Poster

Joseph Chonza ¹, Isaack Kikway ¹, and Pierce A. Paul ¹
1. The Ohio State University, Wooster, OH, USA
Corresponding Author: Pierce A. Paul, paul.661@osu.edu

Chonza, Joseph

chonza.1@buckeyemail.osu.edu

Fusarium head blight (FHB), caused primarily by the fungus Fusarium graminearum, reduces wheat yield and grain quality by contaminating grain with mycotoxins such as deoxynivalenol (DON). Researchers developed an FHB Risk Assessment Tool using pre-anthesis weather variables to predict the probability that FHB will exceed the 10% index (IND). These predictions are used to help guide fungicide applications at anthesis for FHB and DON management. However, the tool was not designed to predict DON concentration at harvest. Predicting DON contamination would help inform grain harvest, handling, and marketing decisions. A common question is whether FHB risk predictions at anthesis can reliably predict end-of-season DON contamination in grain. Here we examined associations between naturally occurring end-of-season DON contamination of grain, predicted FHB risk probabilities, and post-anthesis relative humidity (RH) and Temperature (Temp.) summaries. Data were obtained from wheat field experiments conducted in Ohio during all but one growing season from 2015 to 2025. Mean, maximum, and minimum Temp and RH; number of days with RH greater than 90%; and mean rainfall and number of rainy days were summarized over five post-anthesis windows (0-7, 0-14, 0-21, 0-28, and 15-30 days) and correlated with DON. DON was positively correlated with predicted FHB risk probability (r = 0.58, P < 0.001; n = 56). Significant associations between DON and weather variables were observed primarily during the first 21 days after anthesis. DON was positively correlated with Temp variables, particularly maximum Temp during the 0-7-day after anthesis (r = 0.28, P = 0.038), 0-14-day after anthesis (r = 0.35, P = 0.009), and 0-21-day (r = 0.31, P = 0.019) post-anthesis windows. In contrast, DON was negatively correlated with mean RH during the 0-7-day (r = -0.46, P < 0.001) and 0-21-day (r = -0.33, P = 0.014) post-anthesis windows and minimum RH during the first 7 (r = -0.44, P = 0.002) and 21 (r = -0.42, P = 0.004) days after anthesis. None of the tested rainfall variables were correlated with DON and no significant correlations were observed between DON and the tested weather variables during the 0-28- or 15-30-day post-anthesis windows. These findings will form the basis for developing models to predict DON contamination based on predicted FHB risk and post-anthesis weather.

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