Do you remember the movie, “Ghostbusters,” where the main characters blasted away the ghosts, time after time? According to Wikipedia, the characters used a proton pack, better known as an energy weapon or particle thrower. Spoof, the ghosts were gone. Wouldn’t it be nice to do that with weeds in your fields? Just shoot particles at the weeds, and spoof they are gone.
Well, some interesting research at the University of Illinois has been looking at blasting weeds away to assist organic tomato and pepper growers. The research could lead to tests looking at controlling weeds in kale fields. Perhaps, it could actually temporarily reduce the competition from weeds and restore light, nutrients and water to vegetable crops without the use of herbicides.
This blasting is better known as abrasive weeding, which may reduce weed biomass by 69 percent to 97 percent versus nonweeded plots, according to agroecologist Samuel Wortman at the University of Illinois. At the same time, it maintains crop yields as if you were hand weeding and reduces residuals from herbicides. In other words, weed blasting is another way of potentially practicing good weed management environmentally.
As ammunition, Wortman tested tiny fragments of organic grit, sampling granulated maize cob, greensand, soybean meal and walnut shells. He and his team used a handheld weed blaster or gas-powered air compressor that shot out these organic grit samples toward the weed seedlings. The researchers moved the air compressor from row to row, using a walk-behind tractor and slowly blasted their way down the test plots.
Throughout the study, Wortman and his collaborators measured growth of the crops, yield results, how well the blaster suppressed troubling weeds, and occurrence of disease from equipment and grit damage.
During the study, which was funded by the National Institute of Food and Agriculture’s Organic Agriculture Research and Extension Initiative, the grit severely damaged the weed seedlings’ stems and leaves without terribly damaging the vegetable crops.
When evaluating the grit types and effectiveness of the air compressor, Wortman didn’t find any major differences in what was used. “When it leaves the nozzle, it’s at least Mach 1 [767 miles per hour],” he said in the release. “The stuff comes out so fast, it doesn’t really matter what the shape of the particle is.”
Wortman cautions though that if growers were to do their own testing with this air compressor, they should wear protective eyewear since the high-powered moving particles can damage the applicator’s eyes and face.
He also advises growers to use the blaster on crops that are larger or more established than the weed seedlings. This is to avoid damage to the crop’s fruit, although a little may occur on the crop’s stems and leaves. The university indicates that more research is needed (and more studies are being conducted) to determine if these abrasions will lead to disease susceptibility.
According to the study results, plots using plastic mulch and applying one or more blasting treatments allowed the fruit to yield the same as hand-weeded plots. It even yielded 33 to 44 percent better than non-weeded plots.
This blasting machine also helps growers who intend to control weeds while also applying organic fertilizers, thus saving time and money. “We expect that abrasive weeding could contribute between 35 and 105 kilograms nitrogen per hectare [31-94 pounds per acre] to soil fertility,” Wortman said in the release. He believes that growers can benefit because they can fertilize with soybean meal and yet kill weeds at the same time in a single pass. However, he wasn’t convinced the fertilizer would be available for plant uptake at critical times.
Not all weeds are alike. Wortman’s study resulted in some weeds being destroyed more than others. For example, the smaller the weed seedlings, the better the blaster controlled or damaged them. He also found that growing points of seedlings that were aboveground, such as annual broadleaves, were more easily damaged versus ones belowground, such as grasses and broadleaf perennials.
Early testing results revealed that polyethylene mulch or biodegradable plastic mulch enhanced the success of the experiment, when compared with straw mulch and bare soil.
Wortman cautioned that the study was in its early stages and more testing was needed. He said in the release that weed blasting alone “is not a silver bullet, but it is an improvement.” Let’s face it, growers appreciate any help they can get when it comes to controlling or even blasting weeds. Of course, even if they use a compressor to get rid of weeds, growers are advised to still scout their fields regularly for weed growth reoccurrence.
The university indicates that future studies may involve testing in broccoli and kale crops. Also, Wortman and his team have developed an automatic mechanized grit applicator that they are trying out now. Can you say, “Blast ’em!”