Date of this Version
Wulkop Gil CA, Nieto-Lopez E,Everhart SE (2020). Fungicide Sensitivity of Sclerotinia sclerotiorum Isolates Selected from Five Different States That Use Different Fungicide Treatments. Poster presentation, UCARE Research Fair, Spring 2020, University of Nebraska-Lincoln.
Sclerotinia sclerotiorum is a plant pathogenic fungus that causes a disease called white mold that can infect more than 450 plant species including soybeans, dry beans, green beans, canola, and sunflower. This pathogen is capable of up to $252M in losses every year (U.S. Canola Association, 2014). Fungicides are widely used in developed agricultural systems to control disease. However, resistance to the most effective fungicides has emerged and spread in pathogen populations and there have been multiple reports of S. sclerotiorum isolates becoming resistant to certain fungicides. Since different fields in different states use different fungicide treatments on plants and different numbers of applications depending on environmental conditions, we hypothesize that isolates with the lowest fungicide sensitivity will be those that come from fields with more intensive fungicide applications. We aim to determine the fungicide sensitivity of S. sclerotiorum isolates from five states to assess the risk of resistance. Isolates were selected from dry bean fields from five states from the selection of isolates in the Evertart lab. Isolates were screened against boscalid, tetraconazole, picoxystrobin, and thiophanate methyl fungicides using discriminatory concentrations previously determined by members of the Everhart lab, and their EC50(D) was calculated. Differences in EC50(D) in different states hints at S. sclerotiorum developing resistance to commonly used fungicides. However, the hypothesis was only partially supported by the data since the baseline isolates (isolates that have never been exposed to fungicides) EC50(D) is not the lowest for all fungicides.