Posts Tagged: almonds
An airborne fungus from Europe, ganoderma adspersum, has been killing almond trees in the San Jaoquin Valley since it was discovered in the area five years ago, reported John Cox in the Bakersfield Californian.
The fungus rots wood from the inside out, usually weakening the trunk a ground level.
Three kinds of ganoderma fungus infections were identified recently in California almond orchards; University of California researchers say 94 percent of the cases were of the adspersum variety.
"We are seeing those trees collapsing at 11, 12, 15 years old,” said UC Cooperative Extension orchard systems advisor Mohammad Yaghmour. The infections have results in the removal of orchards at less than half their typical 20- to 25-year life span.
Spraying for the fungal disease is ineffective. Yaghmour believes that in time researchers will identify a root stock that is resistant to the fungus.
Last May, a Turlock almond grower noticed nearly all the nuts on a row of trees in his orchard had fallen to the ground.
“It looked like we shook this row,” he said. “I was scared. I thought the whole orchard was going to go.”
He called UC Cooperative Extension.
UCCE Integrated Pest Management advisor Jhalendra Rijal, who serves Stanislaus, San Joaquin and Merced counties, determined the cause was an infestation of brown marmorated stink bug (BMSB), an invasive pest from Asia. For years, BMSB had only been found in urban areas of California – most notably a 2013 infestation in midtown Sacramento.
With few natural predators and a wide host range – including apples, pears, cherries, corn, tomatoes, grapes and a variety of landscape trees – the population eventually moved into agricultural areas, first appearing in crops in 2016 in Stanislaus County. Rijal has been doing BMSB research since then.
Rijal hosted a gathering of farmers and pest control advisers Aug. 13, 2019, in the Turlock almond orchard to give them a first-hand view of the pest and the problems it causes.
BMSB are hard to find in orchards. They lay greenish colored eggs on the underside of leaves, typically in a cluster of 28 eggs. The majority of damage is caused by adults, which sting the hull with a needle-like mouth part to get to the nut. The sting can even penetrate the almond's hard shell when the fruit is mature.
Globs of clear sticky sap appear on the damaged almond hulls, typically indicating nut loss inside. Early season (March-April) infestation leads to the most severe yield loss when the nuts drop to the ground. The best way to confirm the damage is caused by BMSB is to use a trap.
“I recommend growers and pest control advisors put BMSB traps in orchard edges if they suspect BMSB damage or if the orchard is located near potential overwintering structures or host crops,” Rijal said. “BMSB are good flyers and active throughout the season, damaging nuts from April through the fall. But the most substantial damage happens in the spring through early summer."
If the orchard is close to BMSB-favored host plants, more damage is seen. A particularly troublesome neighbor plant is tree-of-heaven.
“Tree-of-heaven is a magnet for BMSB,” Rijal said, pointing to an abandoned farmhouse site on an adjacent property. “Tree-of-heaven has a nice fruiting structure that can support a lot of BMSB.”
Also an Asia native, tree-of-heaven was brought to California by Chinese immigrants during the Gold Rush. The roots, leaves and bark are used in traditional Chinese medicine. But its rapid growth and ability to clone itself to develop thick groves make it a noxious weed.
BMSB isn't a serious pest in its homeland because it is controlled by a natural enemy. Charles Pickett, the California Department of Food and Agriculture biological control scientist, shared a mounted sample of a Samurai wasp from Asia, Trissolcas japonicus, which lays its eggs in BMSB eggs.
“The parasite attacks most of the eggs in the field in eastern Asia,” Pickett said. “It's our goal to release the wasp in California. We first need a special permit to make sure it won't harm our environment and doesn't attack any beneficial stink bugs.”
The Samurai wasp has already found its own way to some BMSB infestation sites in the Eastern U.S. and in Los Angeles.
“We hope to someday release the parasitic wasp,” Pickett said. “It won't eradicate BMSB, but it will help.”
One of the forces driving agricultural experiments in California's fertile San Joaquin Valley is climate change, reported Mark Schapiro on Grist.org. Although some sources still don't feel completely comfortable with the concept.
