According to the latest update from Eugenia Banks, potato specialist with the Ontario Potato Board, a second outbreak of late blight was found in a tomato field in Pierce County, Wisconsin. The first outbreak was found on a potato field in Adams County, three hours west of Pierce County.
According to the University of Wisconsin-Madison, the infection is about one week old, based on the symptoms.
In Ontario, as of August 21, late blight spores have not been detected in spore traps across the province. Although there have been wet periods favourable to disease development, Banks continues, late blight has not been found because the inoculum is not present so far.
Early blight concerns for Ontario
However, potatoesincanada.com reported on Banks adding that early blight is a concern for Ontario growers. On August 20, during a field visit Banks observed a lot of early blight in an area of a field that had not been irrigated.
“The infection was so severe that many stems had early blight lesions which can be confused with late blight lesions,” Banks says. “The field will be top killed tomorrow, [and] I will keep an eye on infected tubers,” Banks adds.