As an organic farm, we’re always looking for natural ways to combat insect pests. In the 15 years or so that we’ve been farming we have rarely resorted to using any of the wide assortment of organically approved pesticides that are available. Rather than spraying a crop with something that will impede or kill a targeted pest, most of our pest control methods are more indirect. We rotate a diverse array of crops in small plantings through the different fields of our farm so that pests don’t get to feast on large blocks of their favorite food over a long period of time in one place. We plant potato crops into fields with the dreaded symphylans in the soil because they produce a natural toxin against symphylans. We grow our own seedlings in our greenhouse and try to assure that our plants are well-tended and healthy so that they are more resistant to insect onslaughts. We use row covering to keep flea beatles off and cabbage maggots out of the soil by our susceptible root crops. And we depend on our native insectary hedgerows to provide habitat for beneficial insects that will keep the populations of pest insects in check.
On our home farm, we have a long hedgerow that runs most of the length of the farm along the border of the farmed portion and the part that is in Conservation Easement. Hedgerows can serve many useful purposes — this hedegerow provides excellent erosion control, in addition to the insectary habitat. We planted another hedgerow along the border between our farm and our neighbor’s road that also helps keep dust away from our crops. We also have hedgerows on our leased property at the Redman House. They provide a welcome row of native bushes in the midst of the uniform agricultural fields in the surrounding area.
Our hedgerows consist of all native plants, so after the first couple years after planting, we don’t have to water them anymore and they thrive without much tending. Our oldest hedgerow is more than a decade old now and has mature plants that are beautiful as well as providing good habitat for predatory wasps, lacewings, spiders, and other beneficial critters. I took a walk along the hedgerow yesterday with my camera in search of insects to photograph. Unfortunately most of the insects I found were too fast for my camera to capture, but I did get a few snapshots of these inhabitants of our farm who unknowingly help us out while quietly going about their business.
Some years ago, a UCSC graduate student used our hedgerow for some research. She was interested in finding out how well insectary hedgerows really work for providing pest control in a farm field. She wanted to know how far away from the hedgerow its benefits might extend. To this end, she sprayed some innocuous fluorescent dye on some of our hedgerow plants. Then she set up insect traps at different distances into the farm field—50 ft., 100 ft, 200 ft., etc. She then looked at the insects she caught in each trap under UV light. If the insect had walked in the dye on the hedgerow plant it would glow and she would know that it had come from the hedgerow.
The results were as one might expect—the number of beneficial insects that went from the hedgerow to the farm field decreased the further from the hedgerow the trap was set. The most interesting thing I found out from this research, though, was the sheer numbers of beneficial insects that are out there. For instance, there are hundreds of tiny species of wasps that prey on farm pests. The last we heard, she was still identifying subspecies of predatory wasps she had trapped several years later.
As farmers it’s good to train ourselves to look closely at small things we might otherwise easily pass over. It is often the things we can’t easily see that tend to control whether our crops do well or poorly.
Photos: (1) Our hedgerow of native plants including ceanothus, quail bush, elderberry, sticky monkey flower, Pacific dogwood, coffee berry, giant buckwheat, hedge nettle, clematis, toyon, California sage, holly leaf cherry. (2) coffee berry. (3) sticky monkey flower. (4) egg mass on ceanothus leaf. (5) little blue wasp. (6) unidentified (by me) insect on hedgerow 🙂
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