Scout Now To Manage Sheath Blight In Rice

SARA CATO 

LITTLE ROCK , ARKANSAS

As Arkansas rice fields move into reproductive stages, specialists with the University of Arkansas System Division of Agriculture are advising producers to scout for sheath blight, especially as frequent rain can accelerate its growth.

Sheath blight, a disease caused by the fungus Rhizoctonia solani, is prevalent in Arkansas rice fields. It causes long, oval, purple-bordered lesions and bands of dying tissue in the leaf blades. Symptoms are typically seen as rice moves into reproductive stages. Jarrod Hardke, extension rice agronomist for the Division of Agriculture, said scouting and potential fungicide applications are recommended to avoid yield loss.

“While sheath blight presence has been increasing, it is only just starting to take off up in the canopy in some fields,” Hardke said. “Rains this week and over the weekend may aggravate it and make it more aggressive, so be on the lookout.”

Hardke noted that some fields may be out of the danger zone for sheath blight. “There are some fields making it to heading with sheath blight still low, meaning we’ve outrun yield loss,” he said.  

Camila Nicolli, extension plant pathologist for the Division of Agriculture, said scouting is key to mitigating impact.

“One of the primary reasons scouting for disease is crucial is that early detection of symptoms allows for quick action. Especially for sheath blight, that requires opening the canopy to check,” Nicolli said. “The goal is to identify sheath blight at its initial stages before it begins to progress. Then we can monitor progress to determine if treatment is warranted.”

Scouting rice for sheath blight involves checking in a zigzag pattern, stopping every 50 steps and inspecting 3-foot-long sections for symptoms. If symptoms are present, the stop is a “positive stop.” Division of Agriculture specialists recommend fungicide applications at 35 to 50 percent positive stops, depending on which variety of rice is planted.

Find recommendations for sheath blight management in the 2023 Rice Management Guide. Read more about current Arkansas rice conditions in the latest Arkansas Rice Update.   ∆

SARA CATO: University of Arkansas