Skip to main content

Be on the lookout for basil downy mildew

From Margaret Tuttle McGrath, Department of Plant Pathology and Plant-Microbe Biology, Long Island Horticultural Research & Extension Center:

Reminiscent of the late blight outbreak of 2009, basil plants with downy mildew are being found at big chain garden centers on Long Island, New York as well as in Connecticut, New Jersey, Tennessee, Wisconsin, and several locations in Ontario. And I’m getting reports of the disease from gardeners, in some cases associated with purchase of locally-produced plants at local nurseries rather than big chains (one case here on Long Island).

I’ve also gotten reports recently from Florida, Delaware, Virginia, West Virginia, Kentucky, North Carolina and a grower in Maine.

Please be on the lookout for this disease. If you have an opportunity to visit a garden center to look at basil, I’d appreciate hearing what you see. State inspectors here are done looking in garden centers.

Below are pictures of symptoms on potted plants for sale to gardeners. The last image of a yellowing leaf (on right) is more typical than the first image with collapsed leaves. Like the late blight pathogen on tomatoes and potatoes, this downy mildew pathogen produces an abundance of spores easily dispersed by wind. (See second image below.)

You can see more images on my Vegetable Disease Photo Gallery website. I also have more information and images at the Vegetable MD Online website.

basil-downy-mildew1

basil-downy-mildew2x640
Click for larger view.

Basil Downy Mildew-yellow leaf_2394 CROP

Comments

  1. Donna Simmons says:

    Currently dealing with Downy Mildew on my basil plants in Santa Barbara County, CA.

  2. Jim K says:

    can you do anything besides throw out the basil effected. My basil is screaming…..

  3. cdc25 says:

    Margaret Tuttle McGrath, Department of Plant Pathology and Plant-Microbe Biology, Long Island Horticultural Research & Extension Center replies:

    Best is to get rid of the plants, especially if a lot of diseased leaves as sounds like in this case.

    I think the best option for managing basil downy mildew for gardeners is to grow at least some of the plants in pots that can be brought in at night, and maybe also on rainy days. That is what I am doing this season.

    The pathogen needs high humidity in order to infect. Humidity often get above 85% at night outdoors but not in our homes, especially when we are running air conditioner.

Speak Your Mind

*

Skip to toolbar