Tomato blight is back in North America

The tell-tale lesions first found on tomato plants at a western Massachusetts farm last week mean bad news. The tomato blight is back.

The fungus – the same one that caused the 19th century Irish potato famine - attacked last year’s tomato crop throughout the northeast, causing millions of dollars in damage to commercial growers and anguish to backyard gardeners. Other outbreaks this year have been reported in Maryland, Pennsylvania, and Canada. According to the University of Massachusetts Cooperative Extension Service, the fungus was brought to New England on plants that had been brought from the south and sold through major retail outlets. The cool, wet weather of last summer allowed the fungus to thrive. This summer’s weather in the region has been different – warmer and drier, and as recently as the first week of July, there was no indication that the fungus had returned. Now that has all changed. “Unfortunately, I think it’s a matter of time before it’s widespread,” said Meg McGrath, professor of plant pathology at Cornell University. “Hopefully people will be more knowledgeable of the disease this year realizing it’s a community disease.” Because the fungus spores become wind-borne, the disease spreads both quickly from plant to plant, and potentially over a wide area. There are some chemical treatments available, but organic growers shy away from these. The most effective way to halt the spread of the blight is to uproot and dispose of any infected plants.