Biocontrols and Pesticides… and Fungicides

Posted November 1st, 2007 by Beneficial Insectary

David Goudreault, greenhouse manager of the University of New Hampshire (UNH) Research Greenhouses, sent me a link in an email as a follow up to a conversation we were having couple of weeks ago about the use of chemicals, fungicides, and sprays in general, and the consequences of using such products as it concerns biological pest control agents and their sustainability.

The link he offered was to an online Greenhouse Grower magazine article written by Kansas State University (KSU) entomologist and author Dr. Raymond A. Cloyd titled “Growing Green: Impact Of Fungicides On Natural Enemies.” Check it out, it’s a good read.

This article, as I learned upon reading it, supports our latest thinking, which wasn’t original thinking, but rather it was kindly explained to me by Dr. Mike Parella of the University of California, Davis, Entomology Dept, several years ago regarding the use of pesticides and fungicides and how the indirect consequences of such pest control measures can play havoc on the good bugs.

Products such as chemical sprays, dusts, and fungicides — including many “natural” products — can negatively affect good bugs. At the time we were going by a detailed list of products that were thought to be safe, compatible, or “biorational” and we were advising growers accordingly. Dr. Parella, however, called us out on this and helped us see the light. He pointed out that even though these products are “compatible” it doesn’t mean they are safe or innocuous to the good guys. There are indirect consequences, he noted. A domino effect, if you will. Touch one, knock them all down.

The indirect consequences of this single “touch” can include taking out the good bugs by way of killing off their food supplies. If you think about it it makes perfect sense. Biocontrols require a small and sustainable food source in order to survive and perpetuate their species. This food source can come by way of pollen or other alternate food stuffs, but in most cases it is supplied by a small, inconsequential, population of pests. (I emphasized “inconsequential” because a clean growing environment isn’t necessarily devoid of pests or life in general.)

If these products negatively affect pests — as most do — if they remove this food source, these products, regardless of how safe they are, can also destroy a biocontrol and Integrated Pest Management (IPM) program. They can mess up the hard-to-achieve balance required for sustainability. Once balance is lost it is left up to us to become micro-managers. Trust this: Being a pest control micro-manager is something you’re better off avoiding. Mother Nature is way too complex for us mere mortals to get a quick handle on, and once we think we do have it down pat, that’s when we learn we were wrong. Stopping the so-called domino effect is almost impossible.

Over the years we have learned that Dr. Parella was right on target. We’ve learned that the more growers interfere, the more difficult it becomes for them to succeed. You see, biocontrol and IPM, aside from the activity of scouting, is almost a spectator sport. The bugs are the players, while we stand out of the way. We learned this by watching others start off strong, tweak things [interfere in the nature of things] along the way, only to find themselves not as well off as they were when they began. They tweaked the program to death by introducing too many short-cut, save-a-buck sprays. They ended up not saving but rather scrambling to salvage things.

The article written by Dr. Cloyd regarded fungicides and their unwanted side effects, but just about any product can mess things up. Insecticides, fungicides, herbicides, even some chemical fertilizers. The point of all this, our advice to you, keep pest control simple, be patient, and be careful not to interfere any more than you have to. A wiser investment is to scout, recognize what you see, and react then to swiftly to what you uncover.

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