Contaminated Compost Part Two

It’s hard to picture a truckload of manure labeled “Not intended for use as compost”, or “Use at your own risk”, but it might be helpful as more farmers begin to use herbicides containing picloram, a chemical with persistent activity that can kill weeds for up to two years. For whatever reason, studies show the chemical has no known long term affect on mammals. The extension website listed about 23 trade names for these herbicides. Surmount and Grazon are the two best known, but there are also others like Gunslinger, and Hired Hand.

Gardeners are learning to ask quite a few questions.

How long ago were the fields sprayed? How long has the compost been rotting?

What type of soil is the mulch or compost being applied to?

Rodney Leech, Virginia Cooperative Extension agent for Bath and Highland talked about the problem.

“There’s all kinds of variables here, so it’s hard to pinpoint it, and fresh manure has been used forever.”

Asking very specifically what has been sprayed on the field where the mulch was taken, or on the hay the animals ate where the manure came from, is the first step. What else can gardeners do to protect their crops from the herbicide?

One suggestion is to use some seedling starts as tests. Spread a sample of the compost you plan to use onto the six-pack, or tray of starts, and within a week the plants will show whether or not they will survive.

Once a whole garden plot has been contaminated, it takes a longer to restore it to health. Rodney Leech continued.

“I have had folks that have used this product and have actually sprayed the weeds on their garden, and actually ruined their garden for a year. And they have not been able to plant in that area for at least a year, sometimes two. And the way that we check that is, we have them plant some green beans around where they had sprayed to see if they are sensitive before they plant the whole garden, and once they are able to have another crop, then they can plant it. It can last a good while. “

In a perfect world each producer would know what was on their crop of hay, or in their animals’ manure, so those growing vegetables wouldn’t need to do the background check. Some of your sources may be able to report what their hay or manure has been exposed to; others may not.   The FDA doesn’t keep an eye on what cattle and horses are eating.

When asked what responsibility the users of picloram-based herbicides might have, Rodney Leech responded.

“There are precautions on the label for producers. They need to pass on that information to people that they used Grazon or Surmount, or whatever they used,

if it has that persistent activity, because this has been a problem the last several years.”

A local network of market growers could serve effectively to get the word out about which compost and mulch NOT to use.   The message certainly is not to give up on “black gold”; it’s simply to choose carefully, and ask the relevant questions.  The Virginia Cooperative Extension website has more information on this including a list of most frequently affected plants, and the symptoms they show once they are affected.   For that link click here.

Rodney Leech concluded. “Pesticide (or herbicide) usage can be a really good tool for us, but it can also be our worst enemy if it’s not used in the correct location.”