By DOUG GRAVES
Ohio Correspondent

COLUMBUS, Ohio — Wet, cool weather conditions this past spring played havoc with Ohio farmers’ planting schedule. Now there is another worry on the minds of many of these same growers – blight.

According to Sally Miller, a plant pathologist and vegetable crops specialist with the Ohio Agricultural Research and Development Center, the late blight is a potentially “devastating disease of tomato and potato plants and has been found in Ohio and may threaten home gardens and commercial operations alike.”

“Recent weather conditions will create a favorable environment for the spread of the fungal pathogen that causes this disease,” Miller said.

Responsible for the Irish potato famine of the 1840s, late blight has caused widespread crop damage across the U.S. and Canada since 1990. If left unmanaged, this disease (which is transmitted through spores) can result in complete destruction of tomato or potato crops.

“I wouldn’t say we’re heading towards a similar potato famine, nor would I say we’re clear of any such danger,” Miller warns.

“Fortunately farmers see and recognize the blight and at least know how to deal with it. But the home gardener and other small-scale growers may not recognize it and may not have the fungicide they need to deal with it. I’m a bit concerned with the organic farmers who don’t use any fungicide on their crops.”

Ohio is one of the country’s top tomato growers, with annual production valued at more than $130 million for both fresh and processing tomatoes. Ohio also produces more than 100 million pounds of potatoes annually.

According to Miller, first accounts of early blight in the U.S. was discovered earlier this month in the Northeast, beginning in New York and spreading into Virginia and Pennsylvania.

“In Ohio, late blight was confirmed in a non-commercial tomato sample on June 25,” Miller said. “Because infested tomato plants were traced to a garden center chain that has numerous stores across Ohio and the country, diseased plants may have already turned up on people’s vegetable gardens.”

Another blight, basil downy mildew, is also affecting plants in the northeast. The spores of both are carried by the wind and are enhanced with wet, cool conditions.

Late blight thrives under weather conditions that have hit most of Ohio the past two weeks, with nights in the 50s and days in the 70s. These temperatures, combined by rain, fog or heavy dew, make conditions ideal for blight. Under these conditions, lesions can appear on leaves within three to five days of infection, followed by white mold growth soon after. Spores formed on the mold are spread readily by irrigation, rain and equipment.

Miller says these spores “can also be easily dislodged by wind and rain and can be blown into neighboring fields within five to 10 miles or more, beginning another cycle of disease.”

“Now that the disease has showed up in Ohio, it is likely that is will affect a lot of home gardeners,” she said. “And if these home gardeners don’t control it well a lot of inoculum may be floating around if weather conditions favor the disease.

This inoculum can be a threat to commercial tomato and potato producers.”

For testing of suspected late blight-infested plant tissue, growers are asked to contact a local Ohio State University extension office, Miller’s lab at 330-263-3838 in Wooster or the C. Wayne Ellett Plant and Pest Diagnostic Clinic in Columbus at 614-292-5006.