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A foreboding fungus is threatening orchards in the San Joaquin Valley

A fallen almond tree that was weakened by Ganoderma fungus. (Photo: Bob Johnson)
When an almond tree keels over in a mature orchard, it could be a sign of something ominous. UC scientists are tracking a fungal infection in San Joaquin Valley almond trees that can cost farmers hundreds of thousands of dollars in lost production.

Ganoderma's been around for a long time,” said Bob Johnson, a UC Davis graduate student who is leading the study for his doctoral thesis under the direction of UC Davis plant pathologist Dave Rizzo. “The tree failure we're seeing may be that we've now reached such a density of almonds here, that the problem just seems more widespread. Or it may be a new Ganoderma species in our state.”

The UC Cooperative Extension nut crops advisor in Fresno County, Mae Culumber, speculated that air quality regulations prohibiting the burning of orchard prunings may have allowed fungi to grow in slash piles in agricultural areas. However, the cause of the problem is currently unknown.

Ganoderma is a genus of fungi with about 80 known species. It is typically considered a forest pest in the U.S. and, in terms of agriculture, poses problems for the palm tree industry in the tropics. The Ganoderma now being found in California agriculture grows in the living heartwood of almond, peach and other stone fruit trees. The presence of the fungus doesn't appear to impact tree production. The only outward sign is development of rather large shelf-like mushrooms on the trunks called conks.

“Once you see conks on the tree, it is essentially dying from the inside out,” Johnson said. “The conks release trillions of spores which wind and water move through the orchard and to neighboring orchards. It's next to impossible to stop the spread.”

A farmer in Hanford recently pulled out and destroyed every tree in his 120-acre orchard because of Ganoderma infection.

“This was a 9- or 10-year-old orchard, just when the grower starts making money after investing in its establishment,” Johnson said. “Instead, his trees were just falling down right and left and he pulled out the orchard.”

Culumber called Johnson out to a Fresno County orchard where the farmer is starting to lose trees.

“In his orchard, every fifth tree has a massively sporulating conk,” Johnson said. “Growers see the conks, but they don't realize they are the infectious part of Ganoderma fungi.”

Culumber said other orchards in the area also have active conks.

“I know of at least two locations within a square mile,” she said. “One is very progressed, and I talked with another grower with early symptoms.”

Johnson is calling on farmers to contact him if their trees have fallen over due to decay in the trunk or if they have seen conks on tree trunks.

“We need to understand the distribution and incidence of Ganoderma infection in order to develop management strategies that will limit the impact of this disease,” Johnson said.

To report trees potentially infected with Ganoderma, contact Johnson at (530) 302-6301 or bobjohnson@ucdavis.edu.

A collage of tree trunks with Ganoderma conks. Once the conks appear, the tree is dying from the inside out. (Photos: Bob Johnson)
Posted on Tuesday, January 17, 2017 at 9:40 AM
Tags: Bob Johnson (1), Dave Rizzo (1), Ganoderma (1), Mae Culumber (1)

In a new study biochar helps yields, but only in the short term

Adding biochar to a farm's field is an irreversible decision, so understanding its long-term impacts is essential for farmers to make informed decisions.

Biochar, a charcoal created from organic materials burned at high temperatures and added as a soil amendment, has been shown to increase pH and soil fertility in areas with more weathered, acidic soils, like the tropics. But a new study shows its impact on productive soils like those in California's Central Valley may be quite different.

Findings from a four year study conducted at the Russell Ranch Sustainable Agriculture Facility at UC Davis showed an increase in corn yields in the second year after adding biochar, but through different means than have been observed elsewhere.

The study, published in the journal Agriculture, Ecosystems and Environment, used biochar made from walnut shells, cooked at 900°C from an orchard in Winters, Calif. Biochar was added to a plot rotating tomato and corn crops at the Russell Ranch Sustainable Agriculture Facility at UC Davis, a long-term research facility focused on using farm management practices similar to those used at commercial farms.

