Posts Tagged: Avocado

During California Invasive Species Action Week, learn about invasive species

Californians can help in the fight against invasive species by learning and participating during California Invasive Species Action Week, June 2–10.

During the week, the UC Statewide Integrated Pest Management Program invites the public to spend lunch learning about invasive tree killing pests, aquatic nasties like quagga mussels and nutria, and how the invasive weed/wildfire cycle is altering our ecosystems. http://ucanr.edu/sites/invasivelunch/

The invasive species killing trees is causing sugar volcanoes to erupt on avocado trunks and branches that might be infected with Fusarium dieback. Fusarium dieback is a invasive, beetle-vectored disease that causes damage on avocado and more than 39 other tree species. The disease has spread in urban forests and wild lands in the Los Angeles basin since early 2012, and in Orange and San Diego counties since early 2013 and Ventura County in 2015.

The symptoms — staining, sugary exudate, gumming and beetle frass — are often noticed before the tiny beetles (1.5–2.5 mm) are found.

As its name suggests, these beetles bore into trees. Near or beneath the symptoms, you might notice the beetle's entry and exit holes into the tree. The female tunnels into trees forming galleries, where she lays her eggs. Once grown, the sibling beetles mate with each other so that females leaving the tree to start their own galleries are already pregnant. Males do not fly and stay in the host tree.

Shothole borers have a special structure in their mouth where they carry two or three kinds of their own novel symbiotic fungi. Shothole borers grow these fungi in their tree galleries. It's these fungi that cause Fusarium dieback disease, which interrupts the transportation of water and nutrients in the host tree. Advanced fungal infections will eventually lead to branch dieback.

Early detection of infestations and removal of the infested branches will help reduce beetle numbers and therefore, also reduce the spread of the fungus.

• Chip infested wood onsite to one inch in size or smaller. If the branch is too large to chip, solarize them under a clear tarp for several months
• Avoid movement of infested firewood and chipping material out of infested area

Avocado is one tree host. Shothole borers successfully lay eggs and grow fungi in many tree hosts, with some of these trees susceptible to the Fusarium dieback disease. For more information about tree host species, where the shothole borer is in California, and what symptoms look like in other tree hosts, visit the UC Riverside Eskalen Lab website or the Invasive Shot Hole Borers website.

Content in this post taken from the UC IPM Avocado Pest Management Guidelines. Faber BA, Willen CA, Eskalen A, Morse JG, Hanson B, Hoddle MS. Revised continuously. UC IPM Pest Management Guidelines Avocado. UC ANR Publication 3436. Oakland, CA.

Avocados go from Meso-American backyards to 'world domination'

Avocados, now riding a tide of popularity appearing on toast in cookbooks and trendy restaurant menus, came late to commercial agriculture, reported Cynthia Graber and Nicola Twilley in Gastropod, a podcast that looks at food through the lens of science and history.

The 48-minute story features Mary Lu Arpaia, UC Cooperative Extension specialist based at the UC Kearney Agricultural Research and Extension Center in Parlier. Arpaia runs the UC avocado breeding program and is now studying varieties that will do well in the San Joaquin Valley climate.

On Gastropod, Arpaia outlined avocados' humble beginnings in their native Mexico and Central America.

"It was grown as a dooryard crop tree and valued for thousands of years," Arpaia said. "There was no intensive production of avocado until the industries in California and Florida started about 100 years ago."

The most popular variety is the Hass, which is derived from a seed planted in La Habra Heights by a hobby horticulturist, Rudolph Hass, a U.S. Postal Service worker.

"The thing against it (the Hass variety) was it turned black when ripe. It's a great tree with great fruit, but it's black," Arpaia said. "So it just shows how things have changed."

Consumers now embrace Hass' black, bumpy coat.

Graber and Twilley spent time on the show describing the "avocado toast" sensation around the globe. The duo quoted an article in Vogue that says 3 million new pictures of avocado toast are uploaded to Instagram every day.

The future for avocados looks bright. Already China imports 32,000 tons of avocados annually, but the market potential is much greater.

"I can't even imagine how big avocado will get in China," said one of the Gastropod hosts.

San Joaquin Valley farmers may one day produce avocados

Despite hot summers and cold winters, UC Cooperative Extension specialist Mary Lu Arpaia believes the San Joaquin Valley could be home to expanded California avocado production, reported Gregory Barber on Wired.com. 

