“It was worth the cost to Doug and me,” Wilde says. Doug typically farms that field, and he lost money by keeping it in continuous cotton and setting part of it aside as a check plot. “That field has a lot of root rot,” John says.

Isakeit has a lot of time and energy invested in the project as well. “I started screening materials as a stem drench in 1999,” he says. He says little work had been done on cotton root rot since the 1980s after research projects ended at Texas A&M and in Arizona. “Our efforts really took off with Texas State support,” he says.

They started screening products on Wilde’s farm by applying them through subsurface irrigation tape. “For the first three years we found no positive results,” Isakeit says. “In 2008, we tried Topguard and were pleased to see it worked, but at very high rates.”

The real breakthrough, he says, came in 2010. “We applied the material at planting and at 1 pint to 2 pints per acre, and we had good response. We repeated that in 2011.”

Results last year, though disappointing at many locations because of severe drought—and no root rot infection—showed good response at locations away from San Angelo and gave them enough data to submit a request for the Section 18 exemption.

They also refined the application method last year. Instead of applying in the furrow at planting, which some research indicated could result in phytotoxicity, they applied Topguard through a T-band, which dispersed the material along the furrow wall. It’s that application method that’s labeled by EPA.

The label also calls for 1 pint to 2 pints per acre and no more than one application per year.

Minzenmayer says the product and application method “looks promising. We’ve learned a lot, but there’s still a lot to learn.”