Organic Broadcaster

Market farmers share their favorite methods to thwart weeds
By Bailey Webster, MOSES


Anyone who has spent any time farming knows that weeds are one of the primary challenges of the job. For a ¼-acre urban farm plot or a several-thousand-acre row crop farm, the task is the same: manage weed pressure with as little time and labor as possible.

This can be especially challenging for market farmers who grow dozens of varieties of vegetables. Each vegetable type has its own unique characteristics, including germination time, size, growth habit, and canopy. Some vegetables germinate and canopy relatively quickly, making them fairly easy to keep weed-free. Others germinate very slowly, and are outcompeted easily by weeds. Some vegetables grow long vines, which makes mechanical cultivation virtually impossible after a certain point. To make matters even more complicated, each weed species has its own growth habits and method of reproduction, which must be taken into account.

Jed Colquhoun, a researcher at the Horticulture Department at the University of Wisconsin-Madison, explains it this way: “There are no silver bullets in organic fresh market weed management, so I advise an integrated approach that starts well before the current growing season and is based on ‘how weeds are built.’ In other words, what techniques can we use that interrupt the weed’s life cycle, minimize competition with our crops and prevent spread through seed production or vegetative structures?” Colquhoun’s “integrated approach” includes many techniques, including stale seedbedding, competitive planting arrangements, crop variety selection, resource placement to favor the crop (such as side dressing rather than broadcasting fertilizer), mechanical and hand cultivation, weed-free mulches, and mowing nearby weeds to prevent seed production and spread.

Timing is everything when it comes to weed management, and planning ahead is essential. Here’s how several market farmers manage weeds on their farms.

Tipi Produce

Steve Pincus and Beth Kazmar own Tipi Produce, a 76-acre organic vegetable farm in Evansville, Wis. They have a 500-member CSA and wholesale accounts in Madison and Milwaukee. The farm has been in operation for 40 years, so you can bet that they have seen their share of weeds. There is a consensus among farmers that weed management is a dynamic and ever-evolving system unique to each farm—and, Tipi Produce is no exception.

Even with 40 years of farming under his belt, Pincus is trying new things. He recently purchased a Treffler

The tines on the Treffler Harrow from Man@Machine maintain consistent pressure over rough ground.

Harrow, a new cultivating implement from Man@Machine in the Netherlands. Pincus saw it exhibited at the MOSES Organic Farming Conference earlier this year. Man@Machine chose the conference to introduce the tool to the U.S. market.

Pincus just received his harrow and already is impressed with how it works. “It’s a really good tool,” he said. “It’s worth the extra money and complexity.”

The Treffler Harrow is a tine weeder similar to the well-known Lely cultivator from Holland. Tine weeders are blind cultivators, which means they go over the weeds and the crop indiscriminately. They are best used on robust crops that can take a bit of rough handling (usually transplants), when the weeds are barely germinated or just at the “white thread” stage. On a Lely, there are very few parts. Each tine wraps around in a circle at the top where it attaches to the implement, essentially acting as its own spring. The Treffler, on the other hand, is much more complex. Each tine has its own spring mechanism with a tensioner, so that no matter what the conditions of the field are, the force of each tine is the same. The tines are also highly adjustable. The depth and downward tension can both be adjusted. And once it’s set up, it is very easy to use, Pincus said.

He is also really excited about another new cultivator: a KULT-Kress finger weeder from Germany. He purchased the finger weeder at the beginning of this season. By June 20, he had recouped the cultivator’s purchase price through savings on labor for hand weeding.

A finger weeder has discs with “fingers” that turn and essentially scrub small weeds from the root zone of the larger crop plant. The discs are mounted on a spring-loaded arm, allowing them to cultivate at a constant depth. Pincus uses the KULT-Kress finger weeder on transplanted crops 7-10 days after transplanting, once the roots have established. He also uses the finger weeder in combination with another KULT-Kress implement, the Duo. This is a 3-row weeder with gauge wheels, cutting discs, and side knives. On very small direct-seeded crops, such as carrots, he uses the Duo first, leaving a 3-4 inch band of weeds around the seedlings. Then, when the crop is larger, he goes through with the finger weeder to get closer to the plants.

PrairiErth Farm

Hans Bishop runs a vegetable CSA with his wife, Katie, as part of PrairiErth Farm, his family’s multi-generational, 400-acre integrated organic farm in Atlanta, Ill. The family received the MOSES Organic Farmers of the Year award at this year’s MOSES Conference.

