Scary: Fungus Outbreak Threatens Northeast, Mid-Atlantic Tomato Crops
Per the New York Times, a fungus called the late blight (Phytophthora infestans) is threatening tomato crops and garden plants in the Northeast and Mid-Atlantic.
The spores of the fungus ... are often present in the soil, and small outbreaks are not uncommon in August and September. But the cool, wet weather in June and the aggressively infectious nature of the pathogen have combined to produce what Martin A. Draper, a senior plant pathologist at the United States Department of Agriculture, described as an “explosive” rate of infection.
The article says that William Fry, a plant pathology professor at Cornell, has been genetically tracking the fungus and says its spread is due in part to "hundreds of thousands" of plants bought at Walmarts, Kmarts, Home Depots, and Lowe's—all supplied with seedlings by Bonnie Plants. Bonnie Plants has since recalled remaining seedlings. [What to look for, after the jump.]
What to Look For
Late blight lesions on tomato fruit. New York State Integrated Pest Management Program
A strain of the P. infestans fungus was responsible for the Ireland's Great Potato Famine starting in 1845. According to Cornell's Integrated Pest Management Program, tomato fruit affected with late blight "causes a firm, dark, greasy-looking lesion from which the fungal spore producing structures emerge under humid conditions."
On leaves and stems, look for:
Black lesions appear within 3 to 7 days of infection of leaves. Under humid conditions, delicate, whitish fungal spore producing structures are produced at the edge of the lesion, particularly on the underside of the leaf. Lesions turn brown when they dry up,and are often surrounded by a halo of gray-green tissue.
If your plants are affected, the Times article says, you should pull it from the ground, seal it in a plastic bag, and throw it in the trash. For the love of God, whatever you do, DON'T COMPOST IT!
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12 Comments:
We have been addressing people's concerns about this at our garden center in Ohio the past week or two. None has been found around here, but customers are confused. If you do think you have it, after looking at these pictures, seal it in a bag and take it to your local county extension office. Please do not take your samples anywhere unless they are sealed up! (Same goes for bug issues people! Please don't carry them unwrapped into a garden center full of healthy plants!) If it has not already been found in your area, it is probably a more common summer tomato fungus or insect problem, but better safe than sorry.
Cary at 1:44PM on 07/17/09
Perhaps a naive question... I understand that late blight is hugely destructive to crops, and therefore, if detected on a plant in a home garden, that plant should be sealed and discarded. But, assuming my tomato plant has been infected with late blight and I don't know it (is it just me, or is it very hard to distinguish between plain old brown spots and brown spots due to late blight in those photos?!), is it harmful to humans to ingest fruit that is infected?
jbrach at 2:01PM on 07/17/09
:( that's scary. I'll be on the look-out. Our tomato plants arent doing so great, but they certainly don't look like that.
Also, Go Big Red!
engmcmuffin at 2:02PM on 07/17/09
Ok, good to know it can't be composted and must be contained and removed. A few questions:
1) Can it be burned? Or does that just send the spores up into the air?
2) If detected early, and infected plants be removed to protect the others, or is that futile? Can individual branches and leaves be removed from a plant, or will the whole plant be affected regardless of trimming off the infected parts?
3) Can the plants be sprayed with an antifungal of some sort? Would a solution of vinegar and or alcohol work?
Any info would help.
simon at 2:04PM on 07/17/09
Err that should read "If detected early, can infected plants be removed to protect the others, or is that futile?"
simon at 2:16PM on 07/17/09
If you look at the photos in the link of my first reply, the spots and all of blight are pretty different from the typical brown spots you see on tomatoes. It starts with stem lesions, the white powder is on the bottom side of leaves, and often the spots and lesions don't affect the whole leaf (it may still be otherwise green).
If it is infected, I understand that the fruit is not toxic to humans; I wouldn't eat more of it, but I would not oworry too much if you ate some before finding the disease.
@simon: do not burn it! you are right, the spores can travel miles in the air which is what farmers are concerned about.
An affected plant will not recover, and treatment will not help unaffected portions of the plant. Un affected plants can be sprayed with a fungicide such as Fungonil or Daconil containing chlorothalonil to help prevent it spreading between plants, or if it has been found in your neighborhood. Unfortunately, it looks like most organic fungicdes like copper dust, don't do much.
Cary at 2:24PM on 07/17/09
Thank you Cary. I wonder if the Agway will have any fungicide left by the time I can get there or if there will have been a run on it...
simon at 2:30PM on 07/17/09
Am I the only one that noticed "Hairloom" in the top pic...?
Red line, points deducted. Heirloom is correct.
finewinendine at 3:19PM on 07/17/09
@finewinedine: I noticed it as I was selecting the photo. There were other prettier tomato photos I could have used, but I thought it was sort of quirky and fun—even though it is probably driving some folks batty.
Adam Kuban at 3:45PM on 07/17/09
This is a very scary example of how dangerous it is to have so little oversight, and talk-the-walk concern for food safety, in our food system today. I am comforted only by the fact that I get my fruit and veggies usually from local farmers, who are careful about everything they do.
MyPersonalFarmers at 4:11PM on 07/17/09
thank you so much for the link to see photo's of the blight.... i know it's a big deal here in the hudson valley -- now why the hell does walmart, kmart, home depot and lowes have to sell tomatoes? when and where does it stop??? when they undermine the entire food chain?
now i have to really go and check my tomato plants. this really sucks.
i think people should start boycotting these stores.....
pooch at 6:35PM on 07/17/09
I'm not sure if that's what killed my tomato plants or if it was some other bacteria, but I'll never buy tomato seedlings again. All of my Bonnie plants withered and died for no conceivable reason, and now I'm worried that my raised boxes could be permanently affected. Will be starting from seeds this time and hoping for the best. Ugh.
shandygirl at 11:42AM on 07/20/09