Adventures in Organic Gardening A Toxic Mistake
by David Y. Goodman, UF/IFAS Marion County Master Gardener
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s an experienced organic gardener, I had done everything right—amended the soil with compost, planted non-GMO seeds, fertilized with cow manure from pasture-raised cattle, and so on. When the blackberry leaves started curling up into deformed fractals, I thought perhaps they’d received too much nitrogen. Then my wife’s newly transplanted tomatoes started doing the same. Probably a virus, I thought. Then the beans did it … and an eggplant. But when my mulberry tree also joined the club, I realized something more sinister might be in play. Google searches and calls to friends revealed nothing—until I came across an article in a British newspaper about a community garden struck with the same plight. Once I found one article, and a suspect, it was easy to find a lot more of the same. What had been killing my plants and those of my fellow gardeners across the Atlantic? Cow manure: that wonderful, plant-healthy, organic alternative to chemical fertilizers. But it wasn’t the manure itself that was to blame—it was a persistent herbicide inside it. The previous fall I had indeed bought some manure. In fact, I bought a double load of good rotted stuff from a local cattle farmer, spread it around my trees and plants, and dug it into the lovely new vegetable beds I had constructed for my wife. After identifying the likely suspect, I realized I’d shared some of my pile with a fellow Master Gardener. If her plants were showing the same symptoms … Breathlessly, I picked up the phone and gave her a call. “Jo? This is David. How is your garden doing?”
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“Fine,” she replied, then paused. “Actually … my tomatoes are really curling up and twisting. I have no idea what’s wrong with them—I’ve grown them in these beds for years and never seen anything like this.” “Did you use my cow manure on them?” “Yes, why?” The answer confirmed my fears. With many apologies, I revealed my suspicions and decided it was time to dig deeper into the pile of deadly droppings. Many herbicides break down rapidly. The much-maligned (probably for good cause) RoundUp is a contact-based killer and disintegrates rapidly into the environment under normal conditions. But the stuff I had used to unknowingly poison my plants was different. It was a persistent hormone-based toxin that could be sprayed on a field, eaten by an animal, digested, excreted, composted in a heap, and still kills plants. The butler in this mystery, it seems, was Aminopyralid. It specifically targets a variety of non-grass species by inhibiting their cell stacking functions, causing gross deformations and plant death. It stays in the soil for an unreasonably long period of time (estimates vary from one to five years) and does not break down under composting. If a cow munches hay harvested in a field where Aminopyralid has been sprayed, their manure becomes a plant killer instead of a plant feeder. The normal ecological cycle has been disrupted. What’s worse, it can be found in bales of straw, bagged manure, and compost—and it’s almost impossible to track the supply chain back to who sprayed what, where, and when. Most gardeners who lose their plants are likely to assume their thumb wasn’t green
enough, not that they’ve been poisoned by industrial agriculture! Armed with all this new information, I called the farmer who had sold me the manure. I asked if he’d used anything on his fields the previous year. “Just a new herbicide recommended for pigweed. It worked great, and it’s safe for the cows to eat,” he told me. I asked if he knew what it was called. He told me he wasn’t sure, but said he’d let me know. I gave him my e-mail. A few days later, I received his message that told me the substance’s name and a link to its ingredients. Aminopyralid. Case closed. Long a fixture in the area where I live, he was horrified to hear that his manure had caused me to lose my plants, though he told me no one else had called to say they’d had any problems (likely because they didn’t know what did it!). My cattle-farming friend had no idea the toxin could continue downstream—in fact, most farmers don’t. The substance does what it promises, kills weeds and keeps them dead— but the effect can carry far beyond the pigweed and brambles in a hay field. As I look across the empty beds of black soil that should have been teeming with lush green life, I’m saddened by the loss of a year’s crop. I’ve crumbled in charcoal, added some new soil from the chicken run, and grown some members of the grass family (corn) to soak up the toxins. But I won’t know if I’m in the clear until I plant next year’s beans and tomatoes. I also dug up the blackberries, washed their roots and planted them in new spots, scraped the manure away from all my trees, and gotten a refund from the cattle farmer—but the feeling of violation doesn’t go away. With Aminopyralid, organic gardeners like you and me are getting the shaft. Those of us who wish to grow things naturally and without poisons have to be savvy and stay a step ahead. Keep your eyes open. If an age-old garden amendment like cow manure isn’t safe, who knows what is? I have a sneaking suspicion God allowed me to lose a few plants so I can save a few of yours. If that’s the case, so be it. But I sure miss those tomatoes.
Printed on recycled paper to protect the environment