By John Cartwright
With the discovery of overwintering blast next door in Louisiana, Arkansas rice growers should scout their fields early in the season to nip any potential infections in the bud, said Yeshi Wamishe, Extension plant pathologist for the University of Arkansas System Division of Agriculture.
A Louisiana plant pathologist issued a February report warning of blast lesions on new rice sprouts growing from stubble. Dr. Don Groth of LSU AgCenter said that the warm, moist winter has encouraged the blast fungus to make spores.
“Louisiana had a severe blast epidemic in 2012,” says Wamishe. “There is fear that another blast outbreak may happen earlier in the season in 2013.”
It is probable that the blast survived in “volunteer” rice plants that were not freeze-killed.
Blowing In The Wind
Blast does have the ability to move – on seeds and by wind. The fungus could find safe harbor in rice seeds that are transported over state lines, said Wamishe, adding that although Louisiana and Arkansas share varieties, they are generally blast-resistant ones. She also warns that winds, like the ones that accompanied the remnants of Hurricane Isaac last year, could blow the blast over hundreds of miles, which could easily impact fields in Arkansas.
Despite this, Arkansas avoided a broad infection epidemic last year. Only a few small infections, in Lonoke and Monroe Counties, appeared. One field that did see a large area of infection was mitigated by proper flooding and fungicide application and another saw damage due to its heavy tree lines, which prolonged the nighttime dew period that incubates and feeds the fungus.
Best Management Practices
Wamishe is familiar with the rice blast fungus and offers Arkansas farmers the following pointers for avoiding and mitigating this dangerous pathogen.
• Producers should plant blast-resistant rice varieties. If they cannot, preventive fungicide should be applied at the appropriate labeled rate.
• High nitrogen levels, which can make susceptible varieties even more vulnerable, should be avoided by also applying at the recommended rate.
• Maintaining a four-inch flood on the field will keep all varieties healthier.
• Sow the rice in fields with light tree lines. Heavy tree stands can keep morning dew on the field for a longer period of time, which helps grow the fungus.
• Planting over an early planting window is a good way to shield rice from the blast. Staggered planting allows for easier detection of the blast.
• Scout fields early in the season. Early detection allows for proper fungicide application; fungicide should be applied first at the late boot stage, and then again at the late heading stage.
John Cartwright is an independent journalist writing for the University of Arkansas Division of Agriculture.