This year Common Rust is present in many fields, and we have seen the start of Grey Leaf Spot (GLS). Northern Corn Leaf Blight (NCLB) has been slow to develop in Southern and Central Iowa, partially due to warmer temperatures, however I have seen some NCLB in Northern Illinois, where it was cooler and wetter. Due to the recent moisture and humidity, I expect this will be a year with a high incidence of disease, including GLS. It also is a year where leaf tissue is at a premium, due to smaller total leaf area than normal. I am inclined to apply Headline AMP® or a similar fungicide in most corn and bean fields this year. I especially would consider applying fungicides to fields with high residue, fields following cover crops, corn-on-corn fields, low lying fields, or poorly drained fields. I also would apply fungicide to hybrids which are more fungicide responsive for yield and standability. A greater economic advantage exists for fungicide application, if you already need to apply an insecticide. We feel the ideal time to spray a fungicide on corn is around the first brown silk. However if CRW or Japanese Beetle clipping of corn silk occurs, I would apply the fungicide with an insecticide during flowering. Avoid using an adjuvant if applying fungicide before full silk.
Soybean diseases could be prevalent this year in areas with excess rain and fungicidal control may be justified, because we must preserve the limited soybean leaf area in 2017. White mold (WM) could be a problem in wetter fields, but WM may be reduced this year, as it appears soybeans could breathe better since soybeans are generally not be as big as normal.. Due to the high level of SDS last year, continue to monitor fields that are wet during early flower for SDS. SDS management involves seed treatments (Clariva® and ILevo®), improved drainage, and planting highly tolerant varieties such as 3155CRR2 and 2659CLL. We focus heavily on launching improved SDS and white mold soybean varieties.