Weed Control – or Loss of Control – in Mid-Summer
Becky Maden is the Assistant Farm Manager at Intervale Community Farm (ICF), a thriving member-owned CSA farm in its 21st season of growing organic produce in Burlington, Vermont. Becky has worked on several diverse vegetable farms throughout the country and around the world. At ICF, Becky is either found in the greenhouse, on a tractor, or jogging between the two. She also writes the farm newsletter, Bottom Land News. In her time spent away from the farm, Becky loves to travel, write, bike, run, ski, and cook bounteous meals with glorious produce.
Weed Control – or Loss of Control – in Mid-Summer
This morning I got an email from a dear friend who is farming for the first year on new land. With no time for her usual warmth, she simply wrote: Drowning in hand weeding and can't keep up. Tool bar I got this year isn't really working on my International Harvester. Do you think this looks like a good move or a stupid move [referring to an Allis G cultivating tractor that was for sale] - would have to take out another loan, so don't want to make any hasty moves.
All of our farms and gardens are cresting into July madness, where food crops and weeds collide in a decisive battle of wills. Gone are the early May days when nicely transplanted rows of green and red lettuce were the only colors freckling the field, where the soil was a cakey brown simply waiting for the carrot seeds to gracefully raise their cotyledons towards the sunlight. Now, with these solsticey-long days and moist, warm soils, conditions are perfect for weed growth. Any bare soil is quickly covered in a haze of amaranth, crab grass, and, if you are unlucky (but normal), galinsoga. What food-growing person doesn’t feel like they want a magic bullet to combat these rampantly growing weeds? Taking out a loan for a new cultivating tractor, or even briefly contemplating the wonders of herbicides, is where our brains dwell this time of year, especially as the window of opportunity to control the weeds closes in.
Which brings me back around to that endlessly troubling question about how do you control weeds on an organic vegetable farm? Our farm manages 55 acres of land organically, which has forced us to manage weeds with a few broad guiding principles:
- We try to manage our weeds as a population with the long-term weed seed bank in mind.
- We try to use the appropriate mechanical cultivation tools for our scale and we ALWAYS precede hand weeding with some form of mechanical cultivation.
- We acknowledge that we are never going to eliminate 100% of our weeds (although we do aspire to be the Nordells!) and we try to humbly maintain happy lives nonetheless.
Weed Pressure and Whole-Farm Management Decisions
On our farm, we try to manage weeds with a big picture consideration throughout every stage of planning, planting, cultivating, and cover cropping. Weed pressure is a large factor in determining which crop goes into which field, what cover crop follows a vegetable crop, and how many passes we make over a field before the crop is planted.
Two examples from our farm illuminate how weed pressure influences our cropping decisions:
In 2011, we had onions in one section of a field which we grew in plastic mulch and kept relatively clean of weeds. We harvested the onions, pulled up the plastic, and planted a solid fall/winter cover crop. Very few weeds set seed, leaving us with a clean field going into 2012. Knowing that we had low weed pressure in this field, we planned to seed our salad mix there this season, which we direct seed and like to keep absolutely weed free. Prior to planting the salad mix, we prepare several beds in advance by shallowly basket weeding them in order to disturb just the top ½ inch of soil and force weeds to germinate. When we seed the salad greens, we flame the weeds, cover the bed with re-may, and return to harvest in a couple of weeks from a pretty weed-free bed. The key to our salad mix luck is keeping several beds ahead of ourselves with the basket weeding, allowing weeds to germinate and then die in advance of planting.
Winter squash is a big acreage crop for us. We grow most of it from transplants, and count on it establishing itself quickly, vigorously, and shading out any weed competition about a month after transplanting date. We simply can’t afford the time or money to do more than a couple of tractor cultivations and one quick hoeing pass with the crew through the field before the canopy of squash leaves shades the soil underneath. If we miss our opportunity to get through the squash before it’s too late, we suffer from an ugly, weedy squash field. As of this article, we are just finishing our one and only hoeing trip through our two acres of squash; after that, we cross our fingers and hope we did a thorough job.
