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

UC Blogs

Recent cases of hantavirus a reminder to be mindful of deer mice

Deer mice are the most abundant and widely distributed mammals in North America.
Two people in California were recently diagnosed with hantavirus infection, and one has died. Both of them spent time at Curry Village in Yosemite National Park, according to the California Department of Public Health. These new cases of hantavirus are a reminder to be aware of the threat and to take precautions to prevent infection.

Hantavirus is a very rare but very serious disease. About one-third of cases identified in California are fatal, CDPH reports. Since hantavirus was first identified in 1993, there have been 60 cases in California and 587 cases nationally. The two recent cases bring the total California case count for 2012 to four.

Hantaviruses are a group of viruses spread mainly by deer mice. The UC Integrated Pest Management Program recently published a comprehensive online Pest Note about deer mice, which details identification, biology and behavior, damage and management. The publication says deer mice are the most abundant and widely distributed mammal in North America. Proficient jumpers and runners, deer mice were so named for their agility.

Because deer mice prefer forests, grasslands and agricultural crops, they aren’t normally found in urban and residential areas unless fields, forests or other suitable habitats are close by. Deer mice shed the hantavirus in their saliva, urine and droppings. A person may be exposed to hantavirus by breathing contaminated dust after disturbing or cleaning rodent droppings or nests or by living or working in rodent-infested settings. There is no evidence that North American hantavi­ruses can spread from one person to another.

The most effective way to avoid contract­ing hantavirus from deer mice is to keep them out of houses, cabins, and dwell­ings by rodent-proofing and excluding them from these structures by sealing all small gaps and cracks. Once deer mice infest a dwelling, it is critical to avoid working and sleeping in these areas until the infestation has been controlled and the area has been made safe for humans.

Before occupying an infested building, open the doors and windows to air out the room for at least 30 minutes. Where possible, use an electric fan on window­sills and in door entrances to assist the process. Be sure to vacate the building during the ventilation process to prevent inhaling aerosolized particles. Wearing a commercially available cloth or paper breathing mask offers some protection and is better than no protection at all. However, only an approved respirator equipped with high-efficiency particu­late air (HEPA) filters offers total respira­tory protection against airborne viruses.

It is important to wear nonfabric gloves (e.g., rubber, latex, vinyl, or nitrile) when cleaning deer mouse-infested buildings. Because humans can con­tract the virus by inhaling aerosolized deer mouse urine and feces, never stir up dust by vacuuming or sweeping or through any other activity.

To disinfect potentially contaminated areas, thor­oughly wet trapped deer mice, droppings, and nests with an appropriate disinfectant solu­tion such as Lysol or a 10% hypochlorite (bleach) solution. To make this bleach solution, mix 1 1/2 cups of household bleach in 1 gallon of water (or one part bleach to nine parts water). Note that a bleach solution may damage rugs and fabrics and irritate skin. Wear nonfabric gloves whenever touching or cleaning contaminated surfaces or when handling mouse nests, dead mice, or mouse traps.

Once everything has soaked for 10 min­utes, remove all nest material, mice and droppings with a damp towel and then mop or sponge the area with the disin­fectant solution. Upholstered furniture and carpets can be shampooed and steam cleaned. If you wish to reuse the gloves used while cleaning contaminated areas, you must properly disinfect them before removal. After removing the gloves, it is important to thoroughly wash hands with soap and water or use a waterless alcohol-based hand sanitizer when soap is un­available and hands aren’t visibly soiled.

The UC IPM Pest Note on deer mice was written by Niamh Quinn, Evolution, Ecology, and Behavior, University of Liverpool, Liverpool, U.K.,; Roger Baldwin, UC Cooperative Extension advisor, Statewide IPM Program, Kearney Agricultural Research and Extension Center, Parlier; and Bob Timm, director, UC Hopland Research and Extension Center,. For additional up-to-date information on rodent cleanup, visit the Centers for Dis­ease Control and Prevention Web site,

Posted on Friday, August 17, 2012 at 12:43 PM

Have you seen a Polyphagous shot hole borer lately?

