April 08, 2020

’98 potato crop faces increased blight threat

CARIBOU — The potential for late blight, a disease that can wipe out a potato field in days, is expected to be greater during the 1998 season as a result of the disease being found late last year, a potato researcher said Thursday.

To counter the threat, the state’s potato farmers need to be more vigilant in scouting their fields this year in an effort to find the disease early enough to apply fungicides.

“I don’t think late blight’s going away,” said Dr. Steve Johnson, a potato researcher with the University of Maine Cooperative Extension, during a talk at the annual Maine Potato Conference in Caribou.

Johnson said late blight showed up later in the growing season last year. With those potatoes now in storage — and some of which will be planted this year — the disease has the potential to show up earlier in the coming crop.

Late blight is a fungus that affects the potato plant’s ability to produce tubers. It also renders the potato defenseless against other diseases. Tubers with late blight also deteriorate while in storage.

The disease, which is spread by spores, was the cause of the Irish potato famine 150 years ago, which resulted in a mass migration to the United States. Aroostook County farmers have faced problems with the fungus throughout the decade.

About 250 potato growers from Maine and New Brunswick attended the 13th annual conference, sponsored the cooperative extension and the Central Aroostook Young Farmers Association.

Besides two days of information on various potato diseases and production and marketing techniques, dozens of industry vendors set up booths for potato growers to browse through during breaks.

During his presentation, Johnson said the cooperative extension plans this year to continue and expand its system of forecasting when late blight could occur. Automated weather stations, which can measure humidity and other factors encouraging late blight, are scattered in potato fields throughout Aroostook County.

Information gathered from those stations are analyzed and recommendations for treating late blight are put on a recorded telephone message to help farmers decide when it’s time to apply the fungicide. The message is available through a toll-free telephone number. Last year, the service received 1,300 calls, Johnson said.

Use of the forecasting information also may help farmers use fungicides more economically. Last year, the information disseminated on the forecasting system saved County growers three to four applications.

While the chemicals are needed to keep the disease in check, combating the disease is expensive. According to Johnson, one application of fungicide can cost Aroostook County growers a total of $1 million, based on the current amount of acreage and the cost of spray materials.

Total costs per growing season to fight late blight can climb to $15 million, according to pesticide company representatives at the conference.

“It’s also 100,000 pounds of [pesticide] material that doesn’t go in the ground,” Johnson said, referring to the environmental concerns of pesticide usage.

Another UM Cooperative Extension researcher, Dr. Dave Lambert, advised growers that seed potatoes harboring the disease need to be treated with fungicide before planting. Through his research, Lambert determined that the potentially infested seed should be planted as soon as possible after cutting. Each seed tuber is cut into sections before planting.

Other topics discussed during the two-day program were the potential for soybean cultivation in the County; choosing the right spray equipment and other pest control management techniques; and irrigation techniques.

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