Managing Weeds Ecologically, while NOT Breaking your Back

If you’re an organic vegetable farmer, weeds can break you. It was a lesson I learned first-hand on Saturday morning. Charged with harvesting 10 small, clean, market-ready bunches of cilantro, weeds turned what should have been a 10-minute task into a frustrating half-hour-long nightmare. Weeds obscured and out-competed the cilantro, making it challenging and time-consuming to find and snip out cilantro with stems of the appropriate length, without also snipping out foxtail, scarlet pimpernel, common ragweed, and hairy galinsoga. When weeds get in the way of harvesting, they’re cutting into profitability, which is why “every farmer needs a weed management plan!” to quote Seed Farm director, Sara Runkel.

Know your weeds. Amidst intermittent rainstorms and in especially soggy fields, students learned the first step in every weed management plan: figure out what weeds you have on your farm. This spring the rainy weather made fields at The Seed Farm too wet to cultivate for many weeks. Then, the rapid switch to 90+degree-weather quickly baked soil in many of the fields to concrete, again preventing effective cultivation. Scott Guiser, horticulture educator from Penn State Extension in Bucks County was on hand to help students identify the resulting weeddiversity at The Seed Farm.  From perennials like yellow nutsedge and Canada thistle, to annuals like hairy galinsoga and yellow foxtail, students got lots of hands-on experience identifying weeds in their natural field conditions.

Learn their ecology. Are your weeds mostly annuals or perennials? Do they have a fibrous root system or a taproot? When to they germinate? Learning all of these characteristics about your problem weeds will point the way toward effective management solutions. For example, hairy galinsoga, a common weed in many vegetable systems, is a summer annual weed with a rather delicate, shallow fibrous root system that matures from seed to flower in less than a month and has no seed dormancy. While this list of characteristics may at first make hairy galinsoga seem like a formidable enemy, Saturday’s students learned how to spot this species’ weaknesses. The lack of a seed dormancy period and shallow root system, make hairy galinsoga seeds especially easy to clean out of your seedbank using false seed-bedding, a technique where the farmer tills the soil to stimulate a flush of weed seeds to germinate. Then, the farmer returns and cultivates out each flush of weed seedlings to clean the seeds out of the soil.

Manage weeds with the appropriate (sharp) tools. Ann Adams and Liz Brensinger from Green Heron tools arrived to demonstrate the ergonomically appropriate way to hand cultivate on a small scale. Dedicated to providing tools that maximize comfort, efficiency, productivity and safety, Ann and Liz inspired hope that there are ways to effectively manage weeds for hours on end without pain. Using tools with long handles to keep your spine in proper alignment and ergonomic grips to keep your wrists in a neutral position can go a long way to prevent the aching back and wrists often associated with many hours of weeding. Tianna DuPont, sustainable agriculture educator and course instructor, emphasized proper tool maintenance to keep the effort of actually using a tool to a minimum. Clean (with a wire brush), sharpen (with a bastard file) and oil your hoe/ pruners, harvest knife, etc. often – definitely after every use. A sharp tool will take far less effort and be much more effective than a dull tool.

Get ‘em when they’re small (and definitely before they flower), is Scott Guiser’s cardinal rule of weed management. Whether you’re flaming a bed of carrots before the carrots have emerged, hand-hoeing cabbages or cultivating a field of fava beans using a tractor-mounted Williams Tool System, the best time to kill weeds is at the “white thread stage” – just after the weed seeds have germinated, but before they have true leaves. It’s not only the time when it’s easiest to kill weeds, it’s also the time before the weeds have exerted their competitive damage on the crop. If you miss them at this early stage, all is not lost, just be sure to mow them off or plow them under before they go to seed. Each weed can make thousands of seeds, so, to avoid contributing to next year’s weed woes, be sure to kill them before they set seed.

Despite the having to dodge raindrops, students seemed thoroughly satisfied by the day’s end. Having had a chance to:

• learn about a wide variety of weeds and effective organic management practices for each,
• experiment with and compare a wide variety of hand tools,
• get some hands-on experience sharpening tools, and
• examine and compare an array or tractor-mounted weed management implements

Yeawah Sano, an aspiring vegetable farmer said, “this class was totally worth the [3 hour] drive from Maryland!”