seed spread.


Repeated mowing prior to seed production can be effective control.


Several herbicides are listed as providing control of black henbane. (Click here to view pesticide table). Herbicide recommendations very by region and site.


There are no biological control insects or pathogens available for black henbane.

To read the full MontGuide about Henbane click here

Tanacetum vulgare

Common tansy has a long history of medicinal use but has become a problem weed in pastures and along roadsides, fence lines, and stream banks.

Also known as golden buttons and garden tansy.

Is a perrenial herb in the sunflower family.

The plants contain alkaloids that are toxic to both humans and livestock if consumed in large quantaties.

Cases of livestock poisoning are rare, though, because tansy is unpalatable to grazing animals.

Common Tansy info

Waterhemp is a very problematic weed that causes extreme yield losses in crop fields in other parts of the United States and Canada.

Waterhemp is widespread in cropping systems in the Midwest.

Has recently been documented in Montana

Water Hemp Info

Ventenata is a winter annual grass native to Southern Europe, Western Asia, and Northern Africa. It is also known as wiregrass or North Africa grass.

Ventenata is typically 6 to 27 inches tall with leaves that are rolled lengthways or folded.

It has open sheaths, and the inflorescence is more or less lax, open, and pyramidal in shape.

The color of ventenata has been described as tawny to light yellow.

Lives in roadsides, hay, pastures, range, CRP fields in the Western U.S.

Check out this 60-second video on key features of what to look for!

Identifying Ventenata Early in Summer

There are studies being done right now for a potential Biocontrol Agent for Canada Thistle

The research is just beginning to assess how well the rust reduces Canada thistle patches.

Informational Documents:

Montana Biological Weed Control Coordination Project

Reach Out to Us

Send your samples to the Schutter Diagnostic Lab

Preventing Palmer amaranth from establishing and becoming a troublesome weed in Montana is a high priority.

Palmer amaranth is a problematic broadleaf weed in the pigweed genus. Pigweeds are common in agricultural fields around the world. Pigweeds are warm season annual plants that grow quickly and aggressively, compete with crops, and reproduce through prolific seed production.

While Palmer amaranth has not been found in Montana, a number of pigweeds are weedy here, including redroot pigweed (A. retroflexus), mat pigweed (A. blitoides) abd tumble pigweed (A. albus). Of the three, red root pigweed is the most common in croplands.

Palmer amaranth has characteristics that make it more problematic than other pigweeds, including rapid growth, prolific seed production with hundreds of thousands of seeds per plant, and resistance to multiple herbicide modes of action.

It was ranked as the most problematic weed in the United States in 2016 and has had enormous economic impacts in southern states.

Palmer amaranth continues to expand its range, causing major yield losses in a variety of crops.


Seedings and Vegetative Characteristics

Distinguishing among pigweed plants can be difficult before they produce flowers. Palmer amaranth's stem is reddish and smooth with no hairs.

Palmer amaranth leaves are alternate and grow symmetrically around the stem like most pigweeds. Leaves tend to be more elliptical (egg-shaped).


Palmer amaranth is dioecious, meaning there are seperate male and female plants. The long flowering stems of female Palmer amaranth plants make the distinct from redroot pigweed.

The male and female inflorescence is terminal, meaning it occurs at the end of the stem, and is usually very elongated. Spiny bracts surround the female flowers and flower clusters are spinier to the touch than redroot pigweed. The female inflorescence is generally thicker than the male inflorescence and can be easily identified by rubbing it.

Read full MontGuide

Crop Diseases

Ascochyta blight of chickpea is highly prevalent statewide in Chickpea.

We have also found Botrytis and significant root rot issues.

Read more about crop diseases!

Crown Rust or leaf rust of oats is caused by the fungus Puccinia coronata var, avenae.

Crown Rust infects the Illinois oat crop almost every year.

Several specialized varieties of the fungus attack many related grasses.

The amount and severity of infection varies greatly from year to year, depending on weather conditions, the amount of rust inoculum ( spores ) present, and the acreage of susceptible varieties.

Other articles to check out about Crown Rust

University of Minnesota Cereal Rust Lab

US Scab Initiative

Top Crop Manager

Prevention Article

Stripe rust can occur anywhere in the U.S. and Canada, causing substantial yield losses when conditions are favorable.

Stripe Rust is caused by Puccinia striiformis and is also known as yellow rust.


  • Starts as yellowish flecks on leaves.
  • On sesceptible varieties, pustules containing yellow-orange spores erupt from leaves.
  • Pustules are clustered on seedling leaves, while pustules on mature leaves occur in a linear, stripe-like pattern.
  • Later in season, yellow-orange fungal spores turn black and remain attached to a leaf tissue.

Stripe Rust pustules form a noticeable striped pattern on mature leaves and are more yellow than stem rust spores.

Check out these articles for even more information:

Stem, Leaf, and Stripe Rust Resistance in Wheat

Stripe Rust of Wheat

Fusarium head blight is a disease of wheat and barley.

The pathogen reduces yield, seed quality, and produces a vomitoxin called DON.

The primary symptom of the disease is bleaching of some of the florets in the head before maturity.

Severe infections can cause premature blight or bleaching of the entire spike or head.

Read more with these articles!

US Wheat and Barley Scab Initiative

NDSU Guide


Pulse Crops are annual dry grain legume crops that help fix atmospheric nitrogen, they are drought and heat tolerant, and have a positve impact on the yield of subsequent crops through the changes in soil.

The main pulse crops produced in the Northern Great Plains are field pea, lentil, dry bean, chickpea, faba bea, and lupine.

The Root Rot disease complex of pulse crops causes damping-off, seeding, blight, root rot, and reduces stand establishment, nitrogen fixation, root distribution, and root vigor.

Uneven planting caused by poor germination and seedling blight are also results from Root Rot.

