Researchers of the University of Wisconsin Extension Plant Pathology alert farmers that a low level of the late blight pathogen, Phytophthora infestans, has been detected in seed potatoes grown in Langlade County, Wis. The seed sample was received on Tuesday, April 12.
Tubers primarily exhibited symptoms of bacterial soft rot. The sample was not randomly collected, but was collected from culled seed tubers prior to cutting.
While late blight was not detected in seed production fields in Langlade County in 2010, there was some late-season late blight activity in the state which may have exposed senescing crops to the spores of late blight. Given the sampling method and size, it is not known how widespread or with what incidence this disease risk may be.
Additionally, the applied testing methods are highly sensitive and the levels of detection were weakly positive, indicating low quantity of pathogen. This notification is to make potato seed and production growers aware of the potential risk of late blight in the 2011 crop.