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BREAKING: Irish potato famine "late blight" spores could destroy your garden, propagated by "big box" stores

First, some detail for the gardeners, in case you want to go right out and deal with this: Late blight is the fungus that caused the Irish potato famine. Here's a slide show that shows what to look for on tomatoes. The fucking rain (at least on the East Coast) has created moist and cool conditions that are ideal for its spread. The fungus spreads through the air, goes after both tomatoes, potatoes (and peppers and eggplants), and can take down a garden in 3-5 days. Whether or not it originated in the big box stores, they are a likely source of infection now. Finally, copper fungicides work (that's been my experience with mildew on winter squash, though I combine that with milk spray) though wear a moon suit when you use the stuff. The Oregon Extension Service recommends cleaning your tools with bleach. Penn State master gardeners say don't rip out plants, because that spreads the spores, and recommend alternative procedures. If anybody has better information, please share it!

* * *

Yikes. "Spores in the air." Sounds like a horror film! And just like a hospital with superbugs can infect all its patients, an infected Big Box store could blight an entire bio-region, and destroy your garden, even if you didn't personally buy an infected plant. Isn't it great how, even if you're working to become self-sustaining and grow at least some of your own food, the corporations can still fuck you up? Reuters:

Late blight, which caused the Irish Potato Famine of the 1840s and 1850s, is killing potato and tomato plants in home gardens from Maine to Ohio and threatening commercial and organic farms, U.S. plant scientists said on Friday.
"Late blight has never occurred this early and this widespread in the United States," said Meg McGrath, a plant pathologist at Cornell University's extension center* in Riverhead, New York.

She said the fungal disease, spread by spores carried in the air, has made its way into the garden centers of large retail chains in the Northeastern United States.

"Wal-mart, Home Depot, Sears, Kmart and Lowe's are some of the stores the plants have been seen in," McGrath said in a telephone interview. "This pathogen can move great distances in the air. It often does little jumps, but it can make some big leaps."

The moral here, for next time, is buy local, and drive the Big Box "Garden Centers" out of business.

The disease, known officially as Phytophthora infestans, causes large mold-ringed olive-green or brown spots on plant leaves, blackened stems, and can quickly wipe out weeks of tender care in a home garden.

This year's cool, wet weather created perfect conditions for the disease.

Like fucking the solid month of rain we've had here in Zone 5b, and all over the east coast.

"Hopefully, it will turn sunny," McGrath said. "If we get into our real summer hot dry weather, this disease is going to slow way down."

Pray for sun -- though I just looked at, which has been bad in detail, but good on the percentages -- and two out of the next 10 days are cloudy.

If you're a grower, you probably know this already, but if you're a gardener, go out there and deal with this today:

And while some sprays have also been approved for organic use, many organic farmers do not use them, making it much harder to control.

"If they are not on top of this right from the very beginning, it can go very fast," she said.

In my experience with mildew on squash, copper prevents infection. WARNING: Copper is nasty, nasty stuff -- "acutely toxic," so read the label and do what it says. I used dust, but it's looking like spray is easier. And be sure to coat the undersides of the leaves:

Copper fungicides can be highly effective if applied prophylactically (before infection) and with complete coverage of all plant foliar surfaces, including the undersides of leaves where the pathogen typically sporulates.

Copper fungicides are protectants, so they MUST be applied to the foliage before infection. The copper ion is absorbed by the germinating spore, and the copper denatures spore proteins. Once infection has occurred, copper has no effect on disease progress in the plant.

So, after I press Submit, I'm going to go out and try to prevent this. But first, the media critique. Let's see who mentions the big box stores, and what they say!

1. Izvestia: No current story, despite all those trendy stories we've been reading about urban gardening.

2. Pravda. No mention of Big Box stores.

3. Reuters (quoting plant pathologist McGrath):

"Wal-mart, Home Depot, Sears, Kmart and Lowe's are some of the stores the plants have been seen in," McGrath said in a telephone interview.

