I’d rather we didn’t use them, but I see their value and I appreciate what they can do for us when they’re used properly. One of the things that I hate about pesticides though is that, even when they’re used correctly, sometimes they can come back and hurt us in ways that we don’t expect. You have probably heard that you should not use grass clippings where herbicides have recently been used as a mulch because they could injure them. This is mostly because of the pesticide 2,4 D and other, similar herbicides for the lawn which can injure other plants if placed in the wrong spot.
Back in 2011 the herbicide Imprelis was used on many yards, especially in the Midwest, and did a lot of damage to spruce and other trees as Bert has mentioned in previous posts. We had thought that we were nearing the end of the effects that this herbicide would have, but now I’m not so certain (see Bert’s post from March 25). Recently questions have been asked about whether this stuff might last longer than we thought in compost. A few months ago I probably would have said that I doubted that Imprelis would linger long in compost, but, in part because of how long its effects take to show up on some plants, now I’m not so sure, and there are others who share my concerns (in fact, it was these guys who pointed out the possibility of compost problems with Imprelis to me). I honestly don’t know whether compost that includes trees that were treated with Imprelis (or has Imprelis in it for some other reason) would or wouldn’t be harmful to other plants, but I do know that it’s something I’d be watching out for.