Southern Plains and other Texas Blackland cotton growers could get a late Christmas present if EPA grants a Section 18 exemption for use of Topguard (flutriafol) for control of cotton root rot.

“It’s currently under review by EPA,” said Brent Jacobsen, technical manager for Cheminova, Inc., manufacturer of Topguard. “We expect to hear by late January.”

The proposed product use rate will be 16 to 32 ounces per acre, applied in a five-inch T-band behind the furrow opener and seed placement and before the furrow is closed. The T-band is safer than applying the material directly on the seed, Jacobsen said. A good portion of the material goes onto the furrow wall.

Research has shown that a simple in-furrow treatment may damage the seed, especially if planting is followed by significant rain or irrigation.

“But rainfall or irrigation is necessary to activate the fungicide,” Jacobsen said.

Flutriafol is a systemic fungicide but with some barrier activity, said Tom Isakeit, a Texas AgriLife Extension plant pathologist who has been screening materials to combat root rot since 2005.

“It has become a big project,” Isakeit said during the recent Texas Plant Protection Association annual conference in Bryan. “From 2006 through 2007, we saw no results,” he said. They tried applying the material through drip irrigation and found positive activity but at “extremely high rates. We knew it worked but we had to lower rates,” he said.

In 2009 he tried stem drench and drip irrigation. In 2010 they discovered significant disease reduction by in-furrow treatments. In 2011, they started seeking a Section 18 exemption from EPA.

It was not a good year to evaluate yield advantages. “We had a lot of crop failures due to lack of rainfall,” Isakeit said. “We need a rainy year to do testing.”

They did have a plot in Burleson County that showed a 20-percent yield advantage with Topguard. “A 20-percent yield bump is a magic number for the EPA,” Isakeit said. He also recorded fiber quality improvements. “We saw a slight increase in micronaire. It’s well known that root rot lowers mic. We also saw lower trash because we had fewer dead plants. Other fiber characteristics were not significantly affected.”

Isakeit and others tried numerous fungicides and application techniques before they identified what looks to be a viable control option for a disease that’s been a bane to Southern Plains cotton for more than a century. “We tried knifing in fungicide several times with no results,” Isakeit said.

Most of the counties that have identified root rot as a damaging problem for cotton will be covered by the Section 18, Isakeit said.

“In 2012, we will continue to work on fine-tuning the application process,” he said, “and wait for the Section 18.”

Further study

Jacobsen said Cheminova will continue to support efforts of Texas AgriLife Extension and the Texas Department of Agriculture to secure the exemption. “We also will look at T-band variations, the effect of irrigation timing, potential to apply pre-plant and try to get a better feel for moisture demand,” he said.

Isakeit said he’s hopeful that a problem that was identified as far back as 1872 may be near a solution. “In 1872, a farmer reported ‘poison soil,’” he said. “In 1888, a plant pathologist identified the fungus and a wide range of hosts. He recommended crop rotation.”

Crop rotation may provide some benefit but the fungus apparently remains in the soil and remains a threat to cotton production. Topguard may diminish that threat.