Texas rice producers are getting help with some of their most damaging insect and disease pests from Texas AgriLife Research efforts.

Researchers M.O. Way, X.G. Zhou, and Jo Young-Ki reported on efforts to improve pest control at the recent Texas Plant Protection Association annual conference in College Station.

Zhou said bacterial panicle blight (BPB) poses a serious threat to rice production across the Southern U.S. rice region.

“In 2010, the disease was widespread across the Texas Rice Belt and in Arkansas,” Zhou said. ‘Unfortunately, no effective chemical options are currently available.”

He said the disease caused yield reductions as high as 40 percent to 50 percent across much of the rice production area, including Texas, Louisiana, Arkansas and Florida. Milling quality was also reduced.

“This disease may be difficult to differentiate from other diseases,” he said, making it tricky to identify in the field. BPB appears to be exacerbated by high nighttime temperatures. Flowering time may be the most susceptible growth stage, and the pathogen may be either soil borne or seed borne.

No resistance

Growers also have no varietal resistance to help combat BPB, and that’s what Zhou and others hope to find with large-scale screening for variety resistance. They also are looking for biocontrol agents to help suppress BPB.

Zhou screened more than 60 varieties and elite lines from southern states in field trials at the Beaumont Research Center and at Eagle Lake.

“We found no varieties or lines completely immune to the disease,” Zhou reported. “Most of the varieties and lines, including CL111, CL 142-AR, CL 181-AR, CL 261, Cocodrie, Jazzman and Templeton were susceptible or highly susceptible. Jupiter, Neptune, Presidio, Rondo and the hybrids (XL 723, CLX 729, and CLX 745) were among the varieties showing partial resistance.”

He said the two bacterial biocontrol strains (Bacillus subtillis) most effective in suppressing BPB among more than 70 bacterial strains tested in the greenhouse were evaluated in artificially-inoculated field trials.

“Spraying rice panicles at flowering with either biocontrol strain reduced BPB severity by 41 percent to 50 percent and increased yield by 11 percent to 17 percent,” Zhou said. “Treatment with the antibiotic oxalinic acid was the most effective, reducing BPB by 86 percent and increasing yield by 21 percent. Integrated use of the bacterial biocontrol agents with partially resistant varieties may provide practical solutions to minimize the damage caused by BPB.”

  • Zhou recommended rice farmers follow some basic cultural practices to manage the disease.
  • Use partially resistant varieties.
  • Do not plant infected seeds.
  • Plant early to avoid late season high temperatures.
  • And avoid excess nitrogen rates.

 

New technology

M. O. Way said new technology is available to help manage some of rice producers’ most damaging insect pests.

“CruiserMaxx and Dermacor X-100 have Section 3 labels for rice,” Way said. “Nipsit INSIDE likely will have a Section 3 label on rice within two years. An EUP for Nipsit INSIDE was approved in Texas for 2011. All three new technologies are being evaluated in Texas for control of an array of pests including the rice water weevil, a key pest of rice in Texas.”

Way said a 2010 seeding rate study with Dermacor X-100 applied to Cocodrie seed at 1.75 fluid ounces per hundredweight with seeding rates of 60, 90 and 120 pounds per acre resulted in excellent rice water weevil control. “Yield increases were 888, 993, and 1,100 pounds per acre, respectively,” Way said.

He said Cruiser 5FS, “the insecticidal component of CruiserMaxx,” applied to Cocodrie seed at 3.3 fluid ounces per hundredweight, also provided excellent control of rice water weevil when seed was planted at 90 pounds per acre in the same study.

He said increased yield from the Cruiser 5FS treatment was 1,183 pounds per acre. A separate Nipsit INSIDE study, applied as a seed treatment to Cocodrie at 3.3 fluid ounces per hundredweight, “provided excellent control of rice water weevil with 1,048 pounds per acre yield advantage compared to untreated seed.”

Way said a long-horned grasshopper control study with Tenchu at 8 ounces per acre resulted in 95 percent mortality. “We’re working on a Section 18 for Tenchu,” he said.

Sheath blight

Young-Ki said proper cultural practices may not always provide acceptable control of sheath blight, the most common and most economically important disease in Texas rice production.

“Disease pressure can be alleviated to a certain level by integrating management practices including crop rotation and use of resistant varieties.” But that may not be enough to “guarantee yield protection from disease outbreaks under hot and humid conditions,” he said.

Fungicide application may be necessary to manage sheath blight in both the main and the ratoon crop, Young-Ki said.

He said a fungicide program study evaluated 12 treatments on Cocodrie rice. “Sheath blight was promoted with additional inoculation of Rhizoctonia solani.”

Results showed a tank mixture of strobilurin and trizole fungicide as the best control option in the main crop and with significantly less disease severity in the ratoon crop. Yield also increased.

“Disease severity in the main crop directly affected rice stand densities and yields in the ratoon crop,” Young-Ki said. “Keeping sheath blight at a low level on the main crop by appropriate use of fungicides is critical to successful ratoon crop production.”