I don't spend much time on garden pesticides on this site because I know most of my readers are already interested in alternatives, but I thought I'd better post a few notes for the gardening newbies out there.
This article is about the downsides of garden pesticides with respect to the garden itself (the health implications for us would be an entirely different article).
When I was younger, I spent the better part of a decade maintaining a 9 hole, par 3 golf course owned by my parents. I sprayed pesticides often. The enemy on the course greens was a fungus called dollar spot. The main pesticide ingredient was chlorothalonil. It killed the fungus really well for about 7 days until I had to come back and spray more.
So yes, I’ve used pesticides.
Pesticides kill living things. “Cide” means to kill. Herbicides are specifically made to kill plants, but we’re not talented enough to create these poisons to kill only their target kingdom, so herbicides often kill or at least hurt animals, bacteria and fungi, too.
Of course, bactericides and fungicides and insecticides kill or hurt animals and plants, as well. For example, the fungicide I sprayed on the golf course greens was deadly toxic to fish, too.
The pesticide manufacturers tell us these poisons will be broken down by the microorganisms in the soil. This may be true if we have a healthy, diverse soil food web, but every time we or our neighbors spray, we decrease the number of healthy, happy microbes until eventually, there are very few of them left to perform this important function.
Even when it rains, we get unbelievably high doses of pesticides from thousands of miles away.
Many garden pesticides have indeed done a great job of killing all insects, diseases and weeds for awhile, sometimes even for decades. Eventually, the predators figure it out and come back with a vengeance. This time the chemicals don’t work as well or at all.
In the meantime, the pesticides have done a dandy job of terrorizing the organic soil environment, ensuring that weeds are the only plants that will grow there and that plant predators are the organisms that flourish. Using a herbicide just prolongs weed problems.
We’ve already seen how microbes are vital to the very existence of our organic gardens, so we know we don’t want to kill them. Plants are also hurt by garden pesticides to the point where protein synthesis stops, soluble nitrogen and sugars increase, and predators are invited to dine. In Healthy Crops, Francis Chaboussou does an excellent job covering this process.
Animals - our fertilizers, our seed dispersers, our pollinators, birds, bees, butterflies and everyone else - are hurt, too. We know that certain pesticides contribute to colony collapse disorder in bees.
Nearly 100% of rivers in North America and probably the world have pesticides in them and the majority of wells do, too. Many lakes and rivers are unfishable and undrinkable. It would be good idea to stop using garden pesticides. In my view, there’s never a good enough reason to warrant using them in a garden, especially in a vegetable garden
In addition to the fact that I don't spend much time discussing pesticides on this site, I also don't spend much time talking about "organic" pesticides or alternatives to pesticides because it totally misses the point, which is:
That's what this website is all about, so that's what I'll be getting back to next week.