How to fix contaminated soil?

[Bert Hyman]

My wife and I are absolutely not knowledgeable gardeners; our back yard is planted with perennials and shrubs selected mainly for appearance, hardiness and whim (I got three gas plants, based solely on their name), and we manage to keep things alive and pruned to our satisfaction.

A few years ago, we set aside the one small sunny spot for growing tomatoes and basil. Each year we've tilled the area by hand, worked in some manure-based soil amendment, planted a few plants we picked up at the garden center and were happy with the result.

This year, the tomatoes died, and the basil is stunted.

My suspicion, and the consensus at my wife's office, is that we introduced some sort of blight, either from the purchased plants or the soil amendment.

What can we do to this plot of death so that we might get something to grow next year? Is there any quick fix for this year? Our growing season is terribly short here.

[Billy]

I'm guessing that your plot is screwed for 3 to 5 years. In any event, the only thing you can do with confidence is to lay down a sheet of fairly thick vinyl and put a raised garden on the site with fresh soil. Do you have any pictures of the tomatoes and basil, or can you describe how they looked? Did your tomatoes look like

or

Are your stunted basil forming black lesions on their stems?

[Bert Hyman]

That's a good idea, even after things might have healed; that would give us a more controlled environment.

They look almost exactly like Fig 1. of the Iowa State publication, illustrating "Septoria leaf spot."

No. The basil doesn't actually look diseased; it's simply not developing. So far as I can tell, the plants look exactly like they did when we bought them a few weeks ago.

Well, it's still early enough in the year that we might be able to get something going in containers or elsewhere in the yard. A summer without tomatoes & basil is not something I want to look forward to.

[Bert Hyman]

You raise an important point. My wife reports that she uses an 11-15-11 granular fertilizer. I can't say exactly how much, or exactly how it's used, since my involvement in the project is mainly digging and hauling, but I trust that she's using it as directed.

Thanks for the links.

The U of Mn's extension service has a soil testing service, and our county has an open plant diagnostic clinic every week that we can use if we can't arrive at a conclusion ourselves.

[balvenieman]

Don't be too quick to conclude your veggies to be diseased. You made no mention of what other veggies might be growing in that plot and how they are doing. If you've raised the same few kinds of plants in the same small area for a few years, your plants may be suffering a nutrient deficiency. Unless you have made it so, your "manure-based soil amendment" does not even come close to providing the balance of nutrients needed. The "Law of Minimum" (Justus von Liebig) maintains that yield is proportional to the amount of the most limiting growth resource. Even though the Big Three and soil pH may easily be tested with handy-homeowner devices, it can be very difficult to diagnose nutrient deficiencies. You can get NPK testing kits at most garden centers but, IME, you'll get more for you money in a pH testing kit from an aquarium center. If you have the wherewithal, by all means, start some new container plants in new soil but you might be doing yourself a favor to take an evening and really study any of the links below that interest you. Much of the information is redundant and repetitive but studying the images may help you identify an easily-cured deficiency that responds positively to the "three-day" test (in general, that's how long you should wait for a visible response to fast-release corrections).

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[Una]

The basil not growing sounds like nights have been too cold. Did you have a late frost overnight? Did the tomato leaves turn darker green and limp, kind of like they were stir fried or blanched in hot water?

Una

[Bert Hyman]

We've been having unseasonably warm weather lately, which is why the tomatoes went in a couple of weeks earlier than normal; it hasn't been below 50 since they went in.

Actually, they sometimes look a bit like that during the heat of the day, but perk up in the evening, looking their best in the morning.

Until they curled up and died, that is.

[Billy]

The pictures in seem to be a little better. It looks like you have an experiment to do, if you're up to it. Plant one more tomato where you had your problem and follow the cultivating practices outlined in the article.

organic or not, have shown limited results with Septoria leaf spot: ? Copper and sulfur are fungicides approved by the National Organic Program (NOP) Standards. Application of copper is a routine disease control practice in organic tomato production in the eastern United States. Copper functions both as a fungicide and bactericide and is labeled (under the NOP) for anthracnose, bacterial speck, bacterial spot, early and late blight, gray leaf mold, and septoria leaf spot. Commercial products like Kocide 101 are used in both conventional and organic tomato production for the control of Septoria leaf spot, bacterial spot, bacterial speck, anthracnose, and early blight. Applications are made on a 7-10 day schedule and the result may be 8-12 sprays per growing season. See the resource Eggplant, Pepper, and Tomato XXIV; Septoria Leaf Spot by Howard Schwartz and David H. Gent of High Plains IPM for information on applying specific copper fungicidal controls. Note that the pesticides listed in this publication are not all organic. Only some of the copper fungicides are permissible.

[zxcvbob]

How about fumigating with trichloronitromethane? It's pretty nasty, but it breaks down and/or dissipates rapidly. It also goes by the name chloropicrin.

Bob

[General Schvantzkoph]

I'm spraying with copper fungicide this year to prevent early and late blight, you might want to give it a try.

[General Schvantzkoph]

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Chloropicrin was used by the Germans in WW I, I sure as hell don't want to treat my backyard like Ypres.

[balvenieman]

Uhoh. I don't want to ignore my own advice and jump to conclusions but that's a classic symptom of nematode infestation. They colonize the plants' roots and block the vascular system, stunting growth and causing the daily wilt-down that you notice. Curling up and dying is extreme but is most likely during hot weather. Look for irregularly-shaped nodules on the roots near their bases or irregular swelling at the root crown and stunted appearing roots. The nodules in no way resemble the spherical nodules you see on nitrogen-fixers. The condition is pretty easy to spot because the roots just won't look "right".

[David Hare-Scott]

I think Balvenieman makes a good point, the other guys are assuming your conclusion about contamination and going for the nukes, even if reluctantly. Unless I saw obvious signs of pathogens I would not jump to that conclusion.

David

[FarmI]

The first thing I'd do would be to find another spot and cultivate that. There's only be one mild mention of the problems of trying to grow the same plants over and over again in the one plot of soil. Read up about crop rotation and why that is important (and supposedly even more so if you're not an organic gardener) and then start another bed in another place and continue to do that every couple of years before you go back to the first spot again.

[Billy]

Just no best place to start in describing this as a horrible idea. Chloropicrin is related to the WWI gas, phosgene.

works on people by destroying the alveoli in the lungs.

To risk this to treat Septoria leaf spot in the face of the National Sustainable Agriculture Information Service saying "fungicides, organic or not, have shown limited results with Septoria leaf spot.", is mind boggling.

I'd be more inclined to aviod the risks, especially since a raised garden can be put in place quickly, and to plant one tomato (to verify that it is a pathogen) and mustard in the suspected area.

Mid-Columbia growers add hot mustard to fields

Using mustard as a so-called green manure crop in the Mid-Columbia dates back more than a decade. Besides killing nematodes, chopped and tilled mustard also fights soil-born such as verticillium wilt.

If the test tomato meets the same fate, follow suggestions by

call a local Ag extension.

[zxcvbob]

I mentioned it because I knew it would get a reaction. ;-) But it's actually one of the safer soil fumigants, used to kill fungi and nematodes. It's a restricted use pesticide with a warning level of "DANGER", so it would have to be applied by a professional (so there wouldn't be an exposure risk to the OP) And it breaks down rapidly, doesn't leave a toxic residue in the soil and if used properly it won't contaminate the ground water or runoff.

Crop rotation is probably a better solution, but not as dramatic.

Bob

[phorbin]

Which is very good reason for not mentioning it.

[sherwin dubren]

Bert,

You might try covering the area with dark plastic sheets. The effect of the sun's heating and the lack of light might kill whatever is in your soil. The safest thing is to remove the top layer of soil and replace it with something suitable. Is anything else, like weeds, growing there now? Nothing growing is a more serious problem. Did you spray any weed killing chemicals there? A neighbor of mine accidentally sprayed what he thought was a weed killer, but it turned out to be a total plant killer.

Sherwin