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Posts Tagged: rice

A report from the war on weeds

Over the last three millennia, the practice of growing rice has evolved and spread throughout much of the globe. From China, through India, to Greece and parts of the Mediterranean and from Europe to the Americas, rice has demonstrated its versatility in desert regions and wetland deltas alike. Abundant in carbohydrates, it is today one of the world’s most widely eaten foods.

While University of California researchers develop rice varieties more tolerant to the modern challenges of climate change — flooding, heat stress, drought — California rice farmers each year discover more new threats in the form of non-native and herbicide-resistant weeds. So well adapted are these weeds that if left unmanaged, they cause rice yields in some places to plummet to nearly nothing.

Doctoral student Whitney Brim-DeForest researches invasive rice weeds. (Photo: Brad Hooker)

The introduction of rice to California in 1912 was fraught with weed challenges from the start. The traditional dry-seeding method allowed barnyard grass to quickly overrun fields. While a new water-seeding technique suppressed the weed, it led to a whole other set of problems. In continuously flooded fields — still the most widely used practice in California today — an imported weed, late watergrass, flourished. Aquatic weeds took advantage of the new environment while others gradually became more flood tolerant. For many years, advanced herbicides allowed farmers to gain ground over these weeds.

Then, beginning in the early 1990s, several weed species, including late watergrass, were found to be evolving resistance against the most powerful herbicides. A metabolic resistance to one herbicide, researchers discovered, could lead to resistance for another.

Weeds also found new ways to outcompete rice. One invasive weed, Ludwigia, grows fast and tall — as high as 10 feet. Shadowing the rice plants, it spawns tiny seeds that travel well in water. Other weeds, meanwhile, are small and run along the ground to avoid combines and some emerge earlier in the season than rice, dominating resources.

In the Department of Plant Sciences at UC Davis, professor Albert Fischer’s laboratory is battling rice weeds on a variety of fronts: by researching the evolution and mechanisms of herbicide resistance, finding traits that make rice varieties more competitive, developing resistance techniques through field testing at the industry-supported Rice Experiment Station in Biggs, Calif., and by encouraging farmers to diversify management methods.

UC Davis Professor Albert Fischer and his team are researching the evolution of herbicide resistance. (Photo: Brad Hooker)
“Use as many little hammers as you can on your weeds,” advises Whitney Brim-DeForest, a doctoral student at the University of California, Davis, in reference to the established ecology text “Many Little Hammers.” She instructs growers and is currently running Fischer’s field trials. “Don’t use just one tool year in, year out,” she says, “because you’re applying evolutionary pressures to the weeds.”

One system Fischer encourages is the stale seedbed technique, which allows weeds to emerge first from a reserve of seeds in the soil. Once that flush is up, farmers use a general herbicide to kill the weeds. At least one local farmer with a bad weed problem has controlled late watergrass this way. By replacing herbicides with shallow tilling, organic farmers can use this method.

With each management system is a different combination of growing techniques and herbicides, depending on weather, soil moisture and soil temperature, among other factors. Fischer’s team at the experiment station spends much of its time testing these herbicides on new weeds.

UC Cooperative Extension farm advisors encourage growers to also sanitize equipment, rotate crops, scout for surviving weeds and apply herbicide only when necessary, easing selection pressure on weeds while reducing environmental impact. Along that line, Fischer’s team is discovering how switching growing techniques and irrigation systems may be helping farmers meet higher environmental standards, addressing a trend of steeper water prices in California. Other researchers see this as an opportunity to reduce greenhouse gases released from decaying rice stalks post-harvest.

For each strategy, researchers weigh costs over benefits to select the right weapons for arming farmers entangled in this ongoing war with weeds.

Posted on Wednesday, February 5, 2014 at 9:13 AM
  • Author: Brad Hooker
Tags: Albert Fischer (2), late watergrass. (1), Plant Sciences (2), Rice (16), Weeds (24)

Rice planting on schedule in Butte and Glenn counties

Despite light rain earlier this week, it appears the Butte and Glenn county rice industry is getting seeds in the ground during the ideal planting window, reported the Chico Enterprise Record.

The ideal time for planting rice is May 1-15, said Randall "Cass" Mutters, UC Cooperative Extension advisor in Butte County. As the date gets later, farmers will end up with a later harvest. Fall weather is more unpredictable and farmers could end up harvesting in the mud. Last year, farmers were still planting rice at the end of May.

"I would say overall (this year) we're between a week or two weeks ahead of schedule," Mutters said.

Rice planting is on track in 2013.
Rice planting is on track in 2013.

