University of Minnesota Agriculture student Ruth Burke is spending this summer interning at a CSA farm called Cramer Organics of Delano, MN. Throughout the growing season, she’ll share weekly updates about the experience with readers of the Heavy Table.
Part 2: “A Can of Worms”
A little non sequitur before we cut to the heart of this installment: It’s amazing how one week spent interning on a farm can rival an entire college semester’s worth of education. If this seems like a rather extreme claim, try it yourself. My summer has barely begun, but if last week is any indication, fall semester will, by comparison, be a walk in the park!
On my very first day, I was introduced to the cutworm. Anyone who gardens or farms will eventually encounter this pest, and although they are rather nondescript, their damage can reduce a freshly planted bed to nothing, overnight. It is disheartening (to say the least) to spend hours planting a bed of seedlings that you have nourished in a greenhouse for several weeks only to come back the next day and see half of them chewed off at the base of their stems.
Cutworms are the nocturnal larvae of a few different species of equally nondescript moths that have one life cycle per season. They mate and lay their eggs in late summer, then these eggs hatch and over-winter as partially grown larvae. In the spring, as transplants are planted in their beds, the larvae become active and begin living up to their namesake, wrapping around and severing the stems of young plants. Often they eat very little of the plant they destroy, making them particularly frustrating because the plant material is usually found right next to its roots. By midsummer, they burrow into the soil to pupate and emerge as moths a few weeks later.
The cutworms in the fields at Cramer Organics seem to be especially fond of our brassica crops (broccoli, kale, etc) and have even attacked some of our pea plants! When Joey (our manager, center photo below on the right) found the first cutworm of the day, she called us (the interns) over to explain that they should be killed when we find them. She then promptly squashed the thing between her (bare) fingers. I didn’t think at the time that I would have the stomach to pop the little buggers; it was really messy. However, by the end of the day, I was happily squashing them with the rest of the workers. Quite frankly, any sympathy I had for the pests dwindled apace with their voracious appetites.
Organic farms face a dilemma with pests such as cutworms, especially since cutworm moths prefer to lay their eggs in grass or plant debris in the fields. The simple solution would be to just have bare fields, but this runs counter to one of the foundational tenets of sustainable agriculture: building healthy soils. Practices involving cover crops like grasses (winter rye, sudan grass, etc.) and leaving debris in the fields over winter add nutrients to the soil and reduce erosion and carbon loss. And while there are a few organic cutworm control measures (BT toxin, beneficial nematodes, parasitic wasps), these are not always effective and can be dangerous to harmless insects as well.
In a non-organic operation (conventional or otherwise), there are various pesticides that can be applied as pre-planting treatments or post-emergence treatments — examples include Asana, Ambush, or DiPel. While pesticides are very effective at controlling cutworms, they are harsh on other lepidopteran species (moths, butterflies, etc.) and they can contribute to ground water and stream pollution. Also, applying such pesticides goes against the grain of sustainable agriculture (not to mention organic guidelines.)
In the end, you have to assess which practices lead to an overall benefit for the farm. As Joey and Katie (her daughter) pointed out, we need to think of the farm as a whole, and not always analyze individual parts. This means accepting certain weaknesses and strengthening them where you can. I find myself agreeing with them. Which means I’ll be squashing a lot of worms this summer.
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