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PULLMAN, Wash. – Washington State University researchers have for the first time grown the bacteria in a laboratory that causes Citrus Greening Disease, considered the world's most harmful citrus disease.
Being able to grow the elusive and poorly understood bacterium, Candidatus Liberibacter asiaticus (CLas), will make it easier for researchers to find treatments for the disease that has destroyed millions of acres of orange, grapefruit and lemon groves around the world and has devastated the citrus industry in Florida.
The researchers, including Phuc Ha, postdoctoral research associate, Haluk Beyenal, Paul Hohenschuh Professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, David Gang and Ruifeng He, from WSU's Institute of Biological Chemistry, Anders Omsland, from the Paul G. Allen School for Global Animal Health, and researchers from the University of Florida and University of Arizona, report on their work in the journal, Biofilm.
WSU was selected three years ago for a $2 million U.S. Department of Agriculture grant to study the bacteria, in part, because Washington has no citrus industry. The disease, formally known as Huánglóngbìng, (HLB), is spread by Asian citrus psyllids insects. It attacks the vascular system of citrus trees and causes fruit to become green, misshapen, and bitter-tasting.
A critical step in coming up with weapons to fight the disease is being able to study it in the lab, but the CLas bacterium is notoriously difficult to grow. With a small genome, CLas is thought to depend on very specific nutrient availability and possibly compounds secreted by other nearby bacteria. When researchers used a traditional rich media that they typically use for growing bacteria, they mostly grew bacteria other than CLas.
So, in order to conduct research, scientists have had to get bacterial samples directly from the trees themselves or from the insects that spread it, which is time-consuming and cumbersome. Trying to conduct experiments has also been difficult because, unlike neat lab cultures, bacterial samples gathered from a sick tree vary, depending on where and when the sample is gathered and the level of infection.
Without being able to grow the bacteria in a lab, researchers have been unable to even absolutely confirm that the bacteria, in fact, causes the disease.
In their paper, the researchers for the first time successfully established and maintained CLas bacterial cultures outside of its host.
Using infected citrus tissue as their starting point, the researchers developed a biofilm, a kind of bacterial city that allows a variety of bacteria to thrive. Instead of a rich growth medium that would crowd out the CLas, the researchers severely limited the growth of partner bacteria and created a medium with the specific nutrients, acidity, incubation temperatures, and oxygen levels that are optimal for CLas.
The CLas thrived – an important first step.
“We were really excited,” said Beyenal, “but then we wondered if we could re-grow it.”
The researchers were able to transfer the orange-colored culture and grow new cultures in their biofilm reactors, which they have maintained for more than two years.
“We can do this for as long as we want,” said Beyenal.
Beyenal's group is now working to purify the culture, which will further help researchers to study it. They are also developing genetic-based methods to understand and mitigate the spread of the disease.
- Haluk Beyenal, Hohenschuh Distinguished Professor, Gene and Linda Voiland School of Chemical Engineering and Bioengineering, 509-335-6607, email@example.com.
- David Gang, Professor, Institute of Biological Chemistry, 509-335-0550, firstname.lastname@example.org
- Tina Hilding, communications director, Voiland College of Engineering and Architecture, 509-335-5095, email@example.com
Photo: Phuc Ha and Haluk Beyenal examine a bacterial culture in the laboratory./h2>
hlb culture lab
The California Avocado Society held its 104th Annual Meeting recently and acknowledged an individual's contributions to the avocado industry with its Oliver Atkins Award. This award is presented in honor of nurseryman Oliver Atkins who went beyond what was required or expected, benefitting the avocado industry and its growers. His devotion to the industry was noted in his day-to-day activities and to the changes that he brought to the industry. The award was made to Mr. Pablo Rodriguez.
The award was presented by Nurseryman Rob Brokaw and the following notes were made during the address:
Pablo Rodriguez was born in Mexico in 1950, one of eight kids. He attended a private school on scholarship from ages 8-12, finishing his formal education at 8th grade. He came to the US in order to support his parents and siblings at age 20 in 1971 and worked up and down California for two years before landing at an avocado/citrus nursery in Ventura county.
The nurseryman at the time made a point of “keeping an eye on Pablo”, and Pablo soon rose to be the nursery manger, developing an expertise in grafting. He bought a home in Santa Paula, raising a family there. He gained US citizenship in 1996. He and his family also have a company that performs topworking which is now managed by son Robert.
Readying a rootstock for a graft
As the nursery became involved in working with partners overseas, Pablo's expertise was in demand. He has worked with collaborators in Mexico, Peru, and Dominican Republic, Chile, Florida, Hawaii, Spain, South Africa and more.
His skills and expertise are evident in the millions of avocado and citrus trees that have been produced here in California under his watchful eye, but the greater impact of his efforts resonates around the world.
