The disease was found on tomatoes in a small home garden. It was spreading slowly through the planting, probably as a result of the hot, dry weather. In an e-mail, Ivy said Chris Smart, plant pathologist out of Geneva, suspects that spores are probably everywhere by now. Just last week, the blight was confirmed in Syracuse and the Hudson Valley.

The Cornell Extension office recommends that gardeners who intend to spray should start now. Copper is most effective when used as a preventive by organic growers; once late blight establishes, copper cannot stop it. Copper is also harsh to skin and it is recommended that gardeners use it with caution and follow all label directions. Ridomil is an option for conventional gardeners.

Late blight flourishes in wet, cool, windy weather. Ivy wrote that the local extension office is still waiting to hear which strain of late blight has reached the region.

She urges anyone with new infestations, or anything suspicious on tomatoes or potatoes to bring leaf and stem samples, sealed in a plastic bag, to the nearest extension office for testing, at no charge.