Late blight fungus destroying tomato crops

PINE ISLAND - The fifth annual Heirloom Tomato and Music Festival is scheduled to be held at the W. Rogowski Farm, 327 Glenwood Road in Pine Island on Sunday, Aug. 23, from 11 a.m. to 5 p.m. “But we may have to have the tomato festival without the tomatoes,” said farm owner Cheryl Rogowski. Black Dirt area farmers and local gardeners are currently facing a serious threat from a highly contagious fungus that destroys tomato plants and which has spread to most states in the Northeast and the mid-Atlantic. A strain of this same fungus was actually responsible for the deadly Irish potato famine in the mid-1800s. Millions of people in Ireland starved or were forced to emigrate when entire potato crops rotted in the field or in storage because of infection by the fungus known to scientists as Phytophthora infestans. However Maire Ullrich, vegetable crop resources educator at the Cornell Cooperative Extension of Orange County, believes that although this particular strain can infect potatoes, it is more likely to attack tomatoes. She added that there are chemical options for farmers or gardeners who wish to take that route to fight the disease. Otherwise, the infected plants should be destroyed. “We had a perfect storm for late blight development this year,” explained Rogowski, “a combination of very wet and cool weather. Remember there were 28 days of rain in June and not many dry days after that.” And Rogowski also cautioned that because the spores of the fungus are often present in the soil, the blight could return next year. She warned that anyone destroying plants should never use them for mulch and should place them in plastic bags before disposal. “One reason for this,” she said, “is that the spores are easily carried with the wind and can infect other plants now or later.” Warwick Town Supervisor Michael Sweeton reported that the blight has been especially tragic for local growers. “We were very hard hit,” he said, “and I expect this will be reflected by higher prices in the market.” Meanwhile, the fifth annual Heirloom Tomato and Music Festival, with or without tomatoes, will be held rain or shine. The event will still feature live music, pony rides, culinary displays, food and refreshments and much more. Discount tickets are available online. For information call 258-4574 or visit www.rogowskifarm.com Late blight Fungus What to look for: The symptoms that develop on tomato leaves, stems and fruit are quite dramatic, and are very obvious to the naked eye. The leaf lesions are water-soaked, varying in size from a nickel up to a quarter. They are water-soaked when the foliage has been exposed to watering or heavy overnight dews. When these lesions dry out quickly, they may appear lime-green in colored or even become beige. The edge of the water-soaked lesion, on either the top or bottom leaf surface, will be covered with white fungal growth that contains the spore inoculum. Warnings: Spores are easily blown to surrounding areas and infect plants and even some weed species in the family Solanaceae (the black nightshade family). Brown to almost black lesions develop on infected stems, and the same lesions will develop on infected fruit, either directly on the plant, or a few days after when they are sitting on a kitchen counter. It is not dangerous to humans, most of the fruit could be used if the affected area is removed. Inspect your tomato plants on a daily basis. If symptoms are already appearing on plants in your garden, these plants should be removed and put in a plastic bag for disposal. Do not put the removed plants in a compost pile as spores can still spread from the debris. Treatments: Commercial growers have a number of fungicides that if applied early and often, can reduce the spread of Late Blight. They would choose not to spray if they could, but this destructive disease does not give them any other option. Homeowners do have a few products that are registered for use. The most effective ones have the common name of chlorothalonil, which will be on the label. These products are only effective if used before the disease appears and should be reapplied every 5-7 days if cool, wet weather persists. Chlorothalonil is a protectant fungicide, with no systemic movement in the plant, so thorough coverage is necessary. Copper applications are not as effective as chlorothalonil. Diagnostic services: For those homeowners interested in getting diagnostic testing for late blight on tomato or other diseases on vegetables in their garden, contact your state university’s plant diagnostic lab service. It is critical to get potential Late Blight samples to the diagnostic clinic as quickly as possible. New York State residents can submit samples to Cornell Plant Disease Diagnostic Clinic at: http://plantclinic.cornell.edu/Sample%20Type%20Pages/late_blight.htm Sources: Cornell and Rutgers Universities