We have completed pathogenicity and fungicide assays of Pythium lutarium, P. oopapillum, P. torulosum, and P. sylvaticum with strains collected from soybean and corn in Iowa. Twelve isolates that are representative of four species of Pythium, P. lutarium, P. oopapillum, P. torulosum, and P. sylvaticum, were screened for sensitivity to fungicides in a Petri dish assay. Fungicides evaluated include metalaxyl (Allegience), ethaboxam (new fungicide from Valent), azoxystrobin (Dynasty), pyraclostrobin (Headline), trifloxystrobin (Trilex), captan, and thiram. We have shown that temperature affects pathogenicity and fungicide sensitivity. This is the first time temperature has been reported to affect fungicide sensitivity and implies that soil temperatures at planting could influence the efficacy of a seed treatment depending on the pathogen profile of the field.

Four presentations detailing results of this research were given to approximately 2000 stakeholders in Iowa at various ISU Extension and Outreach programs. Furthermore, a trifold publication entitled ‘Scouting for Pythium root rot of soybean’ that describes this seedling disease was distributed to 12 North Central states and Ontario, Canada.