John Wilde looked over a field of cotton near his San Angelo, Texas, farm and noted the differences between several test plots on one side of a field road. Some plots looked healthy with potential to make exceptional yields; others showed large areas of dead cotton stalks and poor yield prospects.

He looked to the other side of that narrow path, where no trials have been applied, and figured yield loss will be 50 percent or higher.

Wilde and his son Doug have turned this cotton patch over to Texas AgriLife Research and Extension scientists who are using it to test control options for cotton root rot, a devastating disease that costs Southern Rolling Plains farmers thousands of dollars every year.

“This is a root rot nursery,” Wilde says. “Usually, we would rotate this field out of cotton to corn to manage root rot, but we know that it’s a good place to test control options.” He says the sacrifice will be worth the trouble if scientists find a viable control for root rot.

They may be close. After testing several fungicides through subsurface drip irrigation injection for several years, Extension IPM specialist Rick Minzenmayer and Extension plant pathologist Tom Isakeit discovered that flutriafol, a fungicide labeled only for soybeans and apples, will control the fungus that causes root rot. (Early results were reported in a Farm Press article last December.)

Yield advantage

David Drake, an Extension agronomist who came on board at the San Angelo Research and Extension Center last year, says yield results from 2009 tests indicate as much as a 500-pound per acre yield advantage in flutriafol treated plots.Although the best results came from high rates, lower rates similar to labeled rates on other crops also reduced disease and gave a yield increase.

In 2010 trials, the research emphasis was on evaluating lower rates with different application methods and in different production areas of Texas. Results from these trials in the San Angelo area and other areas of Texas were mostly encouraging. The data will be used to support a label for this fungicide on cotton further down the road.

A key sticking point to getting an EPA label may be residual activity. The product appears to persist in the soil from one year to the next. Plots treated one year in Wilde’s field and untreated the next continue to show good control.  However, persistence of a chemical in soil is not a good characteristic in the eyes of the EPA.

Drake says that flutriafol is a “pretty stable product,” and stays where it’s applied. Leaching potential is uncertain. “It does not appear that the product moves, but we’re still looking. We need to determine the best rate, have the residue work done, and then get a label.”

This year has been a bad one for root rot throughout the Rolling Plains. “Throughout the Rolling Plains and into the Blacklands, we’ve seen perhaps a 20 percent crop loss from root rot,” Drake says. “Heavy July rainfall seemed to encourage it.”