Bishop acknowledges that weed management is a “work in progress” on their farm. He is quick to point out that weather conditions dictate practices to a large extent. They have a many-pronged approach to weed management.

Much of their approach centers on planning and bed prep before the crops are even planted. They use the stale seedbed technique, which involves preparing beds a week or more before planting and allowing the weed seeds that are brought to the surface to germinate. Right before planting the crop, the bed is cultivated lightly to kill the weed seedlings, without bringing more seeds to the surface. This technique saves time and labor spent weeding later on, and is essential for direct-seeded crops, such as carrots and beets, that have a hard time competing with weeds.

The Bishops have been careful to set up a system that works. They need to be able to use the same equipment on everything, so their beds are spaced consistently, with 1-, 2-, and 3-row spacing. Their transplanter, seeder, and cultivators are all set to the same spacing, so they don’t have to waste time adjusting when they switch from one crop to another. They have a lot of equipment, and they “use the full arsenal of tools” they have available.

Another area that the Bishops focus on is transplants. “Plants that are strong and healthy can outgrow the weeds,” Bishop said. They grow healthy transplants in their greenhouse, have a good mechanical transplanter, and irrigate right away so that the transplants have good root establishment.

This winter, Bishop built his own finger weeder, which is mounted on an Allis Chalmers Model G. He said they’re using it everywhere they can this season. The Bishops also have a KULT-Kress Duo, and like Pincus, use it on direct-seeded crops to get within an inch or two of the crop. They also have a Steketee finger weeder from the Netherlands. In addition to finger weeders, the Steketee has sweeps and knives that can be lifted up so the implement can be used as a regular cultivator.

Another favorite piece of cultivating equipment is their Eco Weeder from Univerco, a PTO-powered 3-point attachment with a seat and handles so that an operator can manually control the cultivating attachments (discs with short tines that spin). Bishop said this works well for plants with in-row space between them—the operator moves the cultivators in and out to go around the plants and meet in between. Bishop also particularly likes using an offset cultivating tractor with belly-mount cultivators. There are many attachments that can be used, including as sweeps, discs, knives, and tines.

For the times when hand weeding is inevitable, the Bishops have a few favorite hand tools. They like the Japanese hand hoe, which can be used very close to the plants with some practice. Another favorite is the trapezoidal hoe from Johnny’s, which has a beveled shape to get under the edges of plants, and sharp corners to cut through roots. They also use a collinear hoe, which is specifically designed for use in an upright position with a thumbs-up grip, riding collinear with the soil surface. It works well with low-lying crops such as head lettuce, because it slices through weeds without throwing soil. In their high tunnel, where it isn’t possible to drive a tractor to cultivate, the Bishops use wheel hoes with 5-, 8-, and 10-inch stirrup attachments.

In addition to cultivation practices, the Bishops use cover crops and plastic mulch to control weeds. They plant a lot of oats and peas in the fall, which winter-kill ahead of early direct-seeded crops such as carrots and beets. They also plant rye as an early cover crop before planting fall brassica transplants. They use plastic for long-season crops like tomatoes and sweet potatoes, which are hard to cultivate between when they grow past a certain size. According to Bishop, it’s important to get the weed seeds to germinate and die off under the plastic before punching holes and planting into it, otherwise weeds will grow up through the holes along with the crop, and must be hand weeded out.

The Bishops will host a MOSES organic field day at PrairiErth Farm Sept. 8, where several of the cultivators listed here will be demonstrated. See page 7 for details.

Foxtail Farm

Chris and Paul Burkhouse own Foxtail Farm, a winter CSA farm in Osceola, Wis. They have been farming for 25 years, and ran a 300-member summer CSA for much of that time. They grow 15 acres of vegetables, and have many old tractors and implements that Paul keeps in working order. The Burkhouses use many of the techniques described above, but like all seasoned farmers, have their own spin on things.

They, too, focus on strong transplants to get a 2-3 week head start on the weeds, and find the size differential makes it easier to cultivate aggressively. They try to cultivate before they see the weeds. They also try to time it to cultivate when the soil is starting to dry out after a rain. “Cultivating before a rain just replants the weeds,” Chris explained.