The Polyphagous shot hole borer.
The “Invasive Ambrosia Beetle Public Meeting” that took place on Aug. 14 in Riverside, Calif., turned the spotlight on a beetle named “Polyphagous shot hole borer.”  The PSHB has spread in Los Angeles and Orange counties. Both the beetle and a fungus it spreads were found on several backyard avocado trees in residential neighborhoods in these counties earlier this year. The beetle is responsible for the death of box elder trees in Long Beach in 2010. The box elder is one of the best hosts for the PSHB.

The beetle is very small and hard to see. Females are black in color and 0.07-0.1 inch long.  The beetle burrows into the wood, leaving a hole (there are often many entry holes on an infested tree). The beetle then infects the host plant with a new Fusarium fungus, which it carries in its mandibles, a result of a symbiotic relationship between the beetle and fungus.

The fungus, in turn, attacks the vascular tissue of the tree, disrupting water and nutrient flow within the tree and eventually causing branch dieback. Fusarium dieback symptoms on avocado include a white powdery exudate — either dry or surrounded by wet discoloration of the outer bark — around a beetle entry hole.

The panelists at the public meeting were UC Riverside's Mary Lu Arpaia, UC Cooperative Extension specialist in the Department of Botany and Plant Sciences at UC Riverside, subtropical horticulture; Akif Eskalen, UCCE specialist in the Department of Plant Pathology; Mark Hoddle, UCCE specialist in the Department of Entomology and the director of the Center for Invasive Species Research; Timothy Paine, professor in the Department of Entomology; and Richard Stouthamer, professor in the Department of Entomology. They were joined by Zvi Mendel of the Agricultural Research Organization, Israel; Donald Hodel, UCCE advisor in Los Angeles County; Tom Roberts of the pest management industry; and Tom Coleman of the U.S. Department of Agriculture Forest Service.

The panelists explained that the beetle may have come from Southeast Asia or possibly Africa. There is no good solution for dealing with the beetle and the fungus. Preventive management, including sanitation, is the best option.

Several speakers advised not to move infested wood away from an infected zone and not to accept mulch from infected areas. Growers were advised to monitor the nutritional status of their trees, chip infested branches within the infested area and sterilize tools between cuts. Proper irrigation of trees was also recommended because over-watered and under-watered trees attract this beetle.

The PSHB appears to be “tasting” different trees in search for a good host. Neither the adults nor the larvae eat the plants and wood; they live in “galleries” within the tree and feed on the fungus.

Much about the PSHB remains unknown. What is known is that the beetle population can expand its range by about 12 miles a year. The beetle flies from tree to tree, and up and down a tree as well.  Facilitated movement — packing wood, firewood — helps transport the beetle to far off places.

Chemical control has, so far, not been effective on the PSHB. Tarping or enclosing infested material is one of the solutions being considered.  Heat treatment, fumigation and burning are other options on the table. Chipping and grinding are the best options at the moment.

The beetle is able to reproduce in only a small number of tree species. Known suitable hosts of the both PSHB and fungus are box elder, avocado, castor bean, English oak, coast live oak, silk tree, liquidambar, Coral, Titoki, California sycamore, Blue Palo Verde and big leaf maple.   

The finger points to a beetle entry hole on an avocado trunk. Photo credit: Eskalen Lab, UC Riverside.
If you find entry holes on an avocado tree that are surrounded by white powdery exudates, scrape off the bark layer around the infected area to see the canker (discolored wood).  Then follow the gallery to look for the beetle. It is important that you not move infested avocado wood out of the infested area. Look for other hosts — castor bean, box elder, coast live oak — showing symptoms of the beetle/disease. 