Currently, most of the state's avocados are grown in the mild coastal areas of San Diego and Ventura counties, where consumer-favorite Hass avocados flourish. But high land value and low water quality are limitations on the industry. The vast and fertile San Joaquin Valley beckons, but summer temperatures that frequently top 100 degrees and occasional winter freezes aren't ideal for Hass.

Arpaia has planted a variety of avocado cultivars at the UC Lindcove Research and Extension Center in eastern Tulare County to determine which trees produce creamy, nutty avocados, and maintain other desirable traits - such as high yield and small tree size - while subjected to the valley's climate extremes.

The California Avocado Commission funded the orchard's establishment.

"The industry wasn't really too keen about me putting a site here (at Lindcove)," Arpaia said. "But I'm stubborn and that's why it's here."

Each year three new avocado varieties are planted in the orchard. Though the breeding process is slow, Arpaia dreams that one day avocados will be sold in supermarkets much like the wide variety of apples.

"We're probably 20 years behind the apple industry at this point," Arpaia said. "Do we have anything out here that's going to achieve that dream?"

Finding an avocado variety ideal for valley temperatures has other benefits. It would give citrus farmers another option should their industry be threatened by Huanglongbing (HLB) disease. Already, the pest that spreads HLB, Asian citrus psyllid, is established in some parts of the valley and spreading. Once a tree is infected with HLB, it cannot be cured.

“Growers have made good money on avocados,” Arpaia said. “In the San Joaquin Valley, water is relatively cheap and we have better water quality than San Diego County. There are good, well-drained soils. Avocados' frost sensitivity is similar to lemons. If farmers have property where they can grow lemons, they could try avocados.”

 

Drought is forcing changes in California ag

California farmers are changing the way they grow avocados to deal with three distinct problems that are cutting into profits: rising fertilizer costs, spikes in water rates, and competition from avocados grown in Peru, Chile and Mexico, says University of California Cooperative Extension farm adviser Gary Bender. He was quoted in a story on Takepart.com about looming price increases for much-loved guacamole.

It takes 74 gallons of water to produce one pound of avocados — and drought-stricken California produces 95 percent of the avocados grown in the United States, wrote reporter Padma Nagappan.

Bender has been working with several farmers to experiment with high-density avocado planting, in which the trees are pruned to grow up rather than out. Growing more trees on less land will reduce water costs.

“The only way you can compete with cheaper imports and the high cost of water is if you go high-density and get more production per acre," said a San Diego area farmer.

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An article in Growing Produce said the state has issued curtailments to some farmers who hold surface water rights. Because water rights law is so complex and because this is the first time many growers have had to navigate the finer details of water rights, Brenna Aegerter, University of California Cooperative Extension advisor in San Joaquin County, suggests that growers consult a professional for targeted advice.

Because of reduction in surface water availability, many growers are turning to groundwater to irrigate their crops. However, groundwater presents its own set of challenges, Aegerter says.

“There's a shallow water table but it's not good quality,” Aegerter says. “It's salty water. I think right now the main concern is what the water quality is going to be — whether it's going to be salty, and whether that will affect the crops.”

In the Westlands Water District, growers are using a combination of increased reliance on groundwater and fallowing for their water management plans, according to Tom Turini, UCCE advisor in Fresno County.

“The groundwater is lower quality than the district water — with levels of total dissolved salts and toxic ions varying from well to well — but generally higher than ideal, ” Turini says.

Southern California farmers harvesting uncommonly small avocados

An unusual weather pattern over the last year has led to an abundance of small-sized avocados on Southern California trees, reported National Public Radio. The radio news service sought an explanation from Gary Bender, UC Cooperative Extension advisor in San Diego County.

Bender said in his 29 years on the job he has not seen such tiny avocados as those being picked this year.

Typically, several months after pollination, high temperatures in July cause a significant amount of developing fruit to drop to the orchard floor. That didn't happen in the summer of 2012. The heavy crop on the tree, combined with low rainfall, cool temperatures and sluggish photosynthesizing, has likely caused the stunting, Bender said.

NPR reporter Alastair Bland found avocados being sold 6 or 10 to a bag for $1.

"That's just ridiculous," Bender said.

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