"Whether it's carbon built up in the atmosphere or just friggin' bad luck, the conditions are straining us," said John Duarte, president of Duarte Nursery.
The state's fruit and nut orchards are taking the most heat as conditions change. A fruit or nut tree planted today may be ill-suited to climatic conditions by the time it begins bearing fruit in 5 or 10 years. Between 1950 and 2009, “chill” hours trees needed annually to reboot trees' metabolic system for the spring bloom had already declined by as much as 30 percent, according to a California Department of Food and Agriculture study.
“If trees haven't had that low-chill period when they wake up in the spring, it's like being up all night and then trying to go to work.” said Mae Culumber, a nut crop advisor with UC Cooperative Extension in Fresno County.
Researchers have already observed that cherry, apricot, pear, apple, pecan and almond trees are often less productive than they used to be.
The article said farmers may turn to pistachio trees to weather a warmer and dryer California. Pistachio trees require one-third to one-half as much water as almond trees. During droughts, pistachio tree metabolism slows and when water returns, they start producing nuts again. And they can produce nuts for 80 years or longer, almost four times the life span of an average almond tree.
For field crops, scientists are looking at improving the soil and transforming growing systems to help farmers adapt to the warming climate.
“When I drive to the Central Valley, I get goosebumps; I feel the urgency,” UC Davis agronomist Amélie Gaudin said. “I see an agriculture that is basically hydroponics. It's like a person being fed/kept alive by an IV.”
“What happens when you no longer have the sugar-water?” she adds.
Gaudin is focusing on using agroecological principles to develop efficient and resilient cropping systems. Planting cover crops and reducing tillage show promise for mitigating the impact of climate change in the valley.
No, it's not Valentine's Day, yet. Yes, the almonds are blooming. No, it's not spring. But it looks like spring in Benicia. The almonds are...
Benicia resident Gordon Hough captured this image of a bee nectaring on a Pyrus calleryana (Bradford pear or another cultivar) at the Benicia State Recreation Area on Monday, Jan. 21, as identified by Daniel Potter, UC Davis professor of plant sciences.
Almonds are blooming in Benicia. (Photo by Kathy Keatley Garvey)
Because periodic droughts will always be a part of life in California, the UC California Institute for Water Resources (CIWR) produced a series of videos to maintain drought awareness and planning, even in years when water is more abundant.
The final video of the three-part series, which focuses on drought strategies for citrus, was launched April 6 on the UCTV Sustainable California channel. The first episode, which centered on alfalfa production, premiered Feb. 2 on the UCTV Sustainable California channel. The second video, on almonds, was launched March 2 on Sustainable California. A trailer with clips from all three episodes is here.
The videos are inspired by a collection of 19 drought tips produced by CIWR in collaboration with UC Agriculture and Natural Resources researchers during the drought of 2010-16. The tips cover a broad spectrum of California crops, from alfalfa to walnuts. Topics also include salt management, use of graywater in urban landscapes, and the use of shallow groundwater for crop production.
The drought tips collection and the drought tip videos were sponsored by the California Department of Water Resources. Following are links to each of the videos:
The CIWR drought tip series opens with Cannon Michael of Bowles Farming in Los Banos. The alfalfa grower works with UCCE specialist Dan Putnam. “There's a lot of misunderstanding about alfalfa as a crop,” Michael said. “It does take water to grow it, as with anything, but you get multiple harvests of it every year.”
The second episode features almond producer Raj of Meena farms. He works with David Doll, UCCE advisor in Merced County. “One positive of this drought,” Meena said, “is that it has forced us all to be more efficient in how we use our water.”
The series finale features Lisa Brenneis of Churchill-Brenneis Orchard in the Ojai Valley of Ventura County. She worked with UCCE advisor Ben Faber to install a new water-efficient irrigation system. “Irrigation is the only job we really have to do,” Brenneis said, “and we have to get it as right as we can.”
For a complete list of drought tips, see http://ucanr.edu/drought-tips.