If you suspect you have found the PSHB or seen symptoms of Fusarium dieback in your grove or surrounding areas in other host plants, please contact your local farm advisor, pest control advisor, county ag commissioner office or UC Riverside's Dr. Akif Eskalen at 951-827-3499 or  You can also call the California Avocado Commission at 949-341-1955.

The public meeting in Riverside was part of a longer three-day meeting that was organized by the Hofshi Foundation with additional sponsoring from the UCR Center for Invasive Species Research, the Entomology, Plant Pathology and Microbiology, and Botany and Plant Sciences departments, UC Cooperative Extension, the Los Angeles Arboretum, the Huntington Botanical Gardens and the California Avocado Commission.

An example of wood discoloration due to Fusarium dieback. Photo credit: Eskalen Lab, UC Riverside
An example of wood discoloration due to Fusarium dieback. Photo credit: Eskalen Lab, UC Riverside

Multiple entry holes on avocado trunk. Photo credit: Eskalen Lab, UC Riverside.
Multiple entry holes on avocado trunk. Photo credit: Eskalen Lab, UC Riverside.

Posted on Friday, August 17, 2012 at 10:37 AM

Comb honey: no compromising

It's like going back to nature, but it's always been there.

Honey bee expert Norman Gary, emeritus professor in the Department of Entomology at UC Davis, says that honey is at its best "when it is sealed in the comb."

"It's packaged in the original, natural container that preserves its flavor and goodness until consumed," he said. "Some of these qualities are compromised during the harvesting process."

In his book, Honey Bee Hobbyist, the Care and Keeping of Bees, Gary writes that, "When honey is extracted, it flies through the air in tiny droplets and spreads thinly on the interior walls of the extractor tank. This exposure to air causes some flavor loss. You can enjoy the full flavor of honey be eating bite-size pieces of freshly constructed honeycomb. You can also chew beeswax like chewing gum. Swallowing beeswax is an option, but it doesn't benefit you in any way because it is indigestible."

Gary, who has been keeping bees for more than six decades, offers these tips to beekeepers in his book: "Here is a simple way to produce a small amount of comb honey. Remove a comb frame from a honey super. Replace it with a frame with the comb removed except for a 1-inch strip at the top to encourage bees to build new comb in the frame. At the beginning of an expected honey flow, place the frame in the center of the honey super immediately above the queen excluder. Bees will fill in the frame with new comb."

The honey bee, first brought to what is now the United States (Jamestown, Virginia) in 1622 and then transported to California in 1853, has long been revered for its pollination services and the products it produces. Early Americans prided themselves on finding feral honey bee colonies in bee trees and raiding the honey.

The practice continues today.

Truly, comb honey is one of nature's treasures. Many beekeepers and honey enthusiasts just cut the comb into small squares and eat it immediately. What to do if it's not consumed right away?

Gary says to seal the comb honey into zip-locked plastic bags and freeze it. It will, he says, "keep indefinitely" in the freezer.

Honey bee on comb. (Photo by Kathy Keatley Garvey)
Honey bee on comb. (Photo by Kathy Keatley Garvey)

Honey bee on comb. (Photo by Kathy Keatley Garvey)

Posted on Wednesday, August 15, 2012 at 11:07 AM
Tags: beekeepers (2), comb honey (1), Norm Gary (1)

Beetle threat to California's oak and avocado trees

Polyphagous shot hole borer (Photo: Gevork Arakelian)
The Polyphagous shot hole borer is a beetle that attacks oak and avocado trees, causing branch dieback and eventually death. The beetle bores into the trees and spreads a fungus that, in turn, attacks the vascular tissue of the tree and disrupts water and nutrient flow. The beetle also attacks coast live oak, box elders and other trees.

Both the fungus and the beetle were discovered on several backyard avocado trees in residential neighborhoods and a commercial avocado grove in Los Angeles County earlier this year.

Scientists from the University of California, Riverside, and others are meeting on Aug. 12-14 in Riverside to discuss the beetle, its biology, the fungus it spreads, and strategies to effectively monitor and control the pest.

