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Posted 27 May 2014. PMN Crop News.

Rice Farmers Need to Watch for Weevils With Warmer Weather

Source: Louisiana State University Press Release.

Mamou, Louisiana (May 23, 2014)--Rice farmers should be prepared to deal with their worst insect pest, the rice water weevil, according to LSU AgCenter entomologist Mike Stout, speaking at the Evangeline Parish Rice Tour on May 22.


Stout said many fields are being flooded, and that is the trigger for weevils to start laying eggs on the young rice plants. After hatching, the weevil larvae then feed on the rice plant roots.

Stout said the cold winter and spring delayed the weevil emergence, but they have appeared as the temperatures have risen. “They’re out in good numbers now,” he said.

He said many farmers use seed treatments such as Dermacor and Cruiser, which prevent larvae from feeding on a plant roots. Insecticides can be sprayed to combat the insect, too.

Stout said plants seem to have secondary benefits from seed treatments that aren’t easily explained. For example, a seed treatment of Cruiser may result in improved cold tolerance. “When you put Cruiser on rice seed, it seems to pop out of the ground faster.”

Stout said research is being conducted to see if seed treatments will help plants endure herbicide damage.

He is also conducting research to determine if fungi colonized in a rice plant’s roots could result in more damage from insects.

Dustin Harrell, LSU AgCenter agronomist, said research is ongoing to update optimum fertilizer rates.

He showed farmers a test plot near Mamou where current rates are being tested. He said a test last year at the same field showed that the optimum rate for potassium was 90 pounds per acre, 30 pounds more than the current rate recommended by the LSU AgCenter.

Eric Webster, LSU AgCenter weed scientist, said a new chemical on the market, Sharpen, works well but crop injury will increase slightly if it is mixed with post-emergence herbicides.

Webster said he is working on a new herbicide, Provisia, from BASF that will be used on a new herbicide-resistant rice. “It’s got a lot of promise,” he said.

Steve Linscombe, LSU AgCenter rice breeder, said he is testing several crosses of rice in the development of a unique rice variety to be used with Provisia. He said seed brought back from the winter nursery in Puerto Rico is being planted for further testing, and several lines have potential.

Linscombe said his breeding program depends heavily on funding from the rice checkoff program. Farmers have paid 5 cents, dedicated to research, and 3 cents for promotion, for every 100 pounds of rice sold. A legal challenge to the checkoff program resulted in a new checkoff program approved by the Louisiana Legislature and now being considered by the governor.

“It’s extremely valuable to the industry,” Linscombe said. He credited Evangeline Parish farmer Richard Fontenot for his efforts working with the Legislature for getting the checkoff legislation passed.

Johnny Saichuk, LSU AgCenter rice specialist, said his verification program would not exist without the checkoff funding.

Saichuk said this rice crop is behind schedule. But, he said, the crop has improved with clear skies that brought ample sunlight. “I call this the season in slow motion,” he said.

Don Groth, LSU AgCenter plant pathologist, said last winter’s cold weather killed rice plants, eliminating possible hosts for diseases. The recent dry weather also will discourage disease outbreaks, he said.

Groth said the range of fungicide-resistant sheath blight continues to expand. He said the disease can be countered with the fungicide Sercadis. This year, he said, Sercadis will be cheaper, and it has a full label making it available for use everywhere.

He said another fungicide, Convoy, is an alternative material, but it not as effective as Sercadis.

Julien Beuzelin, LSU AgCenter entomologist, said the Mexican rice borer continues to move eastward. Last year, he said, it was found in Vermilion, Acadia and Allen parishes. “We expect them to be in your area this year,” he said.

But, he said, the effects of the borer could be minimal, and Dermacor seed treatment appears to provide protection.

Farmers and crop consultants saw a demonstration of an unmanned aerial vehicle, or drone, by Randy Price, LSU AgCenter agricultural engineer. Price said the devices can be used to scout fields, although the Federal Aviation Administration restricts their use for commercial purposes.