June 23, 2010
Bad news for vegetable gardeners and farmers. Late blight, a plant disease which spread rapidly throughout the Northeast last year and destroyed tomato and potato plants by the thousands, has been confirmed again this year in Connecticut.
Sharon M. Douglas, head of the Department of Plant Pathology and Ecology at the Connecticut Agricultural Experiment Station in New Haven, said the blight was confirmed in recent days on tomato plants in New Haven County.
Late blight damage to a tomato
Gardeners tending plots in the Kolp Community Garden in Farmington also suspected the blight had reappeared, but a station scientist checked today and found no evidence of the pathogen.
Late blight is caused by a fungus-like organism that appears as olive-brown to black blotches on leaves and stems. Tomatoes develop brown or black lesions. Entire fields of tomatoes or potatoes can be rapidly infected and killed.
Because the potential for a widespread outbreak in Connecticut is again possible, Douglas said “all tomato and potato plants should be considered at risk.”
Farmers and gardeners must be aggressive in dealing with the blight, she said. Tomato and potato plants should be inspected often. Any plants with symptoms should be immediately removed and placed in a plastic bag to avoid spreading the blight. Affected plants should never be composted.
Avoid overhead watering, which can spread the blight, and stake and mulch plants if possible. Fungicide sprays also may be necessary, she said. Organic fungicides such as copper are one option.
Douglas said the massive outbreak last year was initiated by the sale of infected tomato transplants from chain stores throughout the Northeast. Once planted, a long period of wet, cool weather from May into July provided ideal conditions for the blight to flourish.
Because some infested plant material could overwinter, the potential for the disease to affect plants again this year was considered high.
Late blight is infamous as the pathogen associated with the Irish potato famine of the 19th Century.
An excellent fact sheet on late blight is available from the Connecticut Agricultural Experiment Station.