A client sent me the following link to an article from Mother Earth News about how a herbicide called Milestone (aminopyralid  is the active compound) which has been used to control weeds in hay fields has managed to get into compost because the affected hay has been feed to cows and the herbicide passes into their manure which is then collected by people who make the compost.

The herbicide if present in large enough amounts can severely affect an number of vegetables but especially tomato, beans and peas. The affected plants will usually not die, but will produce no or few, low quality fruit.

The article was written in 2009 and mostly concerns this problem in England, but I’ve done some additional research and it is still a problem currently in the U.S. If you are getting compost from a source you don’t know well, there is a simple test you can do to find out if you compost has a problem. It could even be a nice experiment to do with your kids to introduce them to scientific inquiry.

Of course, if you’re making your own compost, from your own yard, you don’t have to worry about this. Composting is easy, give it a try.