Cooperative Extension San Joaquin County
University of California
Cooperative Extension San Joaquin County

Posts Tagged: Plant Sciences

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

Votes needed for UC Davis teams in international food challenge

World population is expected to reach 9 billion by 2050. (Photo: UN Human Development Report)
With the world population reaching 9 billion by 2050, creative solutions are needed for global food security. The 2013 Thought for Food Challenge has put the call out and two UC Davis teams have responded. One group, Team UC Davis, proposes a social networking game that spreads awareness through crowd sourcing and draws donations through virtual purchases.

“The team is using a game platform like Farmville, which they call Global Village,” said Patrick Brown, professor in the Department of Plant Sciences at UC Davis, the team’s mentor, in comparing the proposal to the popular social networking game. “The difference is that the settings for Global Village are realistic and representative of developing world farm settings, the game has a strong educational function and the profits from the game and purchases within the game go to fund development activities.”

Team UC Davis is made up of undergraduate and graduate students from International Agricultural Development and the Department of Plant Sciences. Their idea is to create a game application for the Facebook social media network. Players are given information and choices for farming based on real-world information gathered from developing countries, such as from a cacao orchard in Cote d’Ivoire or a maize farm in Zambia. Based on the limited resources of these farmers, they deal with issues like diseases, soil types, crop planting, where to deliver fertilizers and more.

The purchases they make in the game for virtual items like chickens or fertilizer lead to real purchases for the farmers. Partnerships with corporations like Grameen-Intel and Mars will provide the game with the real-time data those companies have gathered on current projects, while global nonprofit organizations like Heifer International will help transform the virtual purchases into real items for the farmers. The hope is to educate game players about these regions and existing farming issues, while raising donations and promoting corporate responsibility.

For the proposal to become reality, Team UC Davis must get enough votes to pass to Round 2. A total of five teams will be selected to present their business plan in Berlin, Germany, in September. Prizes include grants up to $10,000.

Voting takes place online from now to May 10. At the top of the Thought for Food page supporters can click “Like” for their favorite team. These “likes” account for 25 percent of the criteria for who ultimately moves to the next round, with a panel of three judges providing the remainder of the decision-making power.

Also representing UC Davis in the competition is Team Foodisclosure, which proposes low-cost, solar-powered LED lights for raising chickens in regions with less winter sunlight, encouraging the hens to remain productive throughout the year.

To vote, click on the “Like” icon at the top of these pages:

Team UC Davis

Team Foodisclosure

See a video about the Global Village game below:

See the Foodisclosure slideshow here:



Posted on Thursday, May 2, 2013 at 10:27 AM
  • Author: Bradley Hooker
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