KindHarvest summary: Soybean researchers warned in 2022 that resistance to foliar fungicides was becoming more widespread. Frogeye leaf spot resistant to QoI, or strobilurin, fungicides had been documented across more than 20 US states, with resistance also emerging in several other soybean pathogens.
What the source reports
University of Kentucky plant pathologist Carl Bradley explained that fungicide resistance can be harder to recognise than herbicide resistance because disease symptoms require close inspection. A multi-active product may still appear effective even when one component has stopped working, placing greater selection pressure on the remaining chemistry.
Only a small number of fungicide chemistry groups are widely used in soybean production. Repeated preventive applications can increase selection pressure, especially when the target disease or yield response is uncertain.
Practical response
The report recommends combining resistant varieties, crop rotation, scouting, weather and disease-risk information, and fungicides applied when conditions justify them. Local extension advice remains important because pathogen populations, crop susceptibility and seasonal risk differ by region.
Related KindHarvest reading
John Kempf’s commentary approaches plant disease from the host, microbiome and growing-environment sides of the disease triangle. Read the KindHarvest brief on deconstructing disease.
Source and credit
This KindHarvest Team news brief is based on reporting by Ginger Rowsey for Farm Progress, published 12 July 2022. Read the current Farm Progress article.