4. Newsday (Long Island):

.... has been found at the retail level on Bonnie Plants tomatoes, which are sold at The Home Depot, Kmart, Wal-Mart and Lowe's stores on Long Island


5. Houston Chronicle (framing it as "Is East Coast Tomato Blight Spreading?"):

Tomato plants have been removed from Home Depot, Wal-Mart, Lowe's and Kmart stores in all six New England states, plus New York. Late blight also has been identified in all other East Coast states except Georgia, as well as Alabama, West Virginia and Ohio

6. Canton, NJ Daily Record:

Vineland homeowner who planted 100 infected tomato plants saw last week that they were dying and alerted agricultural officials, who had the plants destroyed. The supplier, Bonnie Plants, a plant wholesaler based in Alabama that distributes plants to Wal-Mart, Lowe's, Kmart and The Home Depot, recalled about $1 million worth of possibly infected tomato plants from stores in New Jersey and nearby states.

7. Maine Public Broadcasting Network:

Dill says home gardeners should also inspect their plants and remove the infected ones. "Take out the disease plants and then take out a little section around it and destroy it. Do not compost those plants because composting won't necessarily kill it in time and it can continue to spread."

[Jim Dill of the Maine Cooperative Extension Service ] says states from Pennsylvania to Maine have issued warnings about late blight. The problem has been compounded by the widespread sale of infected tomato seedlings sold by Alabama-based Bonnie Plants at Walmart, Home Depot, Kmart, Lowes and other garden stores. Bonnie's general manager Dennis Thomas says his company is pulling its remaining product from store shelves.

8. Irish Central:

The big box stores Wal-Mart, Home Depot KMart and Lowes have issued a $1 million recall of possibly infected tomato plants and experts believe the current outbtreak could have originated there.

Funny how as you go move along the media food chain from top to bottom, the assignment of responsibility, and the use of the active voice, increases, eh? (Also, these stories are mostly written by local reporters, who called and interviewed local gardeners, growers, and the agricultural extension service. Nothing ripped from the wires, and no Rolodex journalism here! One might even imagine the top-of-the-food-chain guys as, well, being infected with some sort of blight...)

NOTE * If you want to give your anti-gummint friends an example of good things the government does, The Agricultural Extension Services are a fine example. (As is the system of land-grant colleges generally, I think).

UPDATE Off to the local hardware store!

UPDATE Well, after churning about on Zone 5b's hideous public transportation for the afternoon, I find there's no 100% copper (powder form) to be had anywhere in the area, and everybody sells more or less the same thing, so I settle for the 7%. I'd be annoyed with Wal-Mart if they simultaneously endangered my garden with spores and sold me the product to protect it (that would be Monsanto's business model), but I'm almost as annoyed that they endangered my garden and didn't sell me the product to protect it. Market failure, and on the local level, too, since the local hardware store was already out of the moon-suit stuff. Damn.

UPDATE At least I can protect the potatoes by surrounding them with garbage cans or 5-gallon pails with the bottoms cut off, and then fillling them up with dirt to cover the flowers. There's that.

UPDATE Done. And tomatoes covered with Rotenone with 7% copper. Ugly, but not petroleum-based.

No votes yet


connecticut man1's picture
Submitted by connecticut man1 on

ripe tomatoes had big brown spots and I tossed them. My peppers stopped as runts and are barely alive. My eggplants and squashes were planted late so they are still small BUT I probably gave them all Blight with my shovels and rakes and other implements of destruction.

I saw this story yesterday and was going to ask you all if you had any remedies for it. Copper fungicides, eh?

Crap... I was just reading your link and I may need to destroy nearly all of my plantings. WTF???

Submitted by lambert on

But I'd go do some research on prevention immediately.

I didn't have time to do more research on organic methods -- copper, though totally nasty, at least isn't petroleum based. Maybe there are other methods out there that I didn't find.

Submitted by gob on

is a product I found through your link to the Penn State blog (described at this page at the National Sustainable Agriculture Information Service).