Ph.D. candidate Deirdre Griffin at a research plot at the Russell Ranch Sustainable Agriculture Facility

Short term boosts in yields

“A lot of biochar lab studies look at intricacies of how biochar changes nitrogen cycling, so I was very focused on looking at that in the field,” says Deirdre Griffin, Ph.D. candidate in soils and biogeochemistry at UC Davis and lead author of the study.

But instead of a change in the nitrogen cycle, the biochar affected potassium, phosphorous, and calcium in the soil, causing an 8 percent increase in corn yields. The increase, however, didn't happen until the second year after application.

That delay may be due to biochar's hydrophobic nature — it repels water when first in the ground, and may only start to interact with soil after significant time. After year two, the yield benefits of biochar dropped off, and by year four showed no difference compared to plots without biochar.

“The benefits that we saw were from direct fertilization from biochar, in which case growers might be able to see the same boost in yield if they applied a little more fertilizer,” says Griffin. “We didn't see much change in the soil properties that could have more lasting effects. But those things could still be impacted in the coming years as the biochar continues to age.”

To see continued yield increases like these, growers may need to apply biochar regularly, which is not its intended purpose and may pose challenges for growers. Biochar can be dusty, dispersing black soot as it is applied. Growers can wet biochar to limit its dust, but without overcoming that challenge, repeatedly adding biochar to the soil may limit its appeal.

Many biochars, many functions

Like compost, different biochars act differently in the soil. Different sources (type of shell or other organic material), treated at different temperatures, and added to varying soil types can all impact what benefits a grower may see from biochar.

Carbon sequestration, not included in this study, is broadly understood as a benefit of biochar, and some research is looking at its potential to pull heavy metals from soils.

“When biochar research started flourishing, people started seeing positive results in tropical systems and got excited about it,” says Griffin. “Because of our soils and agriculture, we don't necessarily see the same benefits in our systems. But every biochar is different, and we need to understand their characteristics, to engineer them for different systems and different purposes. And we're still working to understand that.”

Griffin's study is ongoing and Russell Ranch and will continue to provide insights on biochar's impacts over time.

Having a long-term study that uses realistic farm practices will help build the understanding of the role of biochar in already fertile soils, and have strong data showing how biochar really acts in the long run, so farmers making the irreversible decision to add biochar know exactly what they are investing in.

More information on biochar can be found on the UC Division of Agriculture and Natural Resources' Biochar Blog, the Solution Center for Nutrient Management, and the Biochar Database managed by associate professor Sanjai Parikh at UC Davis.

Posted on Wednesday, January 11, 2017 at 8:47 AM

Grass-fed beef production a possible money-maker for Central California ranchers

The health benefits of grass-fed beef are well documented. Meat from cattle that live out their lives grazing on rangeland before being processed has more beta-carotene, vitamin E and omega-3 fatty acids than the meat from animals finished at feed lots.

The health benefits – and for some consumers, the idea that cattle raised on the range have longer, happier lives than conventional beef cattle – increases the value of the product. Grass-fed beef generally sells for 60 percent more per pound than standard beef. These potential premium prices get cattle ranchers' interest, and therefore captured the attention of UC Cooperative Extension rangeland advisor for Mariposa and Merced counties Fadzayi Mashiri.

Ranchers pose with Rebecca Ozeran, UCCE livestock advisor in Fresno and Madera Counties (green blouse), and Fadzayi Mashiri, UCCE livestock advisor for Mariposa and Merced counties (red sweater.)

Two major challenges face ranchers who wish to produce grass-fed beef: the lack of local processing plants, and the unfamiliar marketing strategies that successfully selling a niche product demands.

“I decided to bring ranchers together to discuss these issues,” Mashiri said. She formed a group that meets regularly in Mariposa County to discuss how they might be able to work as a team to break into the grass-fed beef market. Mashiri sees this project as an opportunity for the ranchers to diversify their sources of income and increase profit margins.

