Fusarium Dieback / Polyphagous Shot Hole Borer

Recently a new beetle/fungal complex was detected on avocado and other host plants in Los Angeles, Orange and San Bernardino Counties. The two fungal species are Fusarium euwallaceae and Graphium sp., which form a symbiotic relationship with a recently discovered beetle that is commonly known as the polyphagous shot hole borer (PSHB, Euwallacea sp.)

Together, they cause the disease Fusarium dieback (FD). When the beetle burrows into the tree, it inoculates the host plant with the fungus (Fig. D), which is carried in its mouthparts in a structure called mycangia.

The fungus attacks the vascular tissue of the tree, blocking the transport of water and nutrients from the roots to the rest of the tree, and eventually causing branch dieback. The beetle larvae live in galleries within the tree and feed on the fungus.

FD has been observed on more than 110 different plant species in California, including many species common in urban landscapes and on such agriculturally important species as avocado, olive and persimmon.

Symptoms: Each host species shows different symptoms depending on the response to infection. Sycamore, box elder, maple, red willow, and castor bean are good trees to search for signs and symptoms of the beetle, as it tends to prefer to infest these hosts first. Depending on the tree species attacked, PSHB injury can be identified either by staining, gumming, or a white-sugar exudate on the outer bark in association with a single beetle entry hole.

The vector beetle: An exotic ambrosia beetle (Euwallacea sp.) is very small and hard to see. At the advanced stage of infestation, there are often many entry/exit holes on the tree (Fig. E-F). Females are black and about 1.8 – 2.5 mm (0.07-0.1 inch) long (Fig. A-B (right)); males are brown colored and about 1.5 mm (0.05 inch) long (Fig. B ((left)). The entry/exit hole is about 0.85 mm (0.033 inch).

What to do:

Look for a single entry/exit hole surrounded by wet discoloration of the outer bark
Scrape off the bark layer around the infected area to look for brown discolored necrosis caused by the fungus.
Follow the gallery to look for the beetle (may or may not be present).
Avoid movement of infested firewood and chipping material out of infested area.
Look for other hosts (Castor bean, sycamore, maple, coast live oak, goldenrain, liquidambar) showing symptoms of the beetle/disease.
Sterilize tools to prevent to spread of the disease with either 25% household bleach, Lysol® cleaning solution, or 70% ethyl alcohol.

Who to contact if you find the problem: If you suspect that you have found this beetle or seen symptoms of the Fusarium dieback on your tree please contact either your local farm advisor, pest control advisor, county Ag Commissioner office or Dr. Akif Eskalen by either phone 951-827-3499 or email at akif.eskalen@ucr.edu.

For more information visit www.eskalenlab,ucr.edu.

Patrick Cavanaugh2016-05-31T19:35:24-07:00June 18th, 2014|

UC Researchers Trying to Understand Roll of Green Waste and Manure

Almond Growers Are Asked to Return Survey

Researchers are trying to find out the benefit of adding green waste from animal manure and adding it to the soil of permanent crops, and they are looking for information from local growers.

A team of UC Davis and UC Merced researchers are trying to find how and why fruit and nut growers are using organic matter amended to their soils. These amendments might include green waste composted or non composted animal manure.

The goal of this survey is to help develop better approaches so the organic matter amendment can be used more safely, according to Daniel Schellenberg, postdoctoral scholar at UC Davis, who is the coordinator of the project.

“We’re hoping to find out the benefit to the orchard for using these types of materials and how they might improve environmental quality but as well as to find out are they benefit tree nutrition are they changing the biology in the soil, or they simply increasing the capacity of the soil to hold water.” said Schellenberg.

All California almond growers will be getting a survey in their mailboxes this week.

“We’re working with in partnership with the Almond Board of California we were able to have a mailing that will go out to almond growers about their practices and have also built a website that will allow all growers of trees, fruits, and nuts to be able to take the survey.” said Schellenberg

The survey can be found here.

Previously, the Almond Board of California stated that growers should not use these amendment due to food safety, but there has been no field trials to show the risk. A research goal is to find how amends can be used safely, and to determine how much nitrogen certain amendments can provide for tree and vines.

Patrick Cavanaugh2016-05-31T19:35:27-07:00June 10th, 2014|

Housing Market Recovery Helps Timber Producers

Source: Steve Adler; Ag Alert

Home construction in California is on the upswing as the housing sector slowly recovers from the dramatic downturn of the recession that saw home prices and new construction plummet.

Going hand in hand with the increase in home building is the demand for lumber for framing, moldings, doors, fences and other uses. California timber producers say they welcome the increased demand for lumber, but are held back by the regulatory climate in the state that cuts into their bottom line.

As a result of added costs and restrictions on timber harvest, California forestry owners say they have difficulty competing with their counterparts in Washington, Oregon and British Columbia who work in a more business-friendly climate.

An estimated two-thirds of the building materials utilized in California comes from the Pacific Northwest and Canada’s westernmost province.

“Lumber production in California has dramatically fallen off from where we were a couple decades ago,” said Mark Pawlicki, director of corporate affairs for Sierra Pacific Industries in Anderson. “We are harvesting around 1.4 billion board-feet of timber now in California, and that is less than half of what it used to be. A lot of the fallout has been because of the reduction in sales of timber in national forests. It is a combination of regulations involved and a philosophical change within the U.S. Forest Service that occurred back the 1990s.”

Timber owner Peter Bradford of Booneville, who serves as board liaison to the California Farm Bureau Federation Forestry Advisory Committee, said the high cost of regulations “adds a substantial amount” to the price of California timber.

“We are very over-regulated when compared to Washington, Oregon or British Columbia,” Bradford said. “There is a lot of material that comes in from Oregon and Washington because the cost to get a harvest plan to log the trees is easier and much less costly than it is here. It is time, paperwork and cost here in California.”

Despite these challenges, timber owners in California say they are more optimistic than they were a few years ago, when the market for timber had decreased significantly.

“Prices right now aren’t the greatest, but they are better than they were five years ago. For some of the redwood that we are selling this summer, we’ve been given a price of around $900 for 1,000 board-feet. Back in the heyday of the late 1990s, we were receiving $1,500 for that same amount of lumber,” Bradford said.

Pawlicki noted that lumber is a cyclical market.

“As everyone knows, housing construction has been way off in recent years, but it has been gradually coming back. We have seen improvements in U.S. housing construction and along with it improvements in lumber pricing,” he said.

There are currently about 30 lumber mills in California, a decline of 80 mills since the 1990s.

“With the downturn that we experienced in lumber demand, a lot of sawmills closed in California and we are roughly in balance now with supply and demand,” Pawlicki said. “As demand goes up, we expect to see some pricing increases for lumber—not dramatic, but nevertheless steady. And that helps us to maintain our industry here in California.”

Producing more lumber in California to meet the state’s demand, he said, would require “some significant changes in the regulatory world.”

“Folks are not too inclined to build a new sawmill in this state with the regulatory environment that we have,” he said.

Another concern is the tight labor supply, particularly for employees who are experienced in timber harvest and millwork.

“Labor is a tremendous issue in the timber industry right now, trying to get people who are able to do the work,” Bradford said. “This is frequently something you are born into and you know how to do it.”

The labor shortage is felt most acutely in the mills, according to Pawlicki.

“We are experiencing some difficulty filling jobs, particularly millwrights and technical folks in our mills. These mills now are very technical and computerized systems for sawing lumber. It requires a different skill-set than what was required in the past,” he said.

The California drought creates concerns for foresters for several reasons, including increased fire danger and a slowdown in tree growth that corresponds to the lack of water for the trees’ root systems.

“The drought stresses the trees and we will see some tree die-off. We are concerned that we may lose a lot of trees to drought—and when that happens, insect infestations occur and that kills even more trees, and this creates an increased concern for catastrophic wildfires,” Pawlicki said.

Bradford said wildfire concerns also build because of the problems that small landowners face in trying to harvest their timber.

“The amount of environmental review that they have to go through to get a timber harvest permit and the cost to get that review done, with the market value of timber now, makes it economically undesirable. As a result, some of these properties are being sold for home sites. With this increased population comes an increase in the fire danger,” he said.

Bradford said he has seen a buildup in understory in the forests—shrubs, bushes and grasses—that has created dangerous fire conditions.

“That is the worst part of it. The other thing, of course, is that without the normal amount of rainfall, the trees won’t grow as fast as usual. But that is something that is pretty hard to measure,” he said.

Despite the ongoing challenges facing the timber business, Pawlicki noted some positive signs.

“We are optimistic that the market is going to improve domestically. We are seeing some improvements in operating conditions in California, and we are seeing some improvements in the legislative and regulatory front that have helped us,” he said.

Patrick Cavanaugh2016-05-31T19:35:27-07:00June 9th, 2014|

Tree-killing bug invades Southern California

Source: Amina Khan; Los Angeles Times

Akif Eskalen steps through the dense, damp leaves in a wooded neighborhood, scrutinizing the branches around him. He’s looking for evidence of an attack: tiny wounds piercing the bark and sap dried around them like bloodstains.

The victims are box elders, sycamores and coast live oaks, all in some state of suffering. Eskalen approaches a tree riddled with 1-millimeter holes, as if someone used it for miniature target practice. It’s time to nab a perp. He selects a hole, pulls out a large knife and expertly levers out a chunk of wood.

There, in his hand, is a glossy beetle no larger than a sesame seed: the polyphagous shot hole borer.

Though small and sluggish, its appetites are wide and its spread is relentless. It attacks forest trees, city trees and key agricultural trees. It has defied all conventional and chemical weapons. No one seems to have a way to stop it.

This cul-de-sac, in the foothill community of Pasadena Glen, has been particularly hard-hit. One giant tree was so weak that one of its trunks toppled from one resident’s yard across a creek and crashed into a neighbor’s. Another tree was filled with green jelly, its insides completely digested.

Anxious residents cluster around as Eskalen examines a wounded sycamore.

“We’ve got a canyon full of highly educated people who want answers,” said longtime resident Linda Williams, a retired business owner.

Eskalen, a plant pathologist at UC Riverside, wants to contain this invasive bug before it spreads throughout Southern California. Already the beetle has been sighted as far south as San Diego, as far west as Santa Monica, as far east as the Riverside County city of Eastvale.

Eskalen tips the beetle into a glass vial. He detaches a pink spray bottle from his backpack and administers a few lethal squirts of ethanol before twisting the vial shut.

These beetles have a strange M.O. They don’t eat wood, like termites; instead, they drill circular tunnels toward the heart of the tree. They carry fungal spores in their mouths and sow them like seeds as they go.

Then they harvest the fungus to feed their larvae. It’s a deadly partnership: The beetles attack, but the fungus also helps to kill, colonizing the wood tissue and spreading through the plant.

The beetles have easily evaded the authorities. Inside the tree, they’re well protected from pesticide sprays. The incestuous offspring mate with their siblings inside the trunk, so sex pheromones do not lure them out.

“If we can’t control them,” Eskalen said, “they are going to wipe out all our trees.”

Eskalen’s first contact with these devious bugs was in 2012, triggered by a desperate email from South Gate resident Chelo Ghaly. The real estate closer’s avocado tree had been oozing white spots all over its trunk.

Local gardening authorities were of no use. Suggestions to try fungal sprays failed. Frustrated, she scoured the UC Riverside website and found Eskalen, who studies avocado diseases. She sent him pictures of the damage.

Eskalen said he looked at the strange symptoms and grabbed his car keys.

After examining the fungus in Ghaly’s tree, he took his findings to the California Avocado Commission. To date, they’ve given UC Riverside scientists a total of $800,000 to broaden his investigation into this mysterious species of ambrosia beetle.

His survey came to a head when he reached the Los Angeles County Arboretum and the Huntington Botanical Gardens — two repositories of healthy, well-kept trees.

They’re not so healthy anymore.

At the Huntington in San Marino, Eskalen spied a diseased specimen. He hopped up, grabbed a high branch with both hands and bounced until it snapped off.

“Ach, Akif, really?” said Tim Thibault, the Huntington’s curator of woody collections. It didn’t matter: The plant was probably a goner.

Such pests typically feast on a small group of plants. But this one doesn’t seem to discriminate.

When Eskalen and his colleagues surveyed the 335 species at the Huntington and the Arboretum, in Arcadia, they found the beetle had attacked 207 of them and 54% of these victims were infected with fungus. Nearly two dozen of the trees were being used as reproductive hosts — places where the beetles can raise their brood.

The consequences of a wide-ranging infestation could be enormous. Common city trees, such as American sweetgum and maple, would become public branch-dropping hazards. Native trees such as the California sycamore and the coast live oak have started to succumb, creating a fire risk in the form of dead, dry tinder. Avocados and other crops could face huge financial losses.

Like any good forensic investigator, Eskalen is using DNA to crack the case. He started by sequencing the fungi from diseased trees and found there were three different species — two that may serve as food and one that may act as protection by fighting off competing plant pathogens.

He also enlisted UC Riverside entomologist Richard Stouthamer to examine the DNA of the beetles themselves. Stouthamer’s genetic analysis traced the bugs to Vietnam.

Experts aren’t sure how the beetle made its way to the U.S. Invasive species around the world are moved on human cargo, in clothes, in wooden shipping pallets and in boats’ ballast water.

The beetles are not as much of a pest in Asia — perhaps because some other critter keeps them in check. Maybe that natural enemy could be brought to California to fight the infestation, a practice known as biological control.

In March, Eskalen, Stouthamer and Thibault spent two weeks in Vietnam, searching forests and fields for these natural vigilantes. They collected a host of possible allies, whose DNA is being analyzed in the lab.

“I am very hopeful that we are going to find some solutions to control this fungus,” Eskalen said. “We have to.”

Thus far, what little is known about the polyphagous shot hole borer doesn’t place it in the alarm-raising category of the Mediterranean fruit fly or the Japanese beetle, which some say spread more quickly. The U.S. Department of Agriculture hasn’t imposed any restrictions to contain this beetle.

Still, Eskalen and others fear a worst-case scenario if not enough is done to contain the pest. The number of tree species attacked by the beetle now stands at 286.

Even as the Vietnam-related infestation spreads, Stouthamer’s genetic fingerprinting linked the incursion in San Diego to a different population in Taiwan.

While scientists try to get a handle on the situation, residents like Ghaly are struggling with the pest on their own.

Ghaly had been keeping the tree alive at Eskalen’s request. But as her tree worsened, she thought about her elderly mother cleaning up after the failing plant. There were also signs that the infestation in her neighborhood was spreading.

She couldn’t wait any longer. Early this year, she had it chopped down.

Patrick Cavanaugh2016-05-31T19:35:27-07:00June 7th, 2014|

Record Crowd of Tree Nut Growers in Turlock

Big Crowd in Turlock for Tree Nut and Vine Expo

More than 800 growers and PCAs were at the Stanislaus County Fairgrounds TODAY, to hear from many speakers, visit with hundreds of exhibitors, talk about tree nuts and grape vines, and enjoy breakfast and a barbeque Tri-Tip lunch.

“It was the 18thannual event and with a record crowd. All growers were upbeat following a good harvest and good nut prices. Also, both domestic and export sales are increasing,” said Patrick Cavanaugh, editor of Pacific Nut Producer magazine and co-host of the event.

Exhibitors speak with tree nut growers about products and services

“We are pleased that both the nut and grape industry are doing well in California. All we really need is a lot of rainfall this winter,” said Dan Malcolm, publisher of Pacific Nut Producer as well as American Vineyard magazine, and co-host of the show.

Crowd gathers outside to look over equipment.

Speakers came from UC Davis, Stanislaus County Ag Commissioner’s office, UC Cooperative Extension, Almond Board of California, California Walnut Board, Stanislaus County Farm Bureau, and CalAgSafety.

“We appreciate the support of the event sponsors and the record number exhibitors,” said Cavanaugh.

Ryan Genzoli with Cal Ag Safety speaks.

Sponsors Included: