Monday, June 17, 2013

Persistent Herbicides, OR, Manure Isn't What it Used to Be

Pepper plant affected by persistent herbicide in Cobb County, GA. PHOTO/Amy W.
I have a friend who has been farming for a very long time, and his life experience has told him that Manure Is Good.

He has friends - owners of stables of horses - who offer to provide him with enormous amounts of composted manure, and he accepts.

Even though he has had trouble with manure before (a couple of years ago), he spread it on some of his planting beds again this year, and the tomato-family plants, not too surprisingly, have become twisty and weird.

The leaves from before the spreading of the compost look fine, but all the growth since the application looks pretty bizarre.

The North Carolina State Univ. publication about Herbicide Carryover explains that the chain of herbicide-treated hay to horse to compost needs to be very clear. Unfortunately, in the casual exchanges of small-plot farmers, the information chain can become a little vague. That can be a problem for garden-farmers who are hoping to produce healthful food from their land.

For any of us who have always thought that manure can be a great amendment to the soil for their vegetables, it is good to remember that times have changed, and that not all composted manures are what they used to be.


  1. Thanks for the link to the earlier post. I think this is happening to our garden this year. I think some of the clippings from my moms front yard, which she has a lawn service treat, have been used around the tomato plants. They look all pointy like those in your older post. One plant looks very sickly as well. I have tried to caution against using the front yard clippings as mulch, but it gets forgotten over time. Plus, it's my 17 yo son who does the mowing and, well, there's another layer of forgetting/not caring, etc. trying to get him to remember to dump the clippings at all is sometimes an issue.

    The real question is, what now? Obviously stop using those clippings on the garden. But will it help to try to gather up any clippings I can from around the tomatoes and replace with my untreated clippings?

    Should we just be dumping the treated clippings back in the woods or are there some plants/places it is ok to use them as mulch? And what about the clippings that are currently in the compost pile? How bad will that compost be later?

    Any thoughts you can give are much appreciated!

  2. Owlfan, My understanding is that the herbicide can remain intact for a couple of years or longer, even after composting. I would definitely rake off the clippings that remain in the vegetable garden, and spread any compost made with affected clippings back onto the lawn.

    The family of herbicides that is the likeliest culprit is for "broad-leaf weeds," which is a large category of plants. It seems to especially affect the tomato-family plants, but I don't know whether it would be safe to use around your flowers or shrubs, and it might not be good to dump them in the woods, either, unless you would don't like the woods.

    Any plants that look very ill should be removed. To be honest, if it were my garden growing food for my own family, I would pull any affected plants, scoop off the top layer of soil, and start over.

    I have read (chemical company websites) that any fruits produced by affected plants should be safe to eat. I didn't see any research cited to back that up; however, the herbicides have been approved for use on grain crops (corn, wheat, etc).

    So sorry that your garden is having this trouble. Keep me posted on how it all goes?


  3. Thanks Amy! We removed the tomato plants that were badly affected. There are 2 other tomatoes that are slightly affected, but were doing a bit of watching on them right now. We pulled off as much of the grass clippings as we could, from the whole garden. Nothing except tomato plants seems affected so far (maybe it hurt the germination of the Swiss chard, or maybe it was just that we didn't plant until April, way too late, I know). We took down the compost pile to old compost and spread the compost and clippings under the old swing set.

    Next year, we will definitely dig a bigger hole and fill in with good dirt/compost where we plant tomatoes.


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