The popular perception is that organic farmers are at a disadvantage most when it comes to dealing with insect pests. But in reality it is weeds that can bring an organic farmer to ruin in short order. This was brought home to me again by witnessing the trials of a beginning farmer who took over the 20 acres across the road from us. Clearly hard-working and ambitious, he was, unfortunately, thoroughly unprepared to deal with the well-endowed weed seed-bank that he inherited. Growing for the low-margin, high-volume wholesale market, the first block of purchased transplants he planted out was nearly 4 acres in size (in comparison, we do more frequent plantings of only about a half-acre at a time). A week or so after he watered the newly planted field in, the first flush of weed seedlings started to appear, like five o’clock shadow on a man’s face. As the narrow window of time for mechanical cultivation came and went, it was clear that he had no means of dealing with it. Ultimately, all they managed to do was to make a tractor pass to clean the furrows out, and to station two thoroughly overmatched workers in the field with hoes who for weeks put up the good fight but never really stood a chance against the onslaught of malva, nettles, sowthistle, shepherdspurse, prickly lettuce, lambsquarters, purslane, pigweed, and wild mustard. If they managed to harvest anything off of those four acres, it wasn’t much–a very hard lesson to learn indeed.
After doing this for 24 years or so, those hard lessons are mostly in the past for us. During that time weed control is something that we have taken more and more seriously and gotten better at. On nearly all of our fields we use the “stale seedbed” technique prior to planting. This involves taking all of the normal steps to prepare the beds, but prior to planting we pre-irrigate and wait 10 days or so for that first flush of weed seedlings to emerge. Using either a propane flame weeder or a shallow mechanical cultivation pass, we kill all of those seedlings prior to planting which greatly reduces the subsequent weed pressure. The flame weeder, which uses 4 burners to cover the entire bedtop, is also useful for those slow-germinating crops that we plant directly from seed like carrots, cilantro, parsley, onions, leeks and dill. For these crops we hold off on flaming until after they have been planted and irrigated a couple of times. Because the crops take so long to emerge, we can wait until most of the broad-leafed weeds have come up before making a pass with the flamer. If we have timed things right, the crops will emerge the very next day with few weeds to compete with.
A couple of years ago I completely re-worked the mechanical cultivation set up on our old Allis Chalmer G cultivation tractor to include a set of European “finger-weeders.” Previously, we had only been able to use this set-up, which uses flat knives to undercut weeds, to cultivate between the rows of crops—leaving a 4 inch band that had to be cultivated by hand. This new configuration, however, uses rubber fingers that largely leave our transplants undisturbed while killing up to 80% of the weeds within that 4 inch band between plants—a huge improvement.
What we’ve found over the years is that we need to be smarter than the weeds — as long as we stay one step ahead, we come through the battle on top. At a time when Monsanto faces over 13,000 lawsuits from people who have contracted cancers after using Roundup weedkiller either at home or occupationally, we are happy to fight the good fight with mechanical cultivation. With luck our neighbor will chalk this crop up to experience and come back with a better plan next time.
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