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Flamers, electrically charged innovations expand weed-fighting arsenal

By Tony Ends

Harnessing elements of nature, like intense heat or electrical charges, to dispatch weeds and kill bugs continues to find growing application and interest in farming at all scales of production. Small equipment operators tending specialty crops and expansive row-crop grain farmers—both organic and conventional—have found themselves drawn to a flame or turned on to “zapping” what confronts them in the field.

“We started working with smaller equipment in 2 and 4 rows,” said George Gogos, who brought decades of research experience in heat transfer, fluid mechanics, and combustion science in 2007 to flaming study and development at the University of Nebraska. Gogos and his university colleague Stevan Knezevic, an agronomy specialist in plant physiology, weed, and production systems, presented a workshop on flame-weeding at the 2020 MOSES Organic Farming Conference, along with organic farmer Derek Shrock of Sandy Ridge Farms in Tampico, Illinois.

“It’s 12- and 16-row flaming units for 1,000, 1,500, 2,000 acres, that are now selling the most,” Gogos said, in an April phone interview about flaming. Many factors are spurring this interest, he explained. Herbicide-resistance vexes conventional grain producers while organic farmers face cultivation challenges from wide swings between wet springs with mud-clogged fields and moisture-starved, droughty field conditions later in the season. 

Equipping farmers with ever-better flaming and electrical-charge cultivation (separate, promising areas of research and use) doesn’t solve all problems for all weeds or circumstances. Yet farmers adapting to the different technological improvements of both are finding benefits.

“My dad, Victor, built our first flamer back in the early 2000s,” said Shrock, who now manages 1,400 acres of diverse crops with family and hired help on land about 40 miles east of the Quad Cities. Shrock, who has expanded from 8-row to 16-row flaming for corn, also uses rotary hoeing, tine weeding, various cultivators, and a Weed Zapper in crops as different as dry edible beans, peas, pumpkins, sweet corn, popcorn, and wheat, through all kinds of weather conditions and weed pressures.

Shrock purchased and added a Weed Zapper to his weed-fighting arsenal after visiting an annual conference trade show in Missouri two years ago. He has used it to kill weeds on his own and neighbors’ farms—2,000 acres total just last year.

Electrical charges along copper rods on the Weed Zapper’s front-mounted boom conduct with moisture in weed plants on contact and kill them within days. A PTO-driven generator trails behind the tractor on a three-point hitch, furnishing the electrical charge. Coulters help ground the equipment’s operation.

The greener and thus, moister, the weed, the more effective the Weed Zapper is in destroying by electrical charge the plants that compete with crops for sunlight, moisture, and nutrients, Shrock explained. Woody-stem and low-moisture weeds with less conductivity prove more difficult, sometimes impossible, for the Zapper to kill, he added.

Shrock prefers to run the Weed Zapper twice over fields within a season. He emphasized the importance of getting at the weeding early while tender new weeds are green and moist. In 18 hours of Weed Zapper operation, Shrock used about 150 gallons of fuel, a cost of 1.5 gallons per acre. 

The Weed Zapper’s manual has more than 100 pages of step-by-step operating instructions, many photos, and numerous precautions. It is available for free PDF download at theweedzapper.com/about.

The University of Nebraska’s Gogos and Chris Bruening, a design engineer, formed Agricultural Flaming Innovations, an enterprise dedicated to research, develop, and manufacture equipment that helps farmers control weeds in corn, soybeans, sunflowers, and sorghum crops.

“Cultivation and hoeing don’t control weeds within the row, where they compete most with the crop for nutrients,” Gogos said. “Flaming with well-designed equipment can eliminate all weeds—even those within the row. This can mean major yield increases compared to mechanized weed control alone.” 

Flamers use intense heat (more than 1450 degrees F), not ignition, to disrupt cell function and rupture cell walls in weed plants, killing them within days of exposure. Crops like corn and soybeans have longer, more heat-tolerant stalks in their later growth stages. Selective treatments, timing, and specialized flaming equipment help protect crops, while effectively dispatching weeds, Gogos said.

Hoods developed to cover torches in rows cut heat loss, lengthen exposure times at higher temperatures, and shield against wind, which can disperse heat and curtail flaming’s effectiveness. With tractors traveling 3 to 5 miles per hour across rows of plants just inches apart, flaming equipment must maximize heat exposure and effectiveness with each design feature.

Electronic ignition and detection have made flaming equipment operation easier and safer, too. These systems can monitor the torches and reignite a torch if it extinguishes during flame cultivation.

A crop is not exposed to the high temperature when flaming is employed to kill weeds during that crop’s pre-planting or pre-emergence. Yet when flaming is used in early growth stages, the crop must either be able to recover quickly from any flaming damage (such as young corn), or much more tolerant of heat than the surrounding weed species (as with young soybeans).

Specialized practices, timing, and equipment help effectively address concerns, Gogos said. He put great emphasis on safety in equipment design and operation, adding that he’s seen unsafe fabrications and practices in field-use. 

“Flame weeding can reliably control weeds within the crop row, making it an excellent complement to mechanical cultivation,” Gogos stated. “Adding flaming to existing cultivation methods can eliminate the need for hand-weeding, which can lower operating costs for the farmer.

“Even more important, flame weeding can, through improved control of weeds growing within the crop row, increase yields up to 25 to 30 percent, compared to yields obtained with cultivation alone.” With that boost in yields, it’s possible a producer could cover the purchase price of flaming equipment in a single season if it’s properly used with the right timing to weed several hundred acres of certain crops.

Agricultural innovators were building and patenting flame cultivation, first pulled with teams of mules or horses, through sugar cane fields in the 1850s. Historic use as flame cultivation unfolded, first fueled with kerosene and oil, expanded to cotton crops in the 1930s and 1940s. 

Flame cultivation, in particular, has ebbed and flowed with development—and prices—of fuel types. Propane, which is a popular fuel now, was not commercially available in the United States before 1911. A byproduct of natural gas and petroleum refining, propane has seen its prices fall more than 22 percent since last March, according to the U.S. Energy Information Agency. While propane prices can vary considerably from state to state, EIA reported the national average in March was at $1.869.

Millions of especially rural homes rely on propane fuel for heat, and winter severity greatly affects prices from pressures on home-heating supply and demand. Propane prices hovered around $1 a gallon nearly or most of a decade through the 1990s. They peaked around $4 in 2014, but have fallen with most all fuel costs from global impacts and international developments since.

Of eight main fossil fuels EIA has compared, propane comes in second behind its parent source, natural gas, in carbon dioxide emissions, according to eia.gov. Propane, which is a cleaner-burning, lower-carbon fuel, is not toxic to soil, water, or its handlers in open spaces.

Gogos, Knezevic, Bruening, and others contributed to an informative guide published in 2014 by the Propane Education & Research Council. This 33-page manual has several particularly useful charts, including tables for propane dosages in gallons per acre as a function of propane pressure and application speed, and a list of broadleaf and grass weed species, their growth stages with corresponding heights and various dosages of propane needed to obtain 80 and 90 percent weed control with broadcast flame weeding. The guide is available as a free PDF download at bit.ly/PropaneFlameWeeding.

Tony Ends is a writer-editor for the USDA Animal and Plant Health Inspection Service. He and his wife, Dela, own Scotch Hill Farm near Brodhead, Wisconsin. 

 

 

From the May| June 2020 Issue

 

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