Cucurbit Downy Mildew is on the move


It’s that time of year again. Cucurbit downy mildew is on the move and the extension pathologists involved in the Cucurbit Downy Mildew ipmPIPE project had our first conference call this morning. To date outbreaks of downy mildew have been reported on a variety of cucurbits in Florida, south Georgia, eastern North Carolina and south Texas. To track current and future outbreaks, see So far I have not had any reports of downy mildew on cucurbits in Louisiana, but county agents and growers should be on the alert as we generally first see the disease show up toward the latter part of June. Although the pathogen doesn’t attack the fruit, it can cause severe defoliation exposing the fruit to sunburn. If we get into a period of rainfall like we had a week or two ago, the disease could develop rapidly. With this in mind, it might be advisable to have growers begin applying preventative fungicide sprays on a regular basis now. For information on the efficacy of fungicides registered for the control of cucurbit downy mildew, see page 194 of the 2010 Southeastern US Vegetable Crop Handbook at For photographs and more information on cucurbit downy mildew, see the Louisiana Plant Pathology fact sheet at


About Don Ferrin

I am an associate professor and extension specialist in the Department of Plant Patholgy & Crop Physiology with the LSU AgCenter in Baton Rouge. I have statewide responsibility for issues and educational programs related to diseases of all horticultural crops in Louisiana.
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3 Responses to Cucurbit Downy Mildew is on the move

  1. Robert Turley says:

    In Calcasieu Parish we have had calls and samples in of Southern Blight on tomatoes and peppers this season. I was wondering if anyone else in the State is having this problem?

    • Don Ferrin says:

      Yes, Southern Blight has been a major problem on tomatoes this year. Haven’t had too many reports on peppers, but they are definitely susceptible. Saw the most gorgeous SoB on an experimental planting of sugarbeets at Burden! I’ve put in a request with the IR-4 project to look at fungicides for SoB control as we just don’t have anything registered for it other than PCNB, which can only be applied prior to or at transplanting, and Evito, which is primarily a peanut fungicide and hard to find here.

  2. I don’t bookmark sites but i will bookmark this!

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