“Farm to fork is getting big,” said Marshall Long, a Mariposa County supervisor and rancher who attended the meeting this fall. “I want to keep those value-added dollars in the county.

Most of the ranchers in the valley and foothill counties of Merced, Mariposa, Madera and Fresno have cow-calf operations. After calves are born on the range, they stay on the land for about a year before being sold at auctions and fed grain or other high-carbohydrate feeds in feedlots. In grass-fed production, yearlings aren't sold, but rather kept on the land for another two years before they are processed.

Cattle grazing in Mariposa County.

The meat can be quite different. Grass-fed cattle produce meat with a distinctive flavor, less marbling, and a yellow cast. And, it commands a higher price.

'Made in Mariposa' marketing brand.
Mashiri invited Tara Schiff, the grant coordinator with the Mariposa County Chamber of Commerce, to the recent grass-fed beef planning meeting. Schiff spearheaded the development of a “Made in Mariposa” marketing brand. The initiative has more than 100 members, including local producers of vegetables, cider and wine.

“We have strength in numbers,” Schiff said.

Made in Mariposa is a potential marketing partner, or represents a model for local beef producers to emulate.

“If we think big, how big do we want to be?” Mashiri asked. “Can we work together to relieve individual producers of the pressure of selling on their own?”

The producers concluded that their next step would be a market study to determine whether stores and restaurants would be willing to pay for a ready supply of grass-fed beef. Schiff of Made in Mariposa and Mashiri will identify grant opportunities that would allow the group to move forward with the study.

Under Mashiri's leadership the ranchers will come together again in the spring to continue their planning work together to increase their businesses' bottom lines by diversifying into the production of a specialty meat product.

Ranchers confer after the Mariposa meeting.
Posted on Monday, December 19, 2016 at 9:46 AM

Weather radar helps researchers track bird flu

This NEXRAD map shows where migrating waterfowl are gathered in rice fields, herbaceous wetlands and other agricultural land.

The same weather radar technology used to predict rain is now giving UC researchers the ability to track wild birds that could carry the avian influenza virus. Avian influenza, which kills chickens, turkeys and other birds, can take a significant economic toll on the poultry industry. In 2014- 2015, the United States experienced its worst bird flu outbreak in history, resulting in more than 48 million birds dying in 15 states, including California. 

“We use the existing network of weather radar stations in the U.S. in the same way that radar is used to track rain, except that we process the data to allow us to interpret the radar signal bouncing off birds instead of raindrops,” said Maurice Pitesky, UC Cooperative Extension poultry specialist. “The data can be interpreted to track birds.” 

Migrating waterfowl, such as Canada geese and common egret, could carry the avian influenza virus.
NEXRAD, or next-generation radar, is a network of 160 high-resolution S-band Doppler weather radars operated by the National Weather Service. The technology works best for tracking birds in the winter during feeding. When waterfowl leave their roosting locations in concert to feed, their bodies produce reflectivity of the radar beam.

“By tracking mass bird movements remotely in real-time, we hope to gain novel strategic insights with respect to surveillance and prevention of avian influenza transmission to domestic poultry,” said Todd Kelman, a veterinarian and engineer who co-leads the project with Pitesky, who is also in the School of Veterinary Medicine at UC Davis. They are exploring how the information might be used to prevent an outbreak.

In California, waterfowl migrate by the millions from September through March via the Pacific Flyway, where they winter in wetlands, rice and corn fields. The Central Valley alone is home to 3 million waterfowl at the height of migration.

“Using NEXRAD and various other approaches, we hope to be able to produce monthly or quarterly maps that will alert poultry producers as to the locations of waterfowl in the Central Valley of California,” Pitesky said. 

This Landsat map shows wetland coverage in the Sacramento Valley in 2007, a rainy year, and 2015, a dry year.

“Waterfowl populations can have different habitat based on the amount of precipitation in a given year,” said Pitesky. “Therefore, we need to use these types of monitoring tools to understand where waterfowl are located. Landsat, or satellite-based land imagery, and NEXRAD are two remote tools that may be very useful, as opposed to flyovers and banding, which are more expensive and not practical for large geographical areas.” 

