Late Blight
Welcome to the Late Blight information and update page.
August 24, 2011
Late blight has now been identified in Grafton County in New Hampshire and in several locations in Vermont and Maine. Remember that spores can travel a long distance in cool cloudy weather, but are killed easily in hot sunny weather. Tomato and potato crops should be protected with fungicides prior to the rainy weather expected this weekend. (see the resource list below for suggested 2011 fungicides for tomatoes and potatoes).
** For certified organic growers, fungicide options include Serenade and approved copper formulations. OMRI-listed copper formulations include: Basic Copper 53, NuCop 50WP, Cueva and Champ WG.
Good resources for showing photos of symptoms along with detailed discussions of how to manage late blight include:
http://plantclinic.cornell.edu/factsheets/lateblight/late.htm
http://www.nysipm.cornell.edu/publications/blight/
If you suspect that the disease is present in any of your crops please mail or deliver a sample ASAP for professional diagnosis to your state’s Extension plant pathologist so we can track the disease. In NH mail to: Cheryl Smith, UNH Cooperative Extension Plant Diagnostic Lab, G37 Spaulding Hall, 38 Academic Way, Durham, NH 03824. You can also phone the Plant Diagnostic Lab at 603-862-3200 or call your county UNH Cooperative Extension Office.
Becky Sideman & Cheryl Smith
If you believe you have late blight on either tomato or potato, you may submit a sample free of charge. Write "late blight confirmation" on the top of the submittal form.
Educational Resources:
- Late Blight: A Community Disease - prevention techniques and contacts flier.
- Late Blight: Prevention, Identification and Management - a slide show
- 2011 Potato Fungicides
- 2011 Tomato Fungicides
- Keeping Late blight in Your Rearview Mirror - commercial tomato grower version.
- Keeping Late blight in Your Rearview Mirror - commercial potato grower version.
- Keeping Late blight in Your Rearview Mirror - home gardener version
Visit The UNH Plant Diagnostic Lab
Return to the Cooperative Extension Agriculture page
