Late blight, a fungal-like pathogen that affects potato and tomato crops, has been confirmed on Long Island for the sixth consecutive year.

The first confirmed infection is estimated to have taken hold on June 13 in a potato field in the Riverhead area, with three more occurrences in tomato fields in the same area, most recently on July 17, said Meg McGrath, Cornell University plant pathologist with the Long Island Horticultural Research and Extension Center, in Riverhead.

The disease in those fields "is fairly well contained," she said, thanks to the vigilance of farmers and their use of targeted fungicide, but it could also be present in other fields and area gardens.

Late blight is "a very destructive and very infectious disease," spread by infected tomatoes and potatoes or through spores blown by the wind, according to McGrath in "Late Blight: Frequently Asked Questions."

Entire crops can be wiped out by this disease, the same one that led to the Irish potato famine in the mid-1800s.

Easily discernible in grown produce, the disease is not usually associated with "human health concerns," said Sandra Menasha, vegetable and potato specialist with Cornell Cooperative Extension in Suffolk County.

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It's "fairly obvious to a consumer" with "big, greasy black and brown spots on tomatoes" and discoloration of potato skins, with a "mahogany-colored, grainy texture" inside.

Knowing the risk to their crops, farmers "are very much on top of it," McGrath said, but home gardeners are wise to become better educated. If their plants get infected, other gardens can be affected, as well as commercial growers and their livelihoods, she said.