After likely staying alive through a mild winter and spring, late blight - the plant disease that caused the deadly Irish potato famine - has been found in area farms for a fourth consecutive summer.
"We're finding it in more counties every day," said Beth Gugino, assistant professor of plant pathology at Penn State University. "We're trying to get the word out that it's around."
Late blight affects potatoes and tomatoes, rotting them and making them appear dark and corky. Left unchecked, it can spread through entire crops when mild, humid weather gives it an opportunity to develop.
The disease, spread through contact and proximity by airborne micro-organisms, thrives when temperatures stay between 65 and 70 degrees.
It was spotted this month in Blair, Franklin and Mifflin counties, according to a Penn State news release.
While large farms and agribusinesses generally employ fungicides that prevent or kill late blight before it takes effect, small-scale farmers and gardeners are at particular risk, Gugino said.
"The people with the fewest tools to manage it are the home gardeners and the organic farmers," she said.
One farmer this season had to cut his entire crop early to stop the disease's spread, Gugino said - in essence, destroying the village in order to save it.
Jim Benshoff, whose New Germany farm includes roughly 18 acres of potatoes, said the mild winter might have left living, unfrozen potatoes in the ground, providing a host for blight until the crops regrew in the spring.
"A lot of gardeners - they wouldn't recognize it until it's too late," Benshoff said.
Large-scale farmers like Benshoff keep a close watch over their potatoes when the warning goes out; Benshoff said he's increased the frequency with which he sprays his crops to once a week. If weather becomes cooler and wetter, he said, he'll likely increase it further.
"You can't just go out and do it once, and forget about it for a week," Benshoff said.
While outbreaks in the last two years were manageable, a major attack in 2009 caused widespread economic damage, Gugino said. The 2009 outbreak began when infected tomato transplants were used in gardens, eventually allowing the blight to spread to commercial farms.
Since then, farmers have been more knowledgeable and more prepared for outbreaks, she said.
If late blight is detected - it's easily recognizable by brown spots on potatoes and tomatoes, and by white, fuzzy growth on leaves - farmers should immediately pull out the affected plants and keep them sealed in a plastic bag, Gugino said.
Because the spore that causes late blight is airborne and survives in a wide range of weather conditions, dying plants and potatoes left in the ground can still carry the disease.
While late blight-specific fungicides are most effective, organic farmers and gardeners can use copper-based products to stem late blight's spread, Gugino said.
In the end, though, weather will likely play the largest role in determining how far late blight expands this season.
"If it's hot and dry, it's going to stop things in their tracks," Gugino said.
"As soon as it gets cool and wet again, it's going to pick up again."
Mirror Staff Writer Ryan Brown is at 946-7457.