October 22, 2021

Fighting the blight

Spread of disease threatens potato, tomato crops

Photos by Joe McIntyre/staff photographer

Joan Franklin of Valley View Farms picks a potato bug off of a potato plant.

Just the threat of late blight, a disease that decimates potatoes and tomatoes seen this season in Onondaga County, has already interrupted business for Cortland farmers.

Allan Gandelman, owner of Main Street Farms, won’t ship tomatoes to SUNY Cortland this year because last year late blight destroyed about 70 percent of his crop.

As a result, he is growing potatoes and tomatoes inside greenhouses this year and doesn’t have the space to grow as many as the agreement with SUNY Cortland would require.

Gandelman has sold tomatoes to SUNY Cortland’s Auxiliary Services Corp. food service since 2015, he said, but this year he will just have to supply other vegetables, like beets and carrots.

“I shipped 30 percent of what I wanted to, it’s a huge issue,” Gandelman said of last year’s tomato crop. “Every year, it’s getting worse and worse.”

In the summer of 2015, Gandelman shipped 4,000 tomatoes, used to produce 250 gallons of tomato sauce for dining halls in a farm-to-table operation that continued over the years.

Until now.

Late blight, which causes brown or black lesions on the leaves and stems of the plants and results in the crops rotting, has been confirmed in Onondaga County, according to the state Department of Agriculture and Markets. The disease can spread quickly from field to field, over several miles and it thrives in humid, wet conditions.

Farmers, and even home gardeners, have been warned to be on the lookout for signs of it. Infected plants cannot be composted and if growers notice signs of the disease, they should contact their local Cornell Cooperative Extension office, says the state department of Agriculture and Markets.

Franklin stands in a 7-acre potato field Wednesday in Scott while talking about how to deal with blight.

Farmer Joan Franklin was selling rhubarb and strawberries Tuesday morning at the Cortland farmers market in Cortland and said news of late blight coming so early in the season surprised her.

She’ll be spraying her potato crop this year at Valley View Farms in Scott. It’s expensive, but not as expensive as losing the entire crop.

“We can’t afford to lose seven acres of potatoes,” she said. That happened once, years ago, Franklin said. It’s a mistake she won’t repeat.

Some basic information about late blight

What is it?
A plant disease that destroys the leaves, stems, fruits and tubers of potato and tomato plants.

When was it first discovered?
It was first found in the United States in the early 1840s, devastating crops across the Northeast. It was also responsible for the Irish potato famine in the mid-19th century.

What to look for?
Look for black or brown lesions on leaves and stems. Visible white spores appear in humid conditions.

How bad is it?
The disease thrives in humid conditions and can spread quickly from field to field and over several miles.

What should I do if I suspect late blight?
• If you’re a commercial vegetable grower, work with your local Cornell Cooperative Extension office or regional vegetable specialist to select an appropriate fungicide.
• Organic growers will want a copper-based fungicide product.
• Greenhouse growers can call the state Department of Agriculture and Markets Division of Plant Industry at 518-457-2087.
• Home gardeners can call the Cornell Cooperative Extension office at 607-391-2660.
• Do not compost any diseased plant material.

Source: NY Department of Agriculture and Markets

Heather Birdsall, a livestock specialist for Cornell Cooperative Extension of Cortland County, has been calling, but has found no reports of blight. Yet.

Gandelman said moving crops into the greenhouse works for him, because of the drip irrigation he uses means water doesn’t splash onto leaves, which can perpetuate the spread.

Other farmers have outdoor drip irrigation that can reduce the spread, but Main Street Farms doesn’t, he said.

He hopes that after a couple of years, if late blight peters out, he can go back to growing outside and shipping tomatoes to the college. But right now it’s just too risky, he said.

“It’s already June and if late blight comes on bad this summer, no one is going to get outdoor tomatoes, they will all be destroyed before August,” he said.