Our colleagues at the UMASS vegetable team just sent this alert at 1pm Friday, 7/24/2020: Cucurbit downy mildew was confirmed on cucumbers in Franklin County, MA this morning. Disease was just starting in one of 8 varieties of cucumber, no other cucurbit crops being grown nearby were affected.
NH cucurbit producers in southern NH counties (Hillboro, Cheshire) should begin using targeted fungicides with activity against downy mildew. Recommended targeted fungicides include: Orondis Ultra, Orondis Opti, Ranman, Omega, Gavel, Forum, Previcur Flex, Curzate, and Presidio. These should be tank mixed with a protectant fungicide, and materials should be rotated according to label instructions in order to delay resistance development. For a complete list of labeled materials updated for this year, consult the New England Management Guide. Producers in other NH counties should be using protectant fungicides, and be ready to switch to targeted fungicides when CDM is found in NH.
Please continue to monitor cucurbit crops. If you suspect you have CDM infections, Please take photos and submit them to firstname.lastname@example.org. Confirmation of infections helps to improve the accuracy of the predictive model.