Late blight has been confirmed on tomato today from Waukesha County. Dr. Brian Hudelson in our Plant Disease Diagnostic Clinic confirmed the disease and my lab is working on identifying the clonal lineage (or strain type) yet this afternoon. More information will come as we learn more.
Please be vigilant in observing initial symptoms and be thinking about fungicide selections and intervals as this find does indicate that conditions have been favorable for disease within our state.
The Plant Disease Diagnostic Clinic is taking in free late blight samples for potato and tomato. More info on the clinic is here: https://pddc.wisc.edu/
More information on last blight and an updated list of fungicides for use in conventional potato is provided at link below.