If you are wanting even more information or are worried about Root Rot in your fields, please contact Mary Burrows at [email protected]; 406-599-9966; @MontanaCropDoc

There are several viruses of wheat and barley in Montana that can economically important.

Wheat Streak Mosaic Virus

  • occures in all wheat-growing regions worldwide and can infect winter and spring wheat, durum, barley, corn, and many other grass species.
  • Symptoms are yellowing of the leaf in a streaked or stippled pattern.
  • Severely infected seedlig plants may appear lemon yellow and can be confused with nutrient deficiency or cold damage.

Wheat Curl Mite

  • Another common mite on wheat
  • Not easily seen with the naked eye, but when present in high numbers can make the wheat leaf curl so that the upper surface is rolled inward.
  • Small white, cigar-shaped mite

Links with more info!



Ascochyta blight is a rapidly spreading disease that is favored by cool, wet conditions.

Because the disease can spread very rapidly, producers should spray crops twice. Once at the first sign of the disease.

Early symptoms are circular lesions with black specks that are visible with a magnifying glass.

Lesions appear on leaves and stems. Stem girdling and breakage can also be present.

Articles on Ascochyta

Extension Plant Pathology Website

Ascochyta Blight in Chickpea

Fungicide Table


Fungicides have become an essential tool for growing high yielding, top-quality crops in Saskatchewan.

However, with increased fungicide use year after year, resistance (insensitivity) within some of the main pulse crop diseases has begun to emerge.

Awareness of potential insensitivity issues, in-depth understanding of fungicide groups, proper fungicide use and rotation, and integrated disease management strategies are required in order to delay further development of fungicide insensitivity.

Fungicide Insensitivity in Pulse Crops

With the recent weather, disease conditions are very conductive on all crops.

Katie H likes to say "high yields potential means high disease potential" and it isn't a lie!

Here are a few tools to aid in fungicide decision making:

Fungicide Use in Field Crops: Benefits and Risks

Foliar Fungicides for use in Pulses

Foliar Fungicides for Use in Wheat

Fungicide Decision Tool

YouTube Video

Other Interesting Articles

"Montana's Real Treasure"

Growing Lentils organically can improve our soil and increase producer incomes.

Lentils are good food - satisfying, nutritious, and delicious!

Lentils are high in fiber, essential nutrients, and phytochemicals.

Eating lentils can improve our health and prevent chronic diseases like heart disease, diabetes, and cancer.

Cooking with lentils is simple and inexpensive.

Observation from the Road: Lentils

Get Ready to Scout for Cutworms

Wet Soil Conditions Favorable for Wireworms

Visit this website for more information:

Soil Testing

or Contact

Monica Brelsford

[email protected]

Carmen Murphy

[email protected]

Mary Burrows

[email protected]

Environmental stress in trees can be present in many ways:

  • Changes in the tree canopy
  • Early onset fall coloration
  • Interveinal chorosis of varying degrees.

These symptoms can also indicate potential pests adn pathogens, so it is important to rule those out before managing for chlorosis.

To read more about Tree Stress symptoms and management click this link:

Stressed Trees

How to know if yuor garden has been injured by herbicides:

  • You may see extreme cupping and twisting of leaves
  • Twisting and/or cracking of stems
  • General distortion of plant leaves
  • Leaves may feel thicker than normal
  • May have veins that look more parallel than usual

Commonly these symptoms can come from other sources including:

  • Herbacide drift
  • Insect or disease issues ( if symptoms are not widespread)

Our recommendation is to never injest produce that has herbicide injury symptoms. Especially if you are unsure of the herbicide that is responsible.

Additional Resources:

Understanding Herbicide Contaminated Soil Amendments for Greenhouses, Nurseries, and Home Gardens

How to Prevent Non-Target Injury of Broadleaf Crops

Minimizing Pesticide Contaminated Soil Around the Home and Garden

Fairy Rings are dark green areas of grass or turf that form a circular or semi-circular pattern, orccasionally, with areas of slow-growing or dead turf.

Mushrooms can form in the dark green rings.

Fairy rings range from 3ft to over 100 ft in diameter.

Fair rings in lawns are usually formed by the fungus, Marasmius ordeades, referred to as the fairy ring mushroom.

Fairy rings are formed by fungi that live in the soil and break down dead, organic matter.

Read more on Fairy Rings.

Master Gardener Q & A

Fire Blight is a bacterial pathgen that infects flowers of pear, apple, and other members of the Rosaceae family.

Symptoms include dead branches, water-soaked blossoms, light brown to blackened leaves, discolored bark, black "Shepherd's Cook" twigs.

The development of the shoot blight is dependent upon the existence of wounds at the shoot tips and the dissemination of the fire blight pathogen to those tips.

The initial symptom of shoot infection is flagging or wilting of the shoot tips.

The bacteria can rapidly spread through the plant killing both the scion and rootstock of susceptible cultivars and rootstocks.

Young trees are particularly vulnerable to the disease which thrives under warm and humid conditions.

Fire Blight 2020

Tool to Assess Your Fire Blight Risk

After an early cold snap, give trees time to recover.

A good way to see if your tree is still alive is to use your fingernail to shallowly scrape into the cambium of the branch. If it still green, the branch is still alive and just needs time to recover.

Read Full Article

How to Help Plants Prepare for Winter

Asian Giant Hornet is the largest hornet species in the world and ranges from 1.5" to 2" long and can be distinguished from other similar species by their large size and yellow-orange head.

AGT only nest in the ground, unlike other species of wasps and bees.

AGH feed on other insects for food and do not ususally attack humans unless provoked.

They have been known to target honey bee hives, particularly in July - November.

Murder Hornets... Fact or Fiction?

Report Sightings to the Montana Department of Agriculture

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