People often ask me how we manage insect pests on our farm, if we don’t use chemicals. The answer is pretty simple: we intercrop. We bolster the plant’s natural defenses. We encourage diverse populations of beneficial insects, and if all else fails, we simply do not grow the crop.
Insect pests love it when they can find a big expanse of their favorite food. They get right in there and start munching away, having babies, and calling in all their buddies! Just a few caterpillars or mites can quickly turn into a zillion. One of our strategies for managing this is to confuse the pests by mixing up the crops. For example. Caterpillars especially love crops in the brassica family, such as kale, broccoli, and cabbage. If you plant them all together in one big field, you will be supplying an all-you-can-eat buffet! To solve this problem, we spread these crops all around the farm. We also try to “hide” them among other crops the pests might not like. For example, our young broccoli transplants are safely tucked in next to the leeks that have been growing all winter and are much bigger. Caterpillars don’t like leeks and onions, so I hope the mama moths will just fly right on over and pass by the baby broccoli. So far, so good. Not a single hole on the baby broccoli plants.
Additionally, we try to harness the crops’ natural ability to deter pests. When plants perceive the presence of a pest, they spring into action, producing compounds that may taste bad to insects, inhibit their reproduction, or possibly make them sick. These are often phenolic compounds and antioxidants that may even have a positive impact on human health. Plants also can produce volatile methyl jasmonate, which acts as an attractant to beneficial insects, further helping to manage the bad guys. It has been proven by a graduate student at the Nova Scotia Agricultural College that treating your crop with seaweed extract elicits one of the same pathways within the plant that is responsible for this natural resistance1. Our crops get a good weekly dose of seaweed extract. It helps them grow better, resist pests better and ultimately yield better!
There are other natural products that can also deter insects. Neem oil has been proven to deter many insects, as well as, in some cases, disrupt their life cycle. We often use a bit of that in our seaweed applications. Another great strategy is to ensure there are plenty of beneficial insects around, by planting rows of herbs and flowers where the beneficials like to live and reproduce. We intentionally leave rows of older crops to “go to flower”, as well as plant new types of flowering crops for this purpose.
Lastly, if a crop truly has so many enemies that it cannot be grown without applications of chemicals, then we simply choose not to grow it. It probably means the varieties available are not well suited to our environment, and that maybe growing something else is a better idea. Last year I tried to grow Amaranth. This is a specialty green that grows well in our summer heat. However, it is so prone to flea beetles that there was no way to grow it without being full of holes that ruined the appearance. I probably will not grow that one again. I have found that many types of squash are also in the same category. This last strategy is probably the best advice of all: choose crops that grow well in your area and are mostly care free. Don’t even engage in the war!
Eat your veggies,
1Extracts of the marine brown macroalga, Ascophyllum nodosum, induce jasmonic acid dependent systemic resistance in Arabidopsis thaliana against Pseudomonas syringae pv. tomato DC3000 and Sclerotinia sclerotiorum. Subramanian et. al. European Journal of Plant Pathology, April 2011.