Screening for disease gets earlier start in rice breeding

Frances Gould  |  5/31/2016 3:19:44 PM

Don Groth, LSU AgCenter plant pathologist, assists the breeding program by screening potential varieties for disease resistance and susceptibility.

“We screen thousands of lines every year for the breeding project,” Groth said.

He said an emphasis has been made to screen earlier generations for sheath blight, bacterial panicle blight and blast.

Screening had been conducted with the fifth generation after a cross, but “we realized we needed to go further back,” Groth said. So now, the screening process can start as early the third generation after a cross.

Groth said disease resistance has gotten stronger in the breeding program at the Rice Research Station.

Susceptibility ratings for sheath blight were on the very susceptible and susceptible end of the rating system, he said, but that has been reduced. “We’ve got a lot more resistance and moderately resistance lines in the germplasm.”

That improvement is showing up in commercial fields where sheath blight is not as much of a problem as it was in previous years.

“My hope is we can eliminate the very susceptible and susceptible lines in the program,” Groth said. “That’s my aim – to give farmers varieties that don’t need fungicides as often.”

He said it’s not likely that a variety could be developed that would be completely disease resistant because yield and quality would be reduced.

“If a plant is completely resistant, it’s got to take some of its photosynthesis material and use it for that resistance,” he explained. “It’s a fine line, but we’re finding combinations that have high yield and disease resistance.”

He said sheath blight wasn’t as big a problem for some farmers who opted not to spray fungicides, saving $30-40 an acre.

Groth said he is concerned that chemical companies are not investing as much in new materials to fight disease. He said only one fungicide class, strobilurins, is used for blast, but he would prefer to have more than one mode of action against the disease.

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