Curcurbit downy mildew alert

The current risk for cucurbit downy mildew (CDM) in New England, including southern NH, is moderate according to the CDM IPM forecasting model:

…BUT…a tropical storm is moving up the coast and CDM is active in PA.  

It is likely that the risk will be high by later today (Friday 7/10/2020) or tomorrow (Saturday 7/11/2020). 

Cucurbit producers (cucumbers, melons, summer & winter squash) should have protectant fungicides for CDM on prior to the arrival of the storm. These are listed in the New England Vegetable Management Guide - go to the crops tab and select the appropriate cucurbit crop(s). Chlorothalonil or copper products (organic options) are protectant fungicides that most growers probably already have on-hand.

Monitor your crops after this system moves through. If you suspect you have CDM infections, Please take photos and submit them to Once CDM occurs in our area it will be important to switch from protectant fungicides to fungicides with specific activity against CDM.

The Extension Fruit & Vegetable team.


Cheryl Smith
Plant Health State Specialist
Phone: 603-862-3841
Office: Cooperative Extension, Spaulding Hall, Durham, NH 03824