Contaminated Compost can kill gardens

If you are a gardener, and have not heard the names Grazon, or Surmount, remember them now. We think of compost as “black gold”, the wonderful, richly organic substance, often easy to find for free because farmers who keep animals in barns need to clean them out. In the last several years however, that “black gold” can be contaminated by herbicide used to spray fields where animals graze, or that are sometimes cut for hay. Picloram is the chemical that comes through in the hay and manure and it kills whole gardens just as well as it kills weeds.

Rodney Leech, Virginia Cooperative Extension Agent for Highland and Bath, noted the problem has increased with the popularity of these herbicides with “persistent activity”.

“It is a terrible thing because if you’ve done all the work to plant a garden, and you’ve tried to use what you thought was an organic product, you’re not big on using pesticides, then all of the sudden you have everything die, that’s coming from something you thought was safe, it’s discouraging.”

For some market gardeners it may be more than discouraging; it can mean significant financial loss.

“Those products are used on permanent pastures mainly, but they have some very persistent activity which makes them really good on keeping weeds like thistles from reoccurring throughout the season. The problem with that is, if some one would make hay, and sell the hay as mulch, one of two years later that chemical activity is still in the soil through that mulch. So we have to be very careful, and we really need to know where our mulches come from. “

Where they come is complicated by the fact that a horse operation sometimes buys hay from more than one source, and may not know themselves what is in the hay. Even which part of a large manure pile could affect a vegetable crop differently if the part the gardener takes from hasn’t been rotting as long as another.

Leech continued.

“On the labels of these products it talks about persistent activity of lasting one to two years depending on the soil.”

What are some preventative steps farmers, or barn managers, can take to make sure they are not harming local fruit and vegetable producers?

“If they’ve got a tremendous problem with weeds, and they’ve sprayed the whole field, and it may have been a pasture, and they had a good season and decide to cut hay on it, and then they fed the hay to confinement animals and take that manure. The steps on that, they’ve just got to think a little bit, ‘okay, I’m using Grazon, I want to make sure that none of my manure comes off the farm.’”

Part two of this pair of stories describes a couple of methods gardeners can use to make sure the mulch or compost is safe for their plants.