We treat winter squash and salad mix very differently; and between them is a spectrum of crops that require some blend of precise weed control and quick, big picture weed management. Carrots and other small seeded crops we treat like salad mix; corn, beans, and other cucurbits fall more toward the winter squash end of things. It’s not that we don’t love the larger crops or that we don’t consider them profitable: it’s just we can harness their vigor to help manage the weeds.
Appropriately Scaled and Well-Timed Mechanical Cultivations
One of our farm staff told me that for nearly a whole season, she thought her previous boss was being sarcastic when he said he was going out to “cultivate”. Like many words derived from agricultural roots, “cultivate” has morphed in our common parlance to refer to the nurturing of our intellect rather than the original meaning, which is “to prepare…and use for raising crops.” When vegetable growers toss this word around, what we usually mean is weed control.
There is a vast array of tools and set-ups for farmers to attach to either the belly or the rear of a tractor to battle weeds, and these choices depend on the crop, the soil type, moisture, weather, and weed pressure. However, the real key is well-timed cultivations. For instance, missing a quick pass over the field with a flex-tine cultivator when the weeds are at the white-thread stage means a flush of weeds will pop up and need to be managed with slower tools like baskets, knives, or even hoes.
Accepting a Weed Population and Living (Humbly) With It
In 2010, researchers from the University of Maine did a study of weed seed bank populations on a number of farms around the Northeast. On our farm they tested four different fields, some of which have been in vegetable production for over twenty-five years with various managers, others which we just brought into production a few years previously. The variation in results was stunning: counts varied between 4,000 weeds per square meter in our newest field to 138,000 weeds per square meter in our oldest field. Trying to grow anything that’s fighting against 138,000 highly adapted weed seeds seems discouraging; indeed, we have our new crop of strawberries planted in that field right now, and we are on a constant campaign to weed them. The truth is, those strawberries won’t ever be completely clean, and we don’t have the person-power to stop every single tricky galinsoga from setting seed in that field. As each day ends, I see weeds left with their hairy little roots still lodged in the soil, and I always want to just keep knocking them back. But I can’t. I don’t. Every day is a practice of knowing when to stop, of knowing when I can look at the weeds, allow myself to feel cranky for a minute, and then head to the lake for a swim and eat a feast from my own vegetables.
On a more practical note, we occasionally make a decision to forego a crop because we lost the battle to weeds, and this is most likely the time of year when we make those decisions. We can make quick calculations that take into account the value of the crop versus the amount of time and money we would spend rescuing it. If the calculation doesn’t come out in our favor, we disc the crop in. Seed costs are a negligible loss compared to labor.
We also make decisions to not weed crops, or to make them a lower priority, as they get closer to their harvest time. For instance, our spring head lettuce was well-established with plenty of light and fertility but had a pretty good flush of weeds between the plants. We knew we’d harvest the lettuce before the weeds set seed, and we knew we’d get beautiful lettuce from the field. We also knew that we had many other crops that needed our attention, so we swallowed our pride, left the weeds alone, harvested the lettuce, and quickly disced in the remaining weeds. We didn’t increase our weed seed bank and we got a good crop out of the field, so no harm done.
When I tell people that I’m a vegetable farmer, the most common reaction is “oh, that must be the most satisfying work!”; and indeed, leaving my job every day with an abundance of beautiful food and happy customers is incredibly satisfying. But what I consider to be my real work is managing soil and crops – indeed, truly cultivating the soil – and this work never feels complete. Every evening when I depart the farm, I feel like I’m turning my back on something urgent. For me, weed control – especially in July – is a lesson in achieving balance between intelligent effort and humble acceptance.
So what did I tell my friend? I told her the tractor looked cool. I also that (as I know her to be a perfectionist) I am sure her farm looks fantastic, and that on two acres she can’t expect to kill every single weed. I’m sure the tractor will help her tremendously in her long-term goal of weed control, but I hope that in the short run, she knows that June and July are tough months to feel satisfied with weed management, even with all of the proper tools. Maybe someday we will out smart the weeds, but for the moment, I live in a state tipping between manic-paced work and humble acceptance as I witness the speedy green unfurling of summer.