Given the wet weather this spring, vegetable growers are concerned with an early arrival of late blight, as well as other diseases of horticultural plants. Late blight, caused by the fungus-like pathogen, Phytopthora infestans, can spread quickly and decimate entire crops.
Ann Hazelrigg, director of the UVM Plant Diagnotic Clinic, says that thus far this season there has not yet been an incidence of late blight in Vermont, although there there have been limited occurrences in Maine and Connecticut.
Hazelrigg urges vegetable growers to re-familiarize themselves with what late blight and other plant diseases look like. One option is to view the recording of the New Farmer Project’s “Introduction to Plant Disease and Management Strategies Webinar.” A good source of photos of late blight infection is at the Cornell University Long Island Horticultural Research and Extension Center at
“The best thing to do is [for people to] scout their gardens and send in samples if they suspect the disease,” Hazelrigg advises. “Gardeners should also scout and destroy any volunteer potato plants since this is the one place the disease could overwinter and be reintroduced.”
Commercial gardeners who suspect late blight may contact the UVM Plant Diagnostic Clinic at (802) 656-0493 or firstname.lastname@example.org. Guidelines for getting a sample analyzed are available at: http://www.uvm.edu/pss/pd/pdc/?Page=services.html
Home gardeners who suspect late blight should send a sample to the Master Gardener Helpline. Be sure to include an entire leaflet of the plant (back to the main stem) in a plastic bag with no moist paper towels.
“I would hate to recommend spraying preventatively at this point since the disease has not been found in the state,” Hazelrigg says. If the disease is found, “growers can apply copper fungicides or conventional fungicides on a weekly basis to try to stay ahead of the disease or just destroy their plants immediately if they do not want to spend time applying pesticides.”
Hazelrigg, the UVM Extension Master Gardener Program and UVM Vegetable and Berry Specialist Vern Grubinger will provide updates via list servs and news letters as the season progresses.