Organics and insects

100_3460How does a big organic farm protect its crops from insects and disease when I struggle to beat the bugs in my backyard garden?

To find out, I visited Simple Gifts Farm in North Amherst. Simple Gifts offers more than 30 vegetables and fruits to its prepaying shareholders, and it also operates a farm store and sells at farmers’ markets. My guide for this tour was Lisa McKeag, a vegetable specialist with the Extension Service.

Every two weeks, Lisa meets with Jeremy Barker-Plotkin of Simple Gifts Farm to walk the rows and look for insects. (She’s shown in the photo inspecting a cabbage plant.) They work with five apprentices, each of whom is responsible for a different family of vegetables.

Biological and cultural control is the goal, Lisa said, emphasizing prevention rather than responding to emergencies. This includes knowing about the life cycles of specific insects, including when they emerge and where they overwinter. It involves knowing which flowers to plant that attract beneficial insects such as ladybeetles and green lacewings, Lisa said. It means crop rotation, monitoring pH and giving plants enough nutrition.

She offered a tip on my nemesis, the squash vine borer moth, which beat me this year despite my applications of petroleum jelly and row covers. The moth typically emerges after 900 degree-days have been accumulated in the growing season, though this year to came out after 700 degree-days, she said. Next year, I’m going to calculate degree-days so that I know when to cover the zucchini plants.

Lisa said there had been no confirmed reports of late blight on tomatoes this year, but on Thursday there was one in Franklin County. If cooler weather next month combines with high humidity, there could still be an outbreak, she said. I had suspended my spraying of liquid copper on my tomatoes, but with this report of blight nearby and a wet, cooler period on the way, I sprayed Thursday night.

At Simple Gifts Farm, tomato varieties that are resistant to late blight have been planted as insurance. I grew two of them, but they didn’t produce as well as others.

I learned about “economic thresholds.” This is the amount of insect pressure a crop can sustain before a farmer must respond. For caterpillars, Bacillus Thuringiensis or Bt is an effective organic spray that Simple Gifts Farm uses when caterpillars infest from 15 to 35 percent of plants, but it doesn’t harm bees, Lisa said.

Massachusetts farmers have had a problem this year with cabbage aphids, which also attack broccoli and Brussels sprouts, Lisa said. Organic farmers should respond when more than 10 percent of plants are infested, usually with an  insecticidal soap such as M-Pede. she said.

Simple Gifts Farm also rotates its vegetable plots to foil insects, and uses cover crops and compost to keep plants healthy and thus less susceptible.

Jeremy, who was on vacation when I visited the farm, “really hates his aphids,” Lisa said. I hope they didn’t ruin his vacation!

For new readers of this blog, here’s a quick overview of 120 past posts in 13 categories, including simple living, frugality, living without, gardening techniques and climate change.


One thought on “Organics and insects

  1. Pingback: Past posts: A simple living index | Adventures in the good life

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