BATON ROUGE, La. – Louisiana rice farmers should be on the lookout for Mexican rice borers and stinkbugs, according to LSU AgCenter entomologist Mike Stout.
The Mexican rice borer was found in Louisiana in 2008 and is spreading, Stout said. Last year, it was found in Acadia Parish and this year, in Evangeline Parish. The borers have long been established in Texas, and as that population has built up, they have been moving eastward.
The borers lay eggs on rice plants, and the larvae bore into the plant. There they can feed on the stem but are protected from insecticide applications. They are difficult to scout for, and there is only a narrow window of time that insecticides are effective.
It's too early to tell how bad damage from borers in Louisiana will be this year, Stout said, but their growing geographic footprint is concerning.
"The big question right now is if the Mexican rice borer will be a major problem for us," Stout said. "It's been a problem for Texas rice farmers, but here in Louisiana we have similar borers that have been here for more than 100 years and don’t cause consistent problems."
Stout said DuPont's Dermacor seed treatment is effective in reducing problems with rice borers. For farmers that didn't plant seeds treated with Dermacor, the best thing they can do now is watch for damage, scout their fields and treat with a pyrethroid insecticide if they find rice borer adults, egg masses or larvae.
As the season progresses, stinkbugs will arrive. Stout recommends scouting fields with a sweep net once rice heads develop. There are a number of insecticides that effectively control stinkbugs.
The earlier part of this rice season saw increased numbers of fall armyworms compared to past years, Stout said. It's not clear why, and that increase is probably not a trend, he said.
The rice water weevil, another early-season pest that is consistently a major yield-reducer, emerged a little later this year because of the cold winter. The weevil population remained about the same as in previous years.
"The lesson is that you shouldn't be deceived if they're late," Stout said.
Similarly, Stout said he has seen fewer stinkbugs so far this year. They could be late or their population could be down, he said, but it is still important for farmers to be vigilant, scout their fields and take action if needed.