Agribusiness: Hybrids hold firm in tough disease year

LITTLE ROCK, Ark. – Mother Nature created ideal conditions for plant diseases to thrive this summer, plaguing rice in coastal Texas and Louisiana and across the Mid-South, but hybrids appear to have held their ground.

“This year has had the most disease potential of any year since I have been back in Arkansas, which is about 12 years,” says Rick Cartwright, plant pathologist with the University of Arkansas Cooperative Extension Service.

One of the wettest Junes on record was ushered in by heavy rains in late May. The southeast and central parts of the state received deluge after deluge of rain, and conditions were hot and humid. Rainfall, heat and humidity continued into July for much of northeastern Arkansas. The result has been ideal conditions for the two most deadly diseases for Mid-South rice crops: sheath blight and leaf blast.

The University of Arkansas estimates 800,000 to 1 million acres of rice were treated for diseases this summer. Cartwright says up to 400,000 acres of rice has been identified as having leaf blast symptoms, and at least 600,000 to 700,000 acres would be treated with fungicides for sheath blight control.

“Part of the problem is that a lot of the varieties we plant are somewhat susceptible to blast,” Cartwright explains. “Our most popular cultivar is Wells, a variety that is somewhat susceptible to blast. Clearfield 161 was planted on a lot of acres in Arkansas this year as well, and it is somewhat susceptible to blast and very susceptible to sheath blight.”

Even in a year of such heavy disease pressure, the vast majority of acres planted with RiceTec hybrid rice did not require costly fungicide applications.

“In our experience, the hybrid rice, if managed according to RiceTec’s guidelines for management, does not get much disease pressure,” says Dr. Cartwright.

The common races of blast found in the United States should not be a problem in any of the commercial hybrids from RiceTec, says Van McNeely, technical services manager for RiceTec. McNeely is based in Jonesboro, Ark., and says there have been no reports of blast on any of the RiceTec hybrids this year in Missouri, Arkansas, Mississippi and northeast Louisiana.

“We have had some Clearfield XL8 sprayed for sheath blight, but a very small percentage compared to the rice varieties, which have been pounded by both leaf blast and sheath blight,” he says.

RiceTec hybrids have excellent disease ratings from researchers at the major universities. The three primary RiceTec hybrids available for planting - Clearfield XL8, XP710 and XP712 - have the best available overall disease package, and in most cases, should not require a fungicide application.

XP710 has demonstrated an even better tolerance for sheath blight than Clearfield XL8, says McNeely.

“Our rating and university ratings on sheath blight for XP710 are far better than anything else on the market,” he says. “The tolerance to major rice diseases our hybrids offer can be a major risk-management tool for producers.”

South of Kaplan, La., planting rice near the Intracoastal Waterway means dealing with heavy disease pressure most every year. Ernest Girouard says very seldom does a year go by that he does not have to make at least one fungicide application on his rice. For the past two years, he has been growing hybrids in side-by-side strip trials with the conventional varieties he normally plants.

“This year, which was a worse disease year than most, I did not have to spray the hybrids,” he says. “Our main pressure is from sheath blight, and we find that the disease not only affects yield, but it also affects milling and the ratoon crop. In our trials with RiceTec, we have not applied fungicides on the hybrids, and the yields and milling were better than my conventional rice.”

All of Girouard’s conventional rice had a fungicide application this summer. Although a small number of individual hybrid plants appeared to have sheath blight symptoms, the disease did not seem to affect the overall strip trial, so no hybrids were sprayed, he says.

“In spite of having a little disease pressure, the hybrids still yield and mill much better than my conventional varieties,” says Girouard. “There can be disease all around it in the fields, and in some cases, disease actually on some hybrid plants, but we still get excellent yields. I am very interested in what I am seeing with the hybrids from RiceTec.”

Like the Mid-South, coastal Louisiana and Texas experienced similar wet, humid conditions ideal for rice diseases, says Mark Spilman, technical services representative for Texas and south Louisiana at RiceTec.

“This has not been a favorable year for rice production due to disease pressure,” Spilman says. “A lot of the rice was sprayed at least once for sheath blight, but generally speaking, very few of the hybrids required a fungicide application, and disease pressure has been significantly worse in coastal Louisiana and Texas this year.”

RiceTec, Inc. headquartered in Alvin, Texas, was the first company to commercialize hybrid rice seed in the United States. For more information, visit the company’s website at

e-mail: [email protected]

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