A little piece on spiders in the UC Master Gardener column of the Contra Cost Times last month caused quite a stir. In answering a question about brown recluse spiders, the writer said: "Brown recluse spiders are not found in California, except in the far southern eastern desert regions, and it is highly unlikely that you have a population in your backyard. As of now, there has not been one confirmed brown recluse spider bite in the state."
The UC Integrated Pest Management Program reports similar information on its Web site: "There are no populations of the brown recluse Loxosceles reclusa, in the state and fewer than 10 verified specimens have been collected over several decades in California. Yet people frequently relate stories in which they or someone they know was supposedly bitten by a brown recluse in California."
This past weekend, the Contra Costa Times reported that the assertion about brown recluse spiders sparked heated debate. Many residents who responded said they were sure the brown recluse spider is in the Bay Area. To find out for certain, UC Riverside entomologist Richard Vetter offered to identify any spider suspected of being a brown recluse.
Residents are invited to carefully capture spiders they think may be brown recluses and deliver them to the Contra Costa County UC Cooperative Extension office.
At the risk of giving readers the heebie-jeebies, here are some things that distinguish the poisonous brown recluse from harmless garden spiders:
- Six eyes arranged in pairs, with one pair in front and a pair on either side. (Most spiders have eight eyes.)
- A dark violin shape on the cephalothorax (the portion of the body to which the legs attach).
- Uniformly light-colored legs, no stripes, no bands.
- Uniformly colored abdomen which can vary from cream to dark brown depending on what it has eaten.
In the past week, many news media outlets reported on research by UC Davis food chemist Alyson Mitchell that was published in the June 23 issue of the Journal of Agricultural and Food Chemistry. For example, on July 5, the BBC News titled its story "Organic tomatoes 'better' for heart." The story was picked up in Australia, India, Africa and many American publications.
Mitchell and her colleagues studied dried tomatoes that had been collected over 10 years for an unrelated research project that compared organic, conventional and intermediate growing methods. They found statistically higher levels of quercetin and kaempferol aglycones in organic tomatoes, according to the journal article. The substances are flavonoids believed partly responsible for lower rates of cardiovascular disease and some cancers in people who eat lots of fruits and vegetables. Mitchell received a $34,000 ANR Core Issues Grant in 2004 to conduct her research.
According to the Sacramento Bee article, published July 4, the research adds to a conflicting body of knowledge about whether organic foods provide significant nutritional benefits.
"There's a lot of confusion," Mitchell is quoted in the Bee. "For every study that shows there's a difference, there's another that shows there isn't."
Bee writer Carrie Peyton Dahlberg reported that Mitchell said the higher levels of flavoniods in the organically grown tomatoes may be due to an increase in organic matter and overall soil fertility due to organic production methods.
"That meant growers didn't need to use as much compost to keep nitrogen levels high. And without that extra boost of growth-promoting nitrogen, plants seemed to devote more energy to producing flavonoids," Dahlberg wrote.
However, the article notes that Mitchell said that the research findings don't necessarily mean that all organic tomatoes would contain more flavonoids.
I hate to throw a wet blanket on the holiday, but a heat wave and fireworks are colliding with dry grass and shrubs to create what could become a fiery Fourth of July. The Los Angeles Times reported yesterday that firefighters are already battling a barrage of blazes. Fires in Los Padres National Forest, near Pyramid Lake, two in San Diego County and mop up in the Lake Tahoe area are keeping firefighters busy before the holiday even begins.
And the worst may be yet to come. A UC Cooperative Extension specialist at UC Berkeley, Max Moritz, teamed up with researchers at the University of Utah to create a new way to predict when vegetation dries to the point it is most vulnerable to large-scale fires in the Santa Monica Mountains near Los Angeles, according to a University of Utah news release.
This year's forecast says the highest-risk fire period will begin July 13 – weeks earlier than usual. The San Francisco Chronicle points out the date is Friday the 13th. The study found the amount of March-April-May precipitation can be used to predict the date at which high fire-risk thresholds are reached.
Several UC Cooperative Extension scientists are excellent sources of information on fires -- primarily on such topics as urban-wildland interface fires, biomass harvesting to reduce forest fuels and fire hazard, and wildland fire science and management. Contact information is available on UCCE's experts list.
UC Berkeley's Moritz has also conducted research that confounds conventional wisdom about managing wilderness for wildfire prevention. In a UC Berkeley news release writer Sarah Yang reported in 2004 that Moritz and his colleagues found that the age of vegetation in California's shrublands does not strongly influence the probability of wildfires.
"If the goal is to save people's homes and avoid loss of life, then treating extensive portions of the landscape to create a mixture of young and old vegetation is not money well spent," Moritz is quoted.
Moritz said fire management strategies should focus on more effective use of resources, like creating defensible space immediately around people's homes and communities, attempting to fire-proof structures, and developing better evacuation procedures.
"We also have to ask ourselves whether it makes sense to build homes in areas at risk for fire or natural hazards in the first place. Doing so is inherently dangerous, and it is at least in part an urban planning problem," he is quoted in the release.
I will be camping in the tinder-dry Sierra Nevada for a few days following the Fourth, so I will update this blog when I return (providing a forest fire doesn't close Highway 168 while we are enjoying the comfortable temperature at the 7,000-foot elevation.) Rest assured, I will suffocate the campfire after we're done roasting marshmallows.
Happy Independence Day!
The prestigious journal Science features a cover story on the work of UC Davis plant scientists Jorge Dubcovsky and Jan Dvorak in its current issue. The article is not written at the eigth-grade reading level, the typical goal of the general media. For the reader willing to devote some extra concentration, and perhaps look up a few words in the dictionary, there are many interesting facts. For example, the article says 620 million tons of wheat are produced annually worldwide, providing about one-fifth of the calories consumed by humans. About 95 percent of the wheat crop is common wheat, used for making bread, cookies, and pastries, and the other 5 percent is durum wheat, used for making pasta and other semolina products.
The transition from hunting and gathering to agrarian lifestyles in western Asia was a threshold in the evolution of human societies, the authors wrote. Seeds of free-threshing wheat began to appear in archaeological sites about 10,000 years ago.
The article continues with Dubcovsky and Dvorak 's review of recent insights from molecular genetics and genomics "to understand how gene mutations and genome ploidy paved the way for successful domestication of modern cultivated wheat varieties."
From Websters: "ploidy n. the condition of having or lacking one or more chromosomes than the number found in the normal diploid set."
UC Cooperative Extension farm advisor Paul Vossen was among 22 world-class judges at last month's Los Angeles International Extra Virgin Olive Oil Competition, according to an article in the San Francisco Chronicle.
The article said the event, part of the Los Angeles County Fair, has now become one of the premier olive oil competitions in the world.
There were many gold medalists who are repeat winners, among them California Olive Ranch, McEvoy, Round Pond, the Olive Press, Apollo, Pacific Sun and Stella Cadente.
"The state of American olive oil is in a very, very good spot," Vossen was quoted in the article, written by Olivia Wu. "The olive oils we're producing are excellent."