Application Technology for Injecting Telone

Current reductions of methyl bromide and the eventual loss of the gas fumigant in 2005 have prompted a lot of research in a relatively short period of time. Researchers have conducted numerous studies to find a chemical or chemical combination to replace methyl bromide. In the meantime, some researchers are exploring new ways to use existing chemical fumigants.

Telone is an effective fumigant against nematodes and soilborne disease and, when combined with an herbicide, it can approximate the control of methyl bromide. However, regulations that govern personal protection equipment and buffer zones make its use prohibitive for some.

John Mirusso, fumigation consultant to Dow AgroSciences, developed a piece of farm equipment that injects Telone into the soil and slows its escape. Mirusso contacted Yetter Farm Equipment of Illinois 2 years ago to discuss modifications to a coulter assembly to accommodate soil injections of Telone. "John told us he needed a piece of equipment that could handle field residues from previous crops and inject a fumigant to a depth of 12 inches, with minimal soil disturbance," recounts Mark Seipel, regional sales manager for Yetter.

Yetter, a 71-year-old business, focuses mostly on equipment for use in the Corn Belt. Seipel says, "Our equipment, historically, is used for conservation tillage and fertilizer placement, but grower needs are changing. Telone injection is a new avenue we are pursuing due to the methyl bromide phaseout. The market is changing so changes in technology and application are needed."

The new 2986 coulter 30-inch Avenger, took several months of development by Mirusso, the Yetter company, and Jerry Nance, Dow AgroSciences' Telone specialist. "It features, as indicated in its name, a 30-inch coulter that allows for fumigant application up to 12 inches, as compared to 6 inches with a standard Yetter coulter," says weed scientist James Gilreath of the University of Florida's Gulf Coast Research and Education Center, Bradenton.

"We looked at a lot of equipment before settling on the 2986 coulter 30-inch Avenger," says Nance. "The emissions are very low, so using the rig makes fumigating the field a one-person job. This significantly affects growers, who must use personal protection equipment when fumigating."

Sealing devices were added to the knives that follow the coulter. The knife has a tube in the back side that delivers the fumigant to the bottom of the groove. The beaver tail is angled so it compacts or presses a bit of soil about 3 inches from the bottom of the chisel groove. "This keeps the fumigant from moving rapidly up the groove and dissipating into the atmosphere," explains Gilreath.

Following each coulter assembly is a set of press wheels that presses the soil surface to seal the knife and coulter groove at the surface. The amount of force applied to them is adjustable.

"One can use chisels without the coulter," Gilreath says. But he cautions, "If there is tying string or plastic mulch residue in the soil, it gets hung up on the chisels and can be dragged around. This results in chisel grooves substantially larger than the chisel itself, and this allows rapid outgassing of fumigant."

According to Nance, this is definitely not what a grower wants. "You want the chemical in the ground to do its job and then degrade. What escapes is unused and useless product."

It also contributes to air emissions that can affect the size of buffer zones. "Air emissions are measured to help determine buffer zones. If the fumigant does not escape into the air, then neighbors are not exposed to the fumigant," says Peter Caulkins, associate director of EPA's Registration Division.

So far, the amount of outgassing is low, according to Mirusso. "The numbers look great and the Telone is expanding out at the depth of injection, which increases effectiveness."

These types of innovative collaborations will have to continue to adjust to life without methyl bromide. "Agriculture is going through tremendous changes now and modifications are necessary. The best products are made with input from our consumers—the farmers," says Seipel.

Last Updated: March 22, 2001