Fight weeds with steel, fire, and electricity
Mechanical weed control is experiencing a renaissance on the farm. Management strategies have largely been dominated by herbicide applications, but long-term reliance has created its own obstacles. Now, electricides, flame weeders, and tine or finger weeders are gaining ground.
While it may seem daunting to incorporate steel, fire, or electricity into your weed control strategy, Sam Hitchcock Tilton, horticulture instructor at Lakeshore Technical College in Wisconsin, says they are great tools to have in your toolbox.
“The fact is, when a piece of steel contacts a weed, it is usually going to kill it – and it’s always registered for use. There are no restrictions for running a piece of steel through the field. With chemicals, you might not have the right one, there might be a resistance issue, or your fields might be too wet or dry for an application,” Hitchcock Tilton says.
If your farm is certified organic or you’re growing a new crop like hemp, physical weed control is a solution to the limited number of reliable, registered chemicals. Often, physical weed control can be cheaper than paying for herbicides.
Mechanical Weeding in Row Crops
Matt Sattelberg, who farms with his brother Ben and father Jim, bought 500 acres of certified organic ground near Unionville, Michigan, in 2002. Since then, the trio has transitioned all of their 2,400 acres to organic. They raise a variety of corn, edible beans, and soybeans; sell seed and fertilizer; and are distributors for an Austrian line of Hatzenbichler tine weeders.
The Sattelbergs began their organic operation as a way to subsidize their income but the ground value, soil type, and concentration of land close to their home farm led them to narrow their operation’s production to organic only. They’ve experimented with a variety of weeding tools and keep many on hand to be used under the right conditions, in the right combination, which changes from year to year.
Matt and his family farm proactively scout the fields regularly because mechanical weeding tools work best against early weed growth.
At preplant, they will prepare the ground with a field cultivator, making two or three passes over the course of a few weeks, which warms the soil and flushes out any weeds that have already germinated. At 24 to 48 hours after planting, the Sattelbergs will make what they consider to be one of the most important passes over the fields using a tine weeder or harrow to break up the top layer of the soil in the seed trench where most of the weed seeds are left to germinate.
Once the crop emerges, about 2 to 4 inches for corn or the first trifoliate stage for soybeans, they tine weed again and continue to evaluate the weed pressure throughout the season.
Tools Work Together
“Between the rows where there isn’t a crop, anything standing can be killed. In the row, your tool must be able to kill the weeds and not the crop,” Hitchcock Tilton explains. “To be successful, you must have selectivity, which is achieved by a size difference between the crop and weed. The difference could be above ground by height or below ground by root anchorage strength.”
Size differences are created using a progression of tools from pre-emergence on and by reducing the weed seedbank. Hitchcock Tilton recommends designing crop rotation timing and type of tillage to target problem weeds when they are most susceptible in their lifecycle. Ecological weed management strategies like this take little time and deliver a big payback.
As for tools, electric, flame, and finger weeders all have different functionalities but are better when used as part of a system.
Electric weeders kill by contact, running over the crop canopy and zapping the weeds that are taller than the crop. However, an electric weeder is often considered a rescue tool for the latest stages of crop growth. If a field already has a dense weed population that is towering over the crop, it is difficult to fight.
Finger weeders are very capable of being selective and are the most economically sound. A pair of finger weeders can be retrofitted onto an existing row crop cultivator so you don’t have to buy an entirely new piece of equipment. They also do not have the costs associated with fuel and generating electricity for flame and electric weeders.
Flame weeders are effective in monocot crops like corn. When a corn plant emerges, its growing point is protected, so it can withstand some burning and not take a yield hit. However, flame weeding may not be as effective against grassy weeds for that same reason.
Hitchcock Tilton says flaming is most effective as a stale seedbed pass. “For a tool to be selective, there needs to be a size difference between the crop and the weed. One way to ensure that is to practice stale seed bedding so that after you plant, but before your crop emerges, you can do something to kill the weeds that have emerged before your crop.”
To implement this strategy, make a pass over the field with a flame weeder or tine harrow after the crop is planted. The pass will kill the weeds and allow the crop to emerge without competition. The weeds will be set back, creating the size difference, and an opportunity for a variety of weed control tools to be used in the following weeks.
Setting Yourself Up for Success
Mechanical weeding relies upon the success of many other management decisions on the farm, like straight rows, properly adjusted equipment, and uniform conditions like soil tilth, seeding depth, and other environmental parameters.
“As farmers, we are constantly told the new hybrid technology makes it more attainable to produce higher yields and better quality crops,” Sattleberg says. “In turn, we have seen that precise seed placement enhances the opportunity to obtain these impressive yields, but if we don’t make the proper adjustments to our mechanical weed control, we chance thinning our perfect stand and invite more room for weeds to grow. In short, if you spend $40,000 on planter upgrades to have a perfect stand and don’t use weeding tools that are highly adjustable and precise, you are shooting yourself in the foot.”
Balance is key. Sattelberg says it doesn’t take much to run a tine weeder, but it does take a lot of effort and expertise to keep adjusting for perfect selectivity. The tool has to be aggressive enough to kill the weeds and also precise enough to avoid unintentionally killing the crop. And the soil has to be fertile enough to grow a crop, which also means it’s fertile enough to grow a weed.
Maintaining that balance is also what keeps the Sattelbergs and Hitchcock Tilton on their toes and out in the fields.
Just like there is a spectrum of herbicides for different types of crops and growth stages, there is a spectrum of weeding tools. When used correctly, the lost art of mechanical weeding comes back to life.
The fourth annual Midwest Mechanical Weed Control field day, a virtual event this year scheduled for September 2020, is hosted by Hitchcock-Tilton, The Land Connection, and Practical Farmers of Iowa.