The public is invited to attend the free open session of the three-day meeting from 2 p.m. to 5 p.m. on Tuesday, Aug. 14, at the Marriott Riverside Hotel, 3400 Market St., Riverside, Calif. 

At the public meeting, the scientists will address the new beetle/fungus complex and explain what problem it poses, the extent of the problem in California, what detection and control measures are currently available, and how Israel is dealing with the same pest. A Q&A session is scheduled for 4:25 p.m.

For more information, including how to register for the public meeting, visit:

Posted on Wednesday, August 8, 2012 at 8:17 AM

UC research predicts climate change effects in California

Walnuts depend on synchronization between male and female flowering that is regulated by the amount of chilling hours. Climate change may reduce winter chill and disrupt pollination.
A report on climate change and its effects on California released on July 31 by the California Natural Resources Agency and the California Energy Commission features more than 30 reports by UC scientists. Experts from UC Berkeley, UC Davis, UC Merced, UC Riverside, UC San Diego/Scripps Institution for Oceanography, UC Santa Cruz, UC Cooperative Extension and Lawrence Berkeley National Laboratory contributed to "Our Changing Climate."

The report, the third such assessment since 2006, provides new data to help Californians plan and adapt to climate change.

"Significant increases in wildfires, floods, severe storms, drought and heat waves are clear evidence that climate change is happening now. California is stepping up to lead the way in preparing for — and adapting to — this change," said state Secretary for Natural Resources John Laird. "These reports use cutting-edge science to provide an analytical roadmap, pointing the way for taking concrete steps to protect our natural resources and all Californians."

A study led by Louise Jackson, UC Cooperative Extension specialist in the Department of Plant Sciences at UC Davis, took an inventory of greenhouse gas emissions on Yolo County farmland and studied how agriculture can adapt to climate change.

An op-ed co-authored by Richard Rominger, a farmer and member of the UC President’s Advisory Commission on Agriculture and Natural Resources, and published in the Sacramento Bee noted the study “found that urban land accounts for 70 times more greenhouse gas emissions per acre than cropland.” A good reason to protect cropland.

The website based on the Jackson study provides a tool for Yolo County farmers and policymakers to plan for the changes that occur at the regional level with climate change.

For planning on a larger scale, a coalition of scientists and state agencies has developed Cal-adapt, a web-based climate adaptation planning tool. Cal-adapt allows users to identify potential climate change risks in specific geographic areas throughout the state. Users can query by location or click on an interactive map to explore what climate impacts are projected to occur in different regions of the state.

“Climate change is expected to affect the quantity and timing of water flow in the state,” explained Kaveh Madani, a former postdoctoral research scholar in UC Riverside’s Water Science and Policy Center, who led a research project on climate change effects on hydropower production, demand, and pricing in California. 

“If California loses snowpack under climate warming, these high-elevation reservoirs might not be able to store enough water for hydropower generation in summer months when the demand is much higher and hydropower is priced higher,” said Madani, currently an assistant professor of civil, environmental, and construction engineering at the University of Central Florida. “California might, therefore, lose hydropower in warmer months and hydropower operators may lose considerable revenues.”

Max Moritz, UC Cooperative Extension specialist in the Department of Environmental Science, Policy and Management at UC Berkeley, contributed a paper to the extensive report about increased vulnerability to wildland fires in the state.

“The incredible breadth of studies, as well as the depth of their analyses, reveals just how much the University of California has to offer in preparing us all to adapt to a changing climate,” Moritz said of the full report.

Read more on specific campus researchers' contributions to the report in these news releases:

For highlights of the reports in Our Changing Climate, see the California Energy Commission’s press release. The full reports can be downloaded from the CEC’s website.


Posted on Friday, August 3, 2012 at 10:56 AM

First storyPrevious 5 stories  |  Next 5 stories | Last story

Webmaster Email: