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 firstname.lastname@example.org