Posted on Thursday, May 9, 2013 at 9:41 AM
Tags: Cass Mutters (7), rice (16)

New information on IPM in rice available from UC

Rice manuel
The third edition of Integrated Pest Management for Rice is now available. The publication's informative color photographs of pests and their damage, line drawings, tables, and figures are valuable aids in the diagnosis and treatment of common rice pests. 

New in this edition, readers will find information on:

  • Exotic pests in rice
  • Detecting, confirming and managing herbicide resistance
  • New diseases:  bakanae, rice blast and false smut
  • New weeds: red rice, rice cutgrass, waterstargrass and Monochoria

The publication also has:

  • Illustrations now in color
  • Life cycle illustrations for each disease

Integrated Pest Management for Rice is UC IPM principal editor Larry Strand’s last work before he retired. The book was written with the help of University of California researchers, Cooperative Extension specialists and farm advisors. The committee of technical editors includes Luis Espino, UCCE advisor in Colusa County; Albert Fischer, professor in the Department of Plant Sciences at UC Davis; Larry Godfrey, UCCE specialist in the Department of Entomology at UC Davis; Christopher Greer, UCCE advisor in Sutter, Yuba and Colusa counties; James Hill, UCCE specialist in the Department of Plant Sciences at UC Davis; Rex Marsh; UCCE specialist emeritus in the Department of Wildlife, Fish and Conservation Biology at UC Davis; and Randall (Cass) Mutters, UCCE advisor in Butte County.

IPM for Rice is available for $27 online in the UC ANR Catalog (, and in person at many UC Cooperative Extension county offices.  More information, including a view of the table of contents, are on the UC IPM website.

The California rice crop was valued at $850 million in 2011, according to the CDFA crop report.
The California rice crop was valued at $850 million in 2011, according to the CDFA crop report.

Posted on Wednesday, February 20, 2013 at 11:21 AM
Tags: IPM (38), rice (16)

UCCE advisor reports on last September's mysterious rice slow down

When the calendar said it was time to harvest rice last September, the crop wasn't ready. Over the winter, UC Cooperative Extension advisor Randall "Cass" Mutters tried to solve the mystery of the untimely immature rice, reported the Oroville Mercury-Register.

Since the problem was ubiquitous in the Sacramento Valley, Mutters deduced the weather was the culprit. He crunched weather numbers, studying humidity, nighttime and daytime temperatures, and uncovered a plausible explanation.

Average temperatures were comparable to 2009, when rice growers enjoyed a bumper crop. But from Aug. 24 to Sept. 12, he said, there were 18 days in a row where nighttime temperatures fell below 55 degrees. The cold nights likely delayed the crop's maturity.

Reporter Heather Hacking also wrote in her story about a another presentation at the annual Rice Growers Meeting in Richvale, in which UCCE advisor Chris Greer commented on recent media attention about arsenic in rice and rice products.

Sutter Buttes is in the distance behind this Colusa County rice crop.
Sutter Buttes is in the distance behind this Colusa County rice crop.

Posted on Tuesday, January 29, 2013 at 12:12 PM
Tags: rice (16)

California rice growers reduce greenhouse gas emissions

Rice contributes about a tenth of 1 percent of the GHG emissions from California’s agriculture sector.
California rice grower Tom Butler is dry seeding his crop to reduce irrigation and draining the fields earlier than before when preparing for harvest. These new practices conserve water and may help the environment by reducing greenhouse gas emissions from his farm, according to an article by UC Davis science writer Brad Hooker. The story was picked up by Western Farm Press.

Butler is participating in a pilot program funded by the Environmental Defense Fund. Though it’s too early to measure, he has seen promising signs from the project.

“We’ve had good results with yield and water conservation, which really was our goal,” says Butler. “We’re happy that greenhouse gases go down as a result of that, but they weren’t the initial reason why we do that.”

Of the global GHG accumulation for all sectors, 0.001 percent comes from California rice fields, according to data compiled by Luis Espino, UC Cooperative Extension rice farm advisor for Colusa County.

“It’s such a new issue I don’t think much has been done in that area,” says Espino. “Right now UC Davis is doing the research, doing the modeling, trying to understand what goes on in the soil.”

Cass Mutters, UC Cooperative Extension advisor for Butte County, noted that California rice growers realize that being environmentally sensitive is part of their responsibility. Since the 1980s, changes in irrigation management and other practices have led to a 98 percent reduction in pesticide residues entering public waterways from rice fields. Along with water quality, the rice industry supports an air quality monitoring network that enables the Air Resources Board to model how many acres can be burned without exceeding federal air quality standards.

Posted on Monday, January 7, 2013 at 2:40 PM

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