Late Blight Spotted

Oh, no. Not again!

Authorities don’t know yet if Late Blight could repeat its 2009 devastation of tomatoes and potatoes  in 2010, but it WAS  detected last week in a greenhouse in St. Mary’s County.   The University of Maryland issued a warning about it, which includes this good advice:

What can I do now?

  • Educate yourself: check out our photos, video, and Q&A on this page.
  • Be observant and vigilant! Closely examine tomato transplants prior to planting. After planting, monitor your tomato and potato plants closely for symptoms of the disease.
  • Any pieces of potato from last year’s harvest should be dug up and removed now! That goes for any volunteer potato plants and seed pieces as well. Do not plant any store-bought potatoes or potatoes from gardens that were infected last year with late blight. Volunteer tomato plants do not need to be removed but should be monitored for late blight symptoms.
  • Contact the Home and Garden Information Center (HGIC) by phone (1.800.342.2507) or e-mail if you believe you have late blight. If possible, include a close-up photo of suspected late blight infections. We may ask you to send in a sample of your plant. Don’t send a sample unless you have talked to someone at HGIC.

Should I spray my tomato and potato plants with a fungicide?

  • HGIC does not recommend that gardeners spray fungicides at this time. We will recommend fungicide applications if we begin to receive reports confirming that the disease is active in home or community gardens.
  • Fungicides containing the active ingredient chlorothalonil are effective for controlling late blight. Fungicides containing mancozeb are also labeled in MD for use by gardeners to control this disease. Fixed copper is less effective but probably the best choice for organic gardeners. In all cases, you must apply the fungicide prior to infection for it to be effective.

Here’s lots more information about Late Blight in their Disease Diagnostics section.

Another Reason to Buy from the Independents?
I can’t resist adding that most news reports of last year’s Late Blight traced it to a single grower (Bonny’s), which supplies the big box chains like Home Depot and Lowe’s.  Here’s the story in the New  York Times.

Posted by Susan Harris Susan Harris

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