If you are growing tomatoes or potatoes here is some information you need to know. Late Blight (Phytophthora infestans)—the same disease responsible for the Irish potato famine is showing up this year in northern Illinois (this is not common to Illinois in a normal year.) This disease does not overwinter here, but can "blow in" during the season from other states where it does overwinter. The cool, wet conditions this season have been very conducive to its development, allowing its movement to a larger than normal area.

Homeowners have a few fungicide options for protection of plants not already showing serious signs of infection. Look for fungicides labeled for tomatoes/potatoes with one of the following active ingredients: mancozeb, maneb, fixed copper or chlorothalonil. Be sure the product you buy is specifically labeled for use on vegetables. The label will tell you how long to wait between the time you spray and the time you harvest the tomatoes. If home gardeners have been spraying regularly with one of these active ingredients for control of other common tomato/potato diseases (like Septoria or Early Blight), they should continue their program for continued protection against Late Blight this season.

For more information on this disease go to http://web.aces.uiuc.edu/vista/pdf_pubs/913.pdf. Thanks to University of Illinois Extension Specialist Elizabeth Wahle for providing this information.