When Eating Greens Is Not Good For You

Reader Contribution by Staff
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A while back I asked the boss to take me off of pesticide stories because I found them too disturbing. Killer Compost is a gardener’s worst nightmare, but the story that put me over the edge was systemic pesticides in food crops. Then last week, while innocently updating my research on cabbage aphids, I discovered that commercial growers often treat collards and kale with imidacloprid shortly before harvest to make sure the leaves are aphid free. They do? Apply systemic pesticides to food crops not as a pre-plant thing, but shortly before harvest?

At three in the morning I’m awake wondering what’s going on. Imidacloprid is the systemic pesticide found to be associated with honey bee colony collapse disorder; it will outright kill bees that collect pollen from flowers treated with the stuff. I don’t think most people want to eat it.

And yet they are. On leafy greens in particular, imidacloprid levels can run extremely high. According to the most recent analyses from the Pesticide Food Network, 74 percent of lettuce samples, 46 percent of spinach samples and 30 percent of kale (conventionally grown) showed high levels of imidacloprid.

This is all quite legal. The label for Admire (a soil-applied product) says you can apply it to leafy greens up to 21 days before harvest. A newer spray-on product called Pravado specifies a 7-day period from last application to harvest.  Bottom line: Commercially-grown greens can be reared on imidacloprid applied to the soil when the seedlings are set out, and then given more to keep high levels of the pesticide coursing through plant tissues. Aphids are effectively deterred, and so am I.

I agree that cabbage aphids are a formidable foe, though I seldom see them on collards or kale except late in the fall, when the plants are old and stressed. In their prime seasons I have no pest problems with either crop that a row cover can’t prevent or cold water can’t wash off. Systemic pesticides like imidacloprid cannot be washed off, because they are in the plants’ tissues, intended to poison aphids or whiteflies.

The most troublesome aspect of all this is that the food crops in question – dark leafy greens – are among the most nutritious vegetables one can eat. As a side dish, there is no comparison between a bowl of cooked greens and an order of fries, particularly if the greens are fresh and organically grown. But what compromises are made when the kale in your favorite restaurant’s potato-kale soup came from a wholesaler’s truck? You may have a healthful food choice tainted with systemic pesticides.

The collards in my freezer are looking better than ever, and the same goes for the organic salad greens I bought yesterday. I am lucky to live in a town with a dynamic local food distribution project, Plenty!, that brings organic produce donated by gardeners and farmers to the people who can least afford to buy it.

But this doesn’t solve the problem. No one should have to accept otherwise nutritious foods laced with the same systemic pesticide that renders bees unable to find their way home. I want to see it on the label: bee-unfriendly, grown using persistent systemic pesticides. It’s a case of unnecessary chemical use at its worst. If farmers can’t figure out how to grow leafy greens without systemic pesticides, they need to find another job. 

Photo by Fotolia/Monamakela