Posts Tagged: Rice

Monitoring armyworms in rice helps reduce damage

Armyworms can be a serious pest in rice. The worms can eat the rice foliate or panicles, and cause yield reductions.

In 2015, a severe outbreak of armyworms caught rice growers by surprise, resulting in yield losses. In a 2018 survey conducted by UC Cooperative Extension, rice growers reported average yield losses in 2015 ranging from 4% to 12%. Since UCCE began a monitoring program in 2016, rice losses to armyworms have been rare, according to Luis Espino, UC Cooperative Extension rice farming systems advisor in Butte and Glenn counties.

To safeguard the rice crop against the pests, UCCE began conducting areawide monitoring of armyworms in 2016 using pheromone traps that attract the moths as they fly around rice fields. The traps are set up in 15 locations of the Sacramento Valley, from Richvale to Knights Landing, and in three sites in the Delta, covering most of the rice production area of California. The traps were set up early in the season and checked weekly until fields are ready to harvest.

“Moth numbers are delivered to more than 1,500 growers and crop consultants weekly via email, so they have a warning system to know when populations are increasing and when to start scouting closely,” Espino said.

“Treatments are not always needed, but armyworm damage can occur quickly and monitoring needs to be increased during the periods of peak moth flight,” he said. During periods of peak flight, the UCCE advisors provide growers with information on how to decide if a treatment is needed.

The information from the armyworm monitoring network, together with efforts by the rice industry to register insecticides that are effective at controlling armyworms, has resulted in better control of armyworms and less yield losses.

“In 2017 and 2018, I'd say yield loss due to armyworms was rare, and probably only happened in a couple of cases,” Espino said. “It's hard to give you hard numbers, but I'd say in 2017 and 2018, yield losses have been reduced to a minimum.”

No need to be concerned about eating rice and rice products

A UC Cooperative Extension specialist says there isn’t enough scientific evidence to warrant consumers making changes to their diets nor to their children’s diets based on recent media reports about levels of arsenic in rice. The issue arose from an analysis by Consumer Reports of white and brown rice from around the world and rice products like rice cereal, rice milk and rice pasta.

“In virtually every (rice) product we tested, we found measurable amounts of total arsenic,” said the article.

However, Carl Winter, UC Cooperative Extension specialist in the Department of Nutrition at UC Davis, said it’s too early to recommend any changes in diet because of these findings.

“Arsenic is a naturally occurring element, found in a lot of different foods and some drinking water at different levels,” Winter said. “We’ve been consuming it all our lives. It’s too early to say whether it is causing any harm.”

He suggests people continue to eat a balanced diet that includes a wide variety of foods while the federal officials who are charged with protecting the United States’ food supply draw scientific conclusions about dietary arsenic exposure.

The U.S. Food and Drug Administration is currently collecting thousands of samples of rice-containing foods to develop a database that will allow the agency to establish acceptable levels in foods. Preliminary data released by the FDA in September found that the average levels of inorganic arsenic to be 3.5 to 6.7 micrograms per serving. The data collection is expected to be completed by the end of the year.

“The scientific approach is being taken right now to get a real handle on the typical level people consume,” Winter said. “Before you do that, it’s hard to say any population is at risk.”

Arsenic may be present in some other foods, but most crops don’t readily take up much arsenic from the ground. Rice is different because it is grown in flooded conditions. In an anaerobic environment, arsenic changes into a form that is easier for plants to absorb.

Swaying both ways

Imagine if rice – yes, that semiaquatic species that is typically cultivated under partially flooded conditions – could be both flood- and drought-tolerant. Such a rice variety would benefit rice growers and consumers worldwide and would be less vulnerable to weather extremes that may result from global climate change.

Now UC Riverside experiments demonstrate that such rice is already here. Genetics professor Julia Bailey-Serres’ research group reports in a recent issue of The Plant Cell that flood-tolerant rice is also better able to recover from drought.

“Flood tolerance does not reduce drought tolerance in these rice plants, and appears to even benefit them when they encounter drought,” Bailey-Serres says.

She and her team – Takeshi Fukao, a senior researcher, and Elaine Yeung, an undergraduate student – focused on Sub1A, a gene responsible for flood or “submergence” tolerance in rice. Sub1A works by making the plant dormant during submergence, allowing it to conserve energy until the floodwaters recede. Indeed, rice with the Sub1A gene can survive more than two weeks of complete submergence.

Plant breeders have already profited farmers worldwide – especially in South Asia – by having transferred Sub1A into high-yielding rice varieties without compromising these varieties’ desirable traits — such as high yield, good grain quality, and pest and disease resistance.

Bailey-Serres’s lab found that in addition to providing robust submergence tolerance, Sub1A aids survival of drought. The researchers report that at the molecular level Sub1A serves as a convergence point between submergence and drought response pathways, allowing rice plants to survive and re-grow after both weather extremes.

“Sub1A properly coordinates physiological and molecular responses to cellular water deficit when this deficit occurs independently, as in a time of drought, or following ‘desubmergence,’ which takes place when flood waters recede,” says Bailey-Serres who was the lead recipient of the 2008 USDA National Research Initiative Discovery Award.

Next, her colleagues at the International Rice Research Institute in the Philippines will test the Sub1A rice for drought tolerance in the field. What are some other implications of this research? One that comes to mind is that the “Got Rice?” slogan might have to drop the question mark, and put in its place a solid period!