‘Overtreatment’ Of Treated Seed Effective In Managing Water Weevils, Grape Colaspis In Rice
MARY HIGHTOWER
LONOKE, ARKANSAS
Arkansas’ rice growers need to be thinking not only about seed treatments, but also “overtreating,” or applying a second treatment to seed previously treated with another product, extension entomologists with the University of Arkansas System Division of Agriculture, said.
Planting has been underway for a few weeks in the nation’s largest rice-growing state and Nick Bateman, extension entomologist for the Division of Agriculture said seed treatments are key in the battle against two common foes: the grape colaspis beetle and the rice weevil. Both pests damage rice by feeding on the roots while in their larval stage.
“The majority of it is already treated with Cruiser, or a similar neonicotinoid, which does a great job on grape colaspis,” Bateman said. “The rice we’re putting in the ground right now and over in the next couple of weeks will probably take somewhere around 45 to 60 days to go to flood, but you’re looking at a residual on that product of 28 to 35 days, depending on the rainfall. It could be less than 28 if we get a lot of rainfall.”
Bateman suggests bolstering the effectiveness of Cruiser with one of two diamide insecticides.
“We’re going to be fine, from a grape colaspis standpoint, with those seed treatments, but from a water weevil standpoint, if we’re that late going to flood, we’re not going to have the residual there that we’d like to have to get good control of rice water weevils,” Bateman said. “We’ve been recommending trying to overtreat seed with Fortenza or Dermacor. They’re both diamides. They both perform very well on rice water weevil.
“That’s the problem with rice water weevil,” Bateman said. “It’s out of sight, out of mind. It’s below the soil surface. People see scarring on leaves and a few adults and don’t think much about it.
“But it doesn’t take a huge population of adults to lay enough eggs to have larval numbers over threshold and really start costing you money,” Bateman said.
“From all of the work we have done, we see that these products easily pay for themselves and protect bushels that we don’t realize we are losing,” he said.
Arkansas research on seed treatments in rice can be found in the fact sheet “Rice Insecticide Seed Treatments: Is there Value to the Arkansas Rice Producer?”
The Arkansas Rice Production Handbook also has a chapter dedicated to insect management. ∆
MARY HIGHTOWER: University of Arkansas