Mexican rice borer continues its move into Louisiana

The Mexican rice borer continues to expand its territory in Louisiana after migrating from Texas.

An adult Mexican rice borer was found recently in a monitoring trap in southeast Beauregard Parish just a few miles north of the Calcasieu Parish line, according to Tad Hardy, Louisiana Department of Agriculture and Forestry entomologist.

He revealed the discovery Sept. 14 at an LSU AgCenter meeting for county agents and crop consultants to discuss the best ways to treat the insect. Hardy said the trap was not located in a crop field.

"It is possible it will be a serious pest problem for us," said LSU AgCenter entomologist Natalie Hummel.

Based on the insect's past movement of 15 miles per year, Hummel estimated it could be in the heart of Louisiana rice country in two years. She said it's likely it will be more of a problem in sugarcane than rice.

Stubble management is important to deprive the insect of potential over wintering vegetation. She said that could be done by cutting rice lower with combines, mowing or plowing stubble, or establishing crawfish ponds on rice fields.

Mowing ditch banks and field edges could also make a field less attractive for borers, she said.

The pest was first found in Louisiana in 2008 in Calcasieu Parish near Vinton, and it was found late last year on the eastern edge of Calcasieu Parish. But have been found in traps in neighboring Jefferson Davis Parish.

The borer has been a pest in Texas rice since 1988, said Texas A&M entomologist Mo Way. "We've been able to manage it over the years."

Some rice varieties are more susceptible than others, Way said. Natural hosts for the insect include several weeds, such as Johnsongrass, sprangletop and vaseygrass. It could be the insect has thrived in Texas because of the large amount of fallow ground and pastureland there.

Texas A&M benefits from work by LSU AgCenter researchers on the insect, Way said. "We rely on the LSU AgCenter for a lot of our work in Texas."

Chemical control has involved spraying a pyrethroid insecticide at the 1-inch to 2-inch panicle stage, followed by an application at late boot or early heading that can be tank-mixed with a fungicide.

It's likely that the insect can be controlled in Louisiana rice, said LSU AgCenter entomologist Mike Stout. "I'm hopeful we're not going to have big problems."

The sugarcane borer, an insect similar to the Mexican rice borer, has not been as much of a problem in Louisiana as it is in Texas, Stout said. "That suggests there is some difference between the states."

Monitoring traps maintained by the Louisiana Department of Agriculture and Forestry have given Louisiana advance warning that the insect has arrived in the state, he said. Continued scouting, destroying overwintering sites, and aggressive treatment with pyrethroids and Dermacor seed treatment could keep the insect in check.

"We at least ought to try to slow the spread," Stout said. "We're in a unique position because we've caught it early."