An update on Late Blight from Becky Sideman, UNH Cooperative Extension:
Yesterday we received notification from Meg McGrath (plant pathologist, Cornell University) that late blight was just identified in an early-planted potato field on Long Island. The farmer has destroyed the plants showing symptoms and has applied fungicides to protect the remainder of the plants.
According to Meg, the plants showed large brown classic late blight leaf spots; and a very few stems had large brown spots. She believes that the outbreak is due to contaminated seed. Two varieties with symptoms are Dark Red Norland and Superior; seed from Maine.
At this point, we are not concerned with spread of late blight from this initial site in Long Island. However, it is VERY important to scout your potato plantings for late blight symptoms, regardless of where seed was purchased.
Good resources with photos of symptoms and detailed discussions of how to manage late blight include:
If you suspect late blight, please take photos and send to Cheryl Smith (firstname.lastname@example.org), myself (email@example.com), and/or your county Extension field specialist. Any questions, please contact any of us.