They try to stay on the tractor, doing mechanical cultivation, for as long as possible. Then they use hoes and weed standing up for as long as they can. Hand weeding is used only as a last resort.

Paul has a particular soft spot for old implements manufactured in the mid-20th century. His favorite implements are a Buddingh basket weeder, Buddingh finger weeder, and steel paddles called “weed commanders,” which act as a hilling tool for small crops like onions. They use combinations of implements to get the job done. For example, they start with the basket weeder, which is followed by the finger weeder to clean up in between the plants, and finally the “weed commander” to hill around the plants. Most of the equipment they use are no longer being manufactured, but can sometimes be found used at auctions.

The Burkhouses are big fans of cover crops, using multiple successions of fast-growing crops like oats and peas, Japanese millet, and buckwheat to reduce the annual weed seed bank. They also use cover crops effectively to suppress perennial weeds such as quack and thistle.

Paul’s advice to new market farmers is to “get ahead of the game in June because July can be a nightmare.” He also suggests that it’s possible to be too fastidious about weeds. “If they are not interfering with your crop and/or going to seed, they are a good cover, and they add nutrients and organic matter to the soil,” he explained. “Production impresses me, but a squeaky clean field does not.”

FairShare CSA Coalition

Claire Strader is a former longtime vegetable farmer and now works as a Small-Scale and Organic Produce Educator for Dane County University of Wisconsin-Extension and the FairShare CSA Coalition. She has experience growing vegetables on a small scale without mechanical cultivation, and has done some research on weed management. She has a number of strategies to recommend for weed management on a market farm.

Strader says it’s important to plan your crop rotation such that crops that are easier to keep clean are planted before crops that are harder to keep clean. This will help to reduce the weed seed bank and keep weeds from going to seed. She also recommends spacing crops carefully to allow access to adequate sunlight, nutrients, and water. Crops that are strong and robust more easily outcompete weeds, and provide canopy to inhibit weed germination.

Weeding shallowly keeps weed seeds from coming to the surface and germinating. “Rogueing” is the technique of pulling large weeds that are threatening to go to seed before the harvest is over—this keeps them from adding new weed seed to the seed bank. Similarly, mowing off the crop and the weeds immediately post-harvest helps to reduce deposits to the seed bank.

Another good weed management technique is planning a managed fallow year every fourth or fifth year. Cover crops should be used during the fallow to reduce the seed bank and improve the soil. At a small scale, where most things are done by hand, it’s especially important to keep the soil covered to minimize weed seed germination. Strader particularly favors marsh hay mulch, which is weed-free and particularly good for cool-season crops such as brassicas as it keeps the soil temperature down. She has also successfully used clover as a living mulch, interseeding it between the vegetable plants.

Although Strader was at one point interested in mechanical cultivation, she decided that her scale was too small for it to be worth it. She would have had to also use mechanical transplanting and seeding, so she decided she “preferred to keep spacing tight and do things by hand rather than using up space to accommodate the tractor and all its implements.”

One of her favorite hand tools is the Valley Oak wheel hoe, which she used for paths and widely-spaced crops. She also likes the Johnny’s hand hoe for close in-row weeding, as well as Johnny’s stirrup hoe as an in-between tool.

Strader’s advice to beginning market farmers is to “grow fewer acres of vegetables, keep the acres you do grow very clean, and use that extra land to grow more cover crops!” As she gained experience farming, she found herself using less and less land more and more efficiently, going from 3.5 acres to 3 acres with the same production. “With fewer acres in vegetables, there was less land I had to keep weeded, so overall the crops were cleaner (which helped them to produce more).”

There are some tried-and-true rules of thumb for weed management, but there are as many practices as there are individual farms. There is so much variability from farm to farm, from the soil type and microclimate to scale and seed varieties used. Weed management will inevitably involve a lot of trial and error on each farm. While there is much to learn from other farmers, at the end of the day each farmer has to decide for him/herself what works for his/her farm.

UW’s Jed Colquhoun described his favorite implements as a rolling finger weeder and a brush hoe, but then said, “In all practicality, however, I like the cultivator with the custom welds of a seasoned grower, improved with multi-generational modifications.” It’s a great metaphor for the whole farm system—successful farmers aren’t afraid to make modifications and try new methods. And, who doesn’t love a custom weld or two?

Bailey Webster is the Events Coordinator for MOSES, and an organic vegetable farmer.

From the July | August 2017 Issue


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