Rice blast under attack in nursery

Every year, University of Arkansas Division of Agriculture scientists are intentionally infecting 10 acres of rice with blast.

The infections take place in a blast nursery developed over the last four years at the Pine Tree Branch Experiment Station near Colt, Ark. UA plant pathologist Fleet Lee said the nursery is ideally suited to screen new rice breeding lines for resistance to blast.

“In the past, we had limited space in several research stations scattered around the state that restricted our capacity for screening,” Lee said. “This new nursery enhances our ability to evaluate germplasm for blast resistance.”

He said the project began four years ago when the Arkansas Rice Research and Promotion Board allocated funds to build the nursery at Pine Tree. Roger Eason, resident director of the Pine Tree Branch Station, began clearing and leveling a 10-acre field bordered by woods that serve as a wind break. Corn is grown for a wind break on the sides not protected by trees.

A sprinkler system with large nozzles, each of which can cover a 300-foot diameter, was installed and used for the first time this year.

“The sprinklers provide an artificial rain that spreads the fungus that causes blast,” Lee said. “They worked great and we had good blast development.”

The new nursery is already assisting breeders with both conventional breeding lines and those produced through genetic modification. “Karen Moldenhauer (UA rice breeder) has some advanced breeding lines in the nursery that are showing good resistance to the types of blast we see in the United States,” Lee said. “It helped (breeder) James Gibbons eliminate some lines that proved susceptible to blast, helping him to narrow his search for resistant plants.”

The nursery also provides an area to evaluate fungicides.

“Eventually, diseases adapt to a point where they can infect varieties that previously were resistant,” Lee said. “We're studying some potential new fungicides that will be effective against blast when this occurs.”

He said other diseases can be evaluated in the nursery as long as they don't compromise the blast research.

“The main objective is to provide continual information, comparing how different lines react to blast as breeders move their research forward,” he said. “And we can evaluate new rice germplasm from different sources to determine if it has resistance that can be used to develop new breeding lines.”

Fred Miller is science editor for the Arkansas Agricultural Experiment Station. e-mail: [email protected].

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