Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Reporting on July 7th: If soybeans are flowering and the area between rows is filled in more than 50%, white mold infection risk is just moderate in most locations of the state, with the exception of the far northeast portions of the state. This moderate risk indicates that there may not be apothecia present in fields in these locations at this time, however, the situation needs to be monitored closely as we move from R1 to the R2 growth stage. With a cooler, wetter weather pattern over the next 5-7 days, I believe that the risk for white mold will increase. I’m expecting a later onset (closer to the R3 growth stage) of white mold for much of the state in 2021. Warmer weather up to this point has pushed the risk of white mold potentially later in the bloom period.
As for corn, the present risk of infection for tar spot is high for much of the state. Cooler, wet conditions over the next week will keep risk moderate to high. We have scouted several locations in Wisconsin and have been unable to find tar spot at this time in the state. However, figure 3 shows that tar spot has been found in some surrounding states, at low levels.
Read my full report here: