The fungus is a new species of Fusarium. Scientists are working on characterizing its specific identification. It is transmitted by the Tea Shot Hole Borer (Euwallacea fornicatus), an exotic ambrosia beetle that is smaller than a sesame seed. The disease it spreads is referred to as “Fusarium dieback.”

“This beetle has also been found in Israel and since 2009, the beetle-fungus combination has caused severe damage to avocado trees there,” said Akif Eskalen, an extension plant pathologist UC Riverside, whose lab identified the fungus.

To date, the Tea Shot Hole Borer has been reported on 18 different plant species worldwide, including avocado, tea, citrus, guava, lychee, mango, persimmon, pomegranate, macadamia and silk oak.

Eskalen explained that the beetle and fungus have a symbiotic relationship.

“When the beetle burrows into the tree, it inoculates the host plant with the fungus it carries in its mouth parts,” he said. “The fungus then attacks the vascular tissue of the tree, disturbing water and nutrient flow, and eventually causing branch dieback. The beetle larvae live in galleries within the tree and feed on the fungus.”

Although the beetle was first detected in Los Angeles County in 2003, reports of its negative impact on tree health were paid no attention until February 2012, when Eskalen found both the beetle and fungus on a backyard avocado tree showing dieback symptoms in South Gate, Los Angeles County. The Agricultural Commissioner of Los Angeles County and the California Food and Drug Administration have confirmed the identity of the beetle.

“This is the very same fungus that caused avocado dieback in Israel,” Eskalen said. “The California Avocado Commission is concerned about the economic damage this fungus can do to the industry here in California.

“For now, we are asking gardeners to keep an eye on their trees and report to us any sign of the fungus or beetle,” he added. “Symptoms in avocado include the appearance of white powdery exudate in association with a single beetle exit hole on the bark of the trunk and main branches of the tree. This exudate could be dry or it can appear as a wet discoloration.”

A team of UCR scientists has been formed to study Fusarium dieback in Southern California. Eskalen and Alex Gonzalez, a field specialist, are already conducting a survey to determine the extent of the beetle infestation and the likely extent of the fungus infection in avocado trees and other host plants. Richard Stouthamer, a professor of entomology, and Paul Rugman-Jones, an associate specialist in entomology, are studying the biology and genetics of the beetle.

Members of the public can report sightings of the Tea Shot Hole Borer and signs of Fusarium dieback by calling (951) 827-3499 or emailing ude.rcunull@nelaksea.

A scientist at Texas A&M’s Texas AgriLife Research and Extension Center is moving a pair of bacteria-fighting proteins naturally occurring in spinach into citrus trees to fight a scourge commonly known as citrus greening. The disease hasn’t faced this defense before and intensive greenhouse testing so far indicates the genetically enhanced trees are immune to its advances.

To read the rest of this article, visit Business Week’s website.

HLB is a bacterial disease that attacks the vascular system of plants. It does not pose a threat to humans or animals. The Asian citrus psyllid can spread the bacteria as the pest feeds on citrus trees and other plants. Once a tree is infected, there is no cure; it typically declines and dies within a few years.

“Citrus is not just a part of California’s agricultural economy; it’s a cherished part of our landscape and our shared history,” said CDFA Secretary Karen Ross. “CDFA is moving swiftly to protect the state’s citrus growers as well as our residential trees and the many prized citrus plantings in our parks and other public lands. We have been planning and preparing for this scenario with our growers and our colleagues at the federal and local levels since before the Asian citrus psyllid was first detected here in 2008.”

Officials are making arrangements to remove and dispose of the infected tree and conduct treatment of citrus trees within 800 meters of the find site. By taking these steps, a critical reservoir of disease and its vectors will be removed, which is essential. More information about the program will be provided at an informational open house scheduled for Thursday, April 5, at the Industry Hills Expo Center, The Avalon Room, 16200 Temple Avenue, City of Industry, from 5:30 to 7:00 pm.

Treatment for HLB will be conducted with the oversight of the California Environmental Protection Agency (Cal-EPA) and will be conducted safely, with advance and follow-up notices provided to residents in the treatment area.

An intensive survey of local citrus trees and psyllids is underway to determine the source and extent of the HLB infestation. Planning has begun for a quarantine of the infested area to limit the spread of the disease by restricting the movement of citrus trees, citrus plant parts, green waste, and all citrus fruit except what is commercially cleaned and packed. As part of the quarantine, citrus and closely related plants at nurseries in the area will be placed on hold.

Residents of quarantine areas are urged not to remove or share citrus fruit, trees, clippings/grafts or related plant material. Citrus fruit may be harvested and consumed on-site.

CDFA, in partnership with the USDA, local agricultural commissioners and the citrus industry, continues to pursue a strategy of controlling the spread of Asian citrus psyllids while researchers work to find a cure for the disease.

HLB is known to be present in Mexico and in parts of the southern U.S. Florida first detected the pest in 1998 and the disease in 2005, and the two have now been detected in all 30 citrus-producing counties in that state. The University of Florida estimates the disease has tallied more than 6,600 lost jobs, $1.3 billion in lost revenue to growers and $3.6 billion in lost economic activity. The pest and the disease are also present in Texas, Louisiana, Georgia and South Carolina. The states of Arizona, Mississippi and Alabama have detected the pest but not the disease.

The Asian citrus psyllid was first detected in California in 2008, and quarantines are now in place in Ventura, San Diego, Imperial, Orange, Los Angeles, Santa Barbara, San Bernardino and Riverside counties. If Californians believe they have seen evidence of HLB in local citrus trees, they are asked to please call CDFA’s toll-free pest hotline at 1-800-491-1899. For more information on the Asian citrus psyllid and HLB visit: http://www.cdfa.ca.gov/phpps/acp/

The pest is called the Asian citrus psyllid, and it is confirmed to be in Imperial, San Diego, Orange, Ventura, Riverside, San Bernardino and Los Angeles counties, which has sparked quarantines in those areas, according to a press release distributed by the Dept. of Food and Agriculture.

For the full article from the Highland Park-Mount Washington Patch, click here.

For more information about the app, what it does and how to get it, visit UC Berkeley’s website or OakMapper.org.

The Southeast Asia native insect has spread throughout parts of the world, including Africa, the Middle East, Europe and Oceania. The closest confirmed detections to the United States was in the Dutch Antilles and in Aruba in 2009.

A landscape contractor in the Laguna Beach area first reported the red palm weevil to authorities, prompting local, state and federal officials to confirm its existence, conduct a door-to-door survey and set 250 traps to determine if an actual “infestation” exists. Others are encouraged to report suspect infestations by calling the CDFA Pest Hotline at 1-800-491-1899.

Although most all palm trees are non-native to California, the palm tree industry generates approximately $70 million in sales annually and date palm growers, most notably found in the Coachella Valley, harvest $30 million worth each year.

Here’s how devastating the pest can be, detailed by the CDFA:

Female red palm weevils bore into a palm tree to form a hole into which they lay eggs. Each female may lay an average of 250 eggs, which take about three days to hatch. Larvae emerge and tunnel toward the interior of the tree, inhibiting the tree’s ability to transport water and nutrients upward to the crown. After about two months of feeding, larvae pupate inside the tree for an average of three weeks before the reddish-brown adults emerge. Adults live for two to three months, during which time they feed on palms, mate multiple times and lay eggs.

Adult weevils are considered strong fliers, venturing more than a half-mile in search of host trees. With repeated flights over three to five days, weevils are reportedly capable of traveling nearly four-and-a-half miles from their hatch site. They are attracted to dying or damaged palms, but can also attack undamaged host trees. Symptoms of the weevil and the larval entry holes are often difficult to detect because the entry sites can be covered with offshoots and tree fibers. Careful inspection of infested palms may show holes in the crown or trunk, possibly along with oozing brown liquid and chewed fibers. In heavily infested trees, fallen pupal cases and dead adult weevils may be found around the base of the tree.

Posted: 10/4/2010

University of California, Berkeley scientists are enlisting the public’s help in tracking a disease that is killing off oak trees.

For the past two years, scientists have been counting on residents to collect tree samples and send them to the university’s Forest Pathology and Mycology Laboratory. They have used the information to create a map plotting the spread of sudden oak death.

The mysterious pathogen was first discovered in Mill Valley in 1995 and has since killed tens of thousands of trees in northern California and southern Oregon. Scientists estimate the disease, transmitted through host plants and water, could kill as many as 90 percent of California’s live oaks and black oaks within 25 years.

The mapping project, funded by the U.S. Forest Service, is the first community-based effort to combat sudden oak death. It had about 240 participants collecting more than 1,000 samples last year, said Matteo Garbelotto, a UC Berkeley forest pathologist and the nation’s foremost expert on sudden oak death.

“This is part of the solution,” Garbelotto told the San Francisco Chronicle. “If we educate and involve individual property owners, we can make a really big difference.”

Once an infested area is identified, homeowners can remove host trees, which can increase oak survival rate nearly tenfold. Residents also are urged not to do large-scale projects that could disturb the soil and trees during the rainy season because it could help spread the disease.

“Each community that learns they have sudden oak death in their neighborhoods should say, ‘Hey I better do something,’ because by the time you notice the trees are dying, it is already too late,” Garbelotto said.

Click here for a full article on Berkeley’s efforts to track Sudden Oak Death.

Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia. Emerald Ash Borer is also established in twelve other states and parts of Canada. While Emeral Ash Borer is not yet a problem in California, it may be in the future.