From Meg McGrath, Long Island Horticultural Research & Extension Center, mtm3@cornell.edu:
This disease is developing now on cucumber in western New York (detected in six counties), eastern NY (three counties), and on Long Island, but not yet in central NY. See map at the CDM.ipmpipe.org website. Ontario, Canada, and mid-western states are the source of the pathogen spread to western NY. Source for eastern NY and Long Island is the Mid-Atlantic region (eastern PA, MD, DE, and NJ). Spread to more cucumber plantings is expected when conditions are favorable, in particular during a cloudy day with evening rain.
Risk of downy mildew developing on other cucurbit crops will increase as the season progresses and other strains of the pathogen spread to NY. Cantaloupe typically is affected next. Occurrence on watermelon, squash and pumpkin is more variable. Use new filter feature of map to view location of confirmed cases on specific crops to assess risk.
See previous updates and the cucurbit downy mildew webpage for additional information.