No pesticides on material I compost?

Question

I read that plants that have been sprayed with pesticide cannot be added to compost. Why not? I am growing vegetables and a little pesticide is a must. I usually use all natural or organic pesticide and only use it sparingly. What would be so bad about putting this plant material in a compost bin?

Answer 1

What you mean by pesticide is a bit of garlic or neem oil not malathion or diazinon. Herbicides and pesticides can reside for long periods so must be kept clear of food humans will consume. So warnings are broadcast in very general terms. Unfortunately you use the same word to mean a different kind of toxicity. Here in Seattle we ran into a problem with the Woodland Park Zoo Doo.
The Fecal Fest has become a very popular means of supporting the zoo by gardeners but it was canceled last fall because the herbicide chlopyralid was found in the composted Zoo Doo. Chlopyralid does not break down in compost temperatures so this entire batch could not be sold because the remaining herbicide could harm susceptible broadleaf plants especially tomatoes. So now people here are very aware of the potential harm of composted herbicides.
Elsewhere the West Nile virus has been increasing general concern for spraying pesticides near susceptible individuals. Everywhere new regulations are appearing banning the use of herbicides or pesticides and the specific chemicals are rarely mentioned. Once more common sense needs to be used when specific information should have been supplied.

Answer 2

For what you are using, you are fine. The warnings are for heavier duty, longer lasting pesticides that may carry into the compost. Granted, a good compost operation should speed pesticide degredation, but few people actually run a prime compost operation, checking the temperatures frequently and turning often.

Imagine using a heavy duty weed killer, putting the material into the compost pile and then transferring an inferior compost back to the garden with the weed killer residue still present. That's why there's a warning.

Of course you don't want to be putting diseased material into the compost pile for the same reason. Without sufficient heat thru composting properly, the disease remains viable.

Answer 3

You're not suppose to use pesticides in compost because it kills the micro-organisms needed to break down the matter. Even if you are using a less toxic version, it still could mess up the balance of your process.

Also, the process of decaying causes a heat reaction which releases gases and other chemical compounds that probably don't mix well with the chemicals used in the pesticides.

Good luck!