Montana State University

Herbicide damage appearing in Montana's vegetable and bedding plants

July 15, 2009 -- MSU News Service

With no sign of diseased leaves or insect infestation, the leaf stunting and gnarled condition of this tomato plant is probably due to herbicide damage. (Photo by Tammy Leino.)   High-Res Available

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MSU News Service
Tel: (406) 994-4571
BOZEMAN -- Montanans are reporting signs of herbicide damage to vegetable and some flower plants. Montana State University's Schutter Diagnostic Lab has received numerous reports in recent weeks of a condition that causes leaves on affected tomato, other vegetable, and flower plants to curl tightly to form "fiddleheads."

Other leaves may cup and have an atypical vein pattern. Stems twist and fuse to form abnormal shapes. Symptoms occur on newer foliage or the entire plant depending on when exposure occurred. There is no treatment available to cure symptoms.

"If soil or compost is contaminated, it cannot be used for vegetable crops or landscape plantings," said Linnea Skoglund, plant disease diagnostician at MSU's Schutter Diagnostic Lab. "To test the soil, plant bean or radish seeds in the medium and if the soil is contaminated, these will show the same distortion symptoms."

The damage can be caused by one of several classes of herbicides - benzoic, phenoxys or pyridinecarboxylic acids (i.e. dicamba, 2,4-D and tordon). These herbicides can persist in the environment for years, if not decades.

"Sources of contamination have been found in mulch, compost, manure, grass clippings, water and ground water, or residual from past use on pastures, which is common in new housing developments," said Skoglund.

Questions can be answered by calling the Schutter Diagnostic Lab at (406) 994-5150.

Contact: Linnea Skoglund (406) 994-5150 or