By Kelly Johnson and Nicole Mulvaney

STAFF WRITERS

HOPEWELL TOWNSHIP — Organic farmer Jess Niederer is terrified of late blight, a destructive disease specific to tomatoes and potatoes that was recently discovered on five farms in the state. She knows the fast-spreading disease has the potential to wipe out her crop of tomatoes at Chickadee Creek Farms, and she also knows the first case of blight in New Jersey this year was discovered in Mercer County.

“Cherry tomatoes were my No. 2 seller last year,” Niederer said. Her crops were struck with the disease last year, but it was late enough in the season to spare her from losing a significant amount of money.

This season, the first case of late blight in the state was confirmed in Mercer on an organic farm in late June, said Meredith Melendez, agriculture coordinator for the Rutgers Cooperative Extension of Mercer County. Four other cases were confirmed on farms in Salem County this week, said Andy Wyenandt, a vegetable pathology specialist for the Rutgers Cooperative Extension.

Late blight usually makes its appearance between August and October, when the growing season is at its end, making this year’s early reports unusual — and worrying, Melendez said.

Late blight thrives in moist conditions and cooler temperatures, and completely destroys the affected plants within days, Melendez said. With the recent heavy rain in the state, the disease is manifesting much earlier than usual, she said. The sooner late blight appears in the growing season, the worse it can be.

“With all of this moisture, for growers, statewide diseases are coming on earlier than usual. It’s not going to be a normal year,” Melendez said.

Experts are anticipating a significant impact on the economy, as tomatoes are considered an important state commodity.

“We need five or six days of 90-degree weather to dry out these crops, because that will shut down the disease,” Wyenandt said. “That will benefit farmers the most.”

The disease, which was responsible for the Irish potato famine of the mid-1800s, creates fuzzy spores and dark lesions on leaves and stems of tomatoes and potatoes and quickly kills the entire plant. While the infected plant does not harm people if eaten, the rate of destruction remains a significant threat to farmers, Wyenandt said.

“This could really wipe out a tomato crop. You could have nothing one day and the next day start seeing symptoms,” Lawrence farmer Walter Bonczkiewicz said. Though he hasn’t seen symptoms of late blight on his crops at Village Farms this year, “once you get it, you’re done,” he said.

The spores have the potential to travel up to 30 miles by wind, rain or other disturbances, said Margaret McGrath, associate professor of plant pathology and plant-microbe biology at Cornell University.

Even backyard farmers can unwittingly aid the spread of the tomato blight.

“Home gardens are just as likely to spread disease to other farms,” Niederer said. “This pathogen is so fast-moving and travels on weather so easily.”

“The ideal thing is to rip the plant out and destroy it. There’s real potential to spread it from a home garden to a farm,” Melendez said.

Wyenandt said the culprit behind the spread of blight in the southern portion of New Jersey this year was likely the infection of a commercial potato field near Leipsic, Del. The infection discovered last month on the Mercer farm is believed to have been started by an infected plant from the previous year that remained in the field.

This year’s epidemic bears an eerie similarity to a problem with late blight in 2009, when a majority of the state’s tomato crops was wiped out. In that case, the epidemic also made its first appearance in June. According to a recent report by McGrath called “Late Blight: Recent Occurrences, Challenges and Future Outlook,” late blight occurrences in 2009 were “unprecedented” and had tremendous impacts on growers and gardeners.

To protect themselves, farmers should check their crops daily and use fungicides to prevent late blight, Wyenandt said. Organic growers can use liquid copper fungicides to suppress development, but it must be reapplied to every leaf surface each time it rains in order to be effective, he said. However, because the disease spreads so rapidly, by the time symptoms are first noticed it is almost impossible to save the crop, even with the most effective treatments, according to McGrath.

Because the disease resembles other fungi and mold, suspicious samples should be tested by experts upon initial findings due to its rapid progression. Growers in the state are encouraged to contact experts at their county’s agriculture agency if they suspect the disease, Melendez said. Samples can be dropped off and tested at her local office at 930 Spruce St. in Trenton, and results can be available immediately. Local growers with questions or concerns can call Melendez at (609) 989-6830.

Leaf samples may also be sent to Wyenandt or Bill Fry, professor of plant pathology at Cornell University, who will evaluate plant genetics to determine the disease strain, Melendez said.

“From a farming perspective, it is a community service to local farmers to not be a late blight source,” Niederer said. “If your crops are infected, rip out the plot.”

For more information about late blight, including history, facts and photos, visit www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm.

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