Plant experts warn of late blight

Print More

(Host) Plant experts are warning farmers and backyard gardeners to guard against a fungus that has the potential to wipe out tomato and potato crops across the region.

The disease is known as "late blight," and it’s what led to the Irish potato famine at the middle of the 19th century.

VPR’s Ross Sneyd has more.

(Sneyd) Paul Mazza pages through a thick book put out by New England university extension services each year for professional growers.

(Mazza) "There it goes. Outdoor tomatoes. …. Control. … We spray Quadrus, Bravo …"

(Sneyd) These are some of the things that a big commercial grower like Paul Mazza’s Fruits and Vegetables can spray on tomato plants.

By applying a fungicide, Mazza can protect his six acres of tomatoes from becoming infested with fungus that would kill the plants – and protect any profit they might produce.

(Mazza) "Instead of going every seven to 10 days, you’re going every five to seven days. It’s the same thing. The homeowner probably can’t do as well as us. If they put straw down or plastic down, that’ll help because it comes from the ground."

(Sneyd) And if he doesn’t spray?

(Mazza) "The plant turns yellow and dies. And you get spotting of your fruit and it all rots."

(Sneyd) Late blight inoculum is the culprit here. New England doesn’t usually see a widespread infestation, and certainly not at this time of year. When it does show up, the fungus thrives in wet weather.

Extension agents say infected plants were sold by a wholesaler from the South to big garden centers. Homeowners and backyard gardeners bought the seedlings and the fungus could spread on the wind in a broad swath of states and provinces from the Great Lakes to Maine.

(Grubinger) "The red lights are flashing."

(Sneyd) Vern Grubinger is the berry and vegetable specialist at the University of Vermont Extension Service.

He says late blight wiped out potatoes in Ireland in the 1840s and ‘50s, and thousands starved. We don’t rely on a single crop like that, so there’s no concern about starvation.

Commercial growers can spray and that’s usually pretty effective in controlling the problem.

Farmers who don’t want to spray, or people with smaller gardens, could be wiped out.

Grubinger says the only solution is to take out infected plants and put them in the garbage – not on the compost pile.

(Grubinger) "One could try to immediately remove those plants and put them in plastic bags and get them out of there. Again, if things were getting dryer. But as long as it’s wet, there aren’t a lot of options."

(Sneyd) Grubinger says gardeners should inspect their tomato patches for white fungal growth, as well as rot that appears on leaves. He says to remove the plants as soon as any signs of late blight show up.

For VPR News, I’m Ross Sneyd.

Comments are closed.