It's a preparation of a bacterium, B. subtilis, is approved for organic farming, and is recommended as a broad-spectrum preventive for fungal diseases including late blight. I don't have any disease indications right now (we've had wet weather, but not disastrously so). But I have two Home Despot tomato plants along with my home-started seedlings, so I've ordered some as a preventive.

Copper looks scary.

Many many thanks for the repeated warnings!

TreeHugger's picture
Submitted by TreeHugger on

but we've had lots of sun and not much rain in western Oregon this year, plus I plant heirloom stuff from a rural nursery.

FWIW I have had good success with a general fungicide, Neem Oil, which I've bought in concentrate and mix up in a spray bottle for use on ornamentals such as domesticated lupine that are prone to powdery mildew, black spot, etc. It's relatively safe and 'natural'. It interrupts the spreading mechanism of the fungi, which might be the same way the blight spreads. Sorry I don't have time to research this any more for you to see if it could be used on veggies (foilage) but I am off to my class (making fused glass GARDEN ornaments).

Sincere condolences on the weather... the deer...and other instances of Mother Nature's way of paying us back for F^*king with her ...just your turn this year.

MsExPat's picture
Submitted by MsExPat on

It comes from India--from the neem tree--and its biggest use over there is in ayurvedic medicine, and hair oil.

I have a bottle and I use it on my scalp sometimes. Indian women swear to me that if I keep using it my hair will grow longer and thicker.

And I guess my scalp won't get potato blight, either!

viejolex's picture
Submitted by viejolex on

Too late for me in El Paso, Texas - I pulled up most of my extensive (about 30) plants for canning tomatos yesterday - after seeing your images, it occurred to me that I was looking at my plants - my peppers are shot, but my corn and watermelons are doing well - they seem not to be affected. Instead of starting seeds from scratch as iI normally do, I bought several six packs of 3-4" plants from Wal-Martl. They sure as hell are the culprits.

Although there is considerable doubt that I will be around for next year's garden, as I have congestive heart failure and the systems are clearly slowing down, any ideas what to do with the infected soil other than totally replace it?

Submitted by brucedixon on

I buy all my stuff from some north Georgia good ol' boys up the street. Don't think there are any big box plants in my garden at all this year unless they were grown from seed. The godly among us down here pray for rain, not more sun, and this is the first year we've got half enough.

Plenty of problems with cornworms and other unidentified pests though, including a nephew who couldn't be bothered telling some of my melons and squash from weeds.

I'm thinking of composting him. Not sure how vigorously the wife would object.

zuzu's picture
Submitted by zuzu on

How do you tell the difference between blight and just standard yellow, weak plants from a solid month of rain?

I have some moldy bits on the stems, the leaves have almost all shriveled, but somehow the fruit is still hanging on, and still has no blemish. I bought them from a local garden center with its own greenhouse, not a big box store.

Since the plants are pretty much toast, would I be better off just tossing them and trying again a bit later in the summer? Should I dump all the dirt from my windowboxes as well?

Submitted by lambert on

What you have sounds like "garden variety" [I'd laugh, except I'd cry] mildew, to me. So I wouldn't toss them -- get all the yield you can!

And I have to say that it feels weird to me to be given gardening tips -- up here in Zone 5b, it's a "hot bed" of gardeners, and I'm the least of them.

That said, I am an expert in one thing at least, and that's mildew! Mildew does get in the dirt. I don't know what your situation is, so I can't say whether you should dump all the dirt from your windowboxes; depends on how good the soil is otherwise, I would say. What I do know is that, since the mildew is in it, you're just going to lose the bottom leaves to splashes from the rain -- and that you should avoid splashing when watering. I just pick all my bottom leaves off, and the higher-up ones are always fine, both because they're higher and possibly because they are tougher.

zuzu's picture
Submitted by zuzu on

My basil plants are doing just fine, in the same boxes with the tomatoes.

I threw some pea gravel on top of the soil to keep down the splashing, since it tends to bounce into my windows and make the sills and screens muddy.

Submitted by lambert on


Starts out by saying that late blight doesn't infect the soil at all, but then goes on to say that there are interbred kinds that do. So...