Please see the following, reprinted from UMass Veg Notes:
Late Blight (Phytophthora infestans) Confirmed in LA, MD, and Northwestern PA
Isolated outbreaks of late blight have been confirmed in Louisiana, Maryland, and Northwestern Pennsylvania. The original source of inoculum has not yet been identified. Given the season last year, chances are good that P. infestans inoculum may have overwintered in infected potato tubers. The Pennsylvania Department of Agriculture has been screening tomato transplants destined for the retail and wholesale markets and so far those samples have been negative. Several other suspect samples have been submitted to their Plant Disease Clinic and those have also been negative. We have had no confirmed cases of late blight in MA this year. The largely dry weather pattern over much of the state is not conducive to the spread of the organism that causes this disease, but it is critical to scout not only this year’s tomato and potato crops but also last year’s potato fields where infected tubers may have survived the winter and are sprouting infected volunteer plants. Early identification and eradication of inoculum sources will help to reduce the likelihood of an outbreak later in the season if the weather favors disease development (rainy, cool, cloudy) for an extended period of time.
If you think you may have late blight in your crops or on volunteer potato plants in old fields, please contact your county UNH Cooperative Extension office or the UNH Plant Diagnostic Lab at (603) 862-3841.
Assoc. Ext.Professor, Sustainable Horticulture
G48 Spaulding Hall, Durham NH 03824
Durham NH 03824
(P) 603-862-3203 (F) 603-862-2717