The project — funded by UC Agriculture and Natural Resources — is a collaboration between UC Davis School of Veterinary Medicine and Jeff Buler, University of Delaware wildlife ecologist whose team first developed the NEXRAD approach in the Central Valley of California. They are also working with the U.S. Geological Survey, the California Department of Food and Agriculture, the California Poultry Federation, the Pacific Egg and Poultry Association and Point Blue, an organization that focuses on conservation science.

Posted on Wednesday, December 7, 2016 at 11:37 AM

Wild horse over-population is causing environmental damage

Most Americans envision healthy mustangs galloping free on the range when they think about the country's wild horse population. But UC Cooperative Extension rangeland advisor Laura Snell sees another image.

Wild horses are beautiful, but present land management challenges.

In conducting research on the over-populated wild horse territory at Devil's Garden Plateau in Modoc County, she witnesses a group of horses visiting a dwindling and damaged pond.

“Maybe there is enough for the lead stallion and the lead mare to drink. The rest stand there and look longingly at the diminished water source,” Snell said. “They do not seem content.”

The research Snell has underway at Devil's Garden was chronicled in the current issue of California Agriculture journal by executive editor Jim Downing. The federal government has determined the ideal horse population on the 230,000 acres of wild horse territory is no more than 402, however, more than 2,000 wild horses are running on the land.

Snell began working in the remote northeast corner of California in 2015.

“I had Modoc County ranchers coming up to me on my second day of work asking me how to solve the wild horse issue,” she said.

She realized that agencies and authorities responsible for policies that determine the horses' fate, and advocates who lobby strongly that the horses should be cared for humanely, don't see the poor conditions suffered by the horses and the environmental degradation of the land.

“The area is a quarter million acres in size. There are no main roads, so you have to take ATVs to see the horses,” Snell said. “We realized we needed to provide visuals to show people the horses and what the landscape looks like due to unmanaged grazing by the wild horses.”

Snell places wildlife cameras for two-week periods near 24 remote water sources in wild horse territory in Modoc and Lassen counties. At each site, the camera takes a burst of three pictures automatically every 15 minutes; motion detectors on the cameras also trigger a shot whenever an animal enters the field of view.

Laura Snell, left, and USFS rangeland management specialist Jenny Jayo mount a wildlife monitoring camera at Bottle Springs, a water source in Modoc National Forest. (Photo: Will Sukow)

Preliminary data from 2015 show some striking findings. At one spring site, for instance, more than 71 percent of all animals detected over the sampling period were horses. Cattle accounted for 19 percent and the rest were pronghorn antelope, deer and hawks. The study will continue through 2017.

Wild horses are running in the Devil's Garden territory, and outside the territory, on private and tribal land. Fences don't hold the horses in, Snell said. Federal wild horse management areas are intended for multiple uses, including livestock grazing, hunting, and wildlife habitat. But in Devil's Garden, livestock have been excluded because of the environmental degradation.

“It was never intended to be single use area,” Snell said. “The horses are gorgeous animals, but I also like to see pronghorn, elk and mule deer. Some groups of wild horses are getting large and studs are getting aggressive. I know people who no longer ride their personal horses because it's not really safe with the territorial nature of the stallions.”

The images and data from Snell's research are designed to inform management and policy decisions in hopes of easing the expensive and environmentally harmful wild horse over-population. Already U.S. Representative Doug LaMalfa (R-Oroville) has brought the study to the House Committee on Natural Resources and preliminary results have been shared with Bureau of Land Management's Wild Horse and Burro Advisory Board.

Wild horse impacts near Bottle Springs in the Modoc National Forest. (Photo: Will Sukow)
A herd of horses visits a spring at the Devil's Garden Wild Horse Territory. (Photo: Laura Snell)
Posted on Tuesday, December 6, 2016 at 1:18 PM
Tags: Laura Snell (1), rangeland (12), wild horses (1)

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