Late blight, also known as potato blight, is a mold which favors moist and cool environments and can seriously damage potato and tomato crops.

Carlberg Farm Produce on Peck Settlement Road in Jamestown grows potatoes and four varieties of tomatoes for its roadside stand, and has dealt with blight in the past.

“I got the alert through email from Cornell, which is nice, greatly appreciated because then you know it is in the area and to be on the lookout for it,” Ginny Carlberg said. “I know we have had it in past seasons, it does well on rainy humid weather and it can move in on storms. It is something that we have been on the lookout for. For us, we have had it before so we know what to look for. Pretty much your tomato plants die overnight.’

This season, Carlberg made a point of ordering seeds that are resistant to blight, and is also using an organic fungicide to stave off the disease.

Photo by Jay Young Ginny Carlberg checks tomato plants at Carlberg Farm Produce on Peck Settlement Road in Jamestown. Cornell Cooperative Extension issued a blight warning last week that can harm both tomatoes and potato crops.

“It is an all-natural organic product and if you spray that on the leaves pretty much weekly that will help too,” Carlberg said. “So far we haven’t gotten late blight, but we are keeping an eye on it. We are right in the middle of our tomato crop right now so, fingers crossed.”

Following the advice of CCE, Carlberg also mowed down the tops of potato plants as a precaution.

“What we did was mow down the tops, because once the late blight is around it gets on the leaves and then it will go down into the potatoes,” she said.

The disease begins with gray and brown spots on plants, which are often accompanied by white spores on the underside of leaves in wet conditions.

“Late blight is present in Chautauqua County and is expected it to be found fairly soon in Cattaraugus County and Pennsylvania,” said Elizabeth Buck, Cornell Extension vegetable specialist, via news release last week. “Given the current weather patterns, there is real risk that late blight has already travelled on the storm fronts to new places. Now is the time to be very on top of your tomato and potato crop health – scout your fields twice weekly and start spraying.”

Laurie Farms in Portland has tended potato and tomato crops in recent years, but has not had any blight issues.

“We do (grow them) but we do not grow them for sale anymore, the tomatoes and the potatoes, but we still grow them for family use,” owner Bruce Laurie said. “I’ve known some friends that have had some experience with it, but us personally, haven’t had any experience with it. But of course I do spray my potatoes and tomatoes. I don’t remember the last time that I heard about it from Cornell, I read about it online at their site.”

Laurie also said that he chooses to grow plants that offer some natural resistance to blight, and mentioned that some heirloom varieties can have more problems.

“A lot of times they are quite susceptible to these diseases, and there is a reason to hybridize them to get away from that,” Laurie said.

CCE recommends weekly application of hlorothalonil, which goes by product names like Bravo, and Echo, to help prevent blight infection.

Anyone who suspects blight infection is asked to call CCE Executive Director Emily Reynolds at 664-9502 ext. 201 in order to help track the disease.