Pablo and Samuel Garibay showing South Africans the Brokaw Way
Today Pablo is in semi-retirement. In his case, that means he works just as much as he ever did. He's constantly operating in the background shoring up processes and ensuring smooth operations. On Sundays, he can be found wandering the orchards – “just making sure the graftwood is good for harvest this week!” He isn't asked to do this; he just does it because it needs to be done.
But the real story about Pablo, apart from his intelligence and his accomplishments, is his profound humility and humanity. Pablo's dealings with others are informed by a deep spirituality and morality. He seeks to raise others, preferring to remain in the shadows.
Pablo is a guy who, when asked if he can do the impossible, will think for a while, then shrug and say, “Well, it has to be done”. And then does it. This happens regularly.
To his family, to California growers and to the global avocado industry, Pablo has given selflessly of himself. We're all enriched by his presence in our community.
A Serious budman
pablo getting the budwood ready
2019 Date Palm Field Day
November 21, 2019
8:30 - 2:15 PM
Coachella Valley Agricultural Research Station
86501 72nd Ave, Thermal, CA 92274
Fee: $25, lunch included
8:00am – Registration for CE units, coffee, pastries
8:30am- Welcome- Sonia Rios, UCCE Riverside
8:45am- Tom Perring, UC Riverside. Current status of Insect and Mite Pests of dates
9:15am- Tom Perring, UC Riverside. Part 1: What we know about puffy skin of medjool dates
9:30am- Robert Krueger, USDA/ARS. Part 2: What we know about puffy skin of medjool dates/Date research pollination update
9:45- Ali Montazar, UCCE. An update on the on-going irrigation management project in California date palm
10:35- Mark Hoddle, UCR. Updates on the South American Palm Weevil Invasion
11:35- MaryLou Polek, USDA/ARS. Update on Date Palm Activities at the Repository
12:05pm- Lunch- Sponsored by Corteva
1:15pm- Peggy Mauk, UC Riverside.
1:45 - Bob Mulherin, Riverside Agriculture Commission. Laws and Regulation Updates
2:15 – Wrap up
Space is Limited-Register online at:
*No Cash/Check payment will be excepted on site, day of
DPR/ISA Continuing Education Credits Upon Request
The USDA has summarized the US citrus crop for 2018-19 and it is up for both California and Florida, with CA accounting for 51% of US production! But the Florida orange crop is up from last year. This is the state that is getting hammered by huanglongbing amongst all the other demands being made on that industry. This is good news for citrus.
The full report is Here
But the summary is:
Citrus utilized production for the 2018-19 season totaled 7.94 million tons, up 31 percent from the 2017-18 season. California accounted for 51 percent of total United States citrus production; Florida totaled 44 percent, and Texas and Arizona produced the remaining 5 percent.
Florida's orange production, at 71.8 million boxes, is up 59 percent from the previous season.Grapefruit utilization in Florida, at 4.51 million boxes, is up 16 percent from last season's utilization. Florida's total citrus utilization increased 56 percent from the previous season. Bearing citrus acreage, at 387,100 acres, is 13,800 acres below the 2017-18 season.
Utilized citrus production in California increased 15 percent from the 2017-18 season. California's all orange production, at 49.8 million boxes, is 13 percent higher than the previous season. Grapefruit production is down 16 percent from the 2017-18 season but tangerine and mandarin production is up 35 percent. Utilized production of citrus in Texas is up 29 percent from the 2017-18 season. Orange production is up 33 percent from the previous season and grapefruit production increased 27 percent. Total citrus production in Arizona's lemon production is up 35 percent from last season.
The value of the 2018-19 United States citrus crop increased 1 percent from last season, to $3.35 billion (packing house-door equivalent). Orange value of production decreased 7 percent from last season and grapefruit value is down 1 percent.
Tangerine and mandarin value of production is 31 percent higher than last season but lemon value of production is down 4 percent.
Overall comparisons discussed above are based on similar fruit types. The revised production and utilization estimates are based on all data available at the end of the marketing season, including information from marketing orders, shipments, and processor records. Allowances are made for recorded local utilization and home use. Estimates for the 2018-19 California Valencia oranges and grapefruit are preliminary.
BUT, the latest news from the Central Valley navel forecast is that it is down,
The 2019-20 California navel crop is down 7% from last season, according to the first U.S. Department of Agriculture estimate.
With harvest expected to begin in October, the California navel forecast is 76 million (40-pound) cartons, down 7% percent from the previous year, the USDA said Sept. 12.
Farming is a roller coaster.
Ambrosia beetles, which are a large group of several thousand species worldwide, belong to the bark beetles. All species are characterized by the ability to cultivate fungi. Invasive Shot Hole Borers that attack avocado and a range of native and landscape trees in California and the Laurel Wilt Disease that hammers avocado in Florida are ambrosia beetles. These beetles cultivate fungi in living trees and over time, the fungus is what kills the tree.
Beetles share the work of cultivating their fungal gardens: some clean the tunnel systems that are being eaten into the wood; others clear the dirt from the nest and clean their fellow workers -- always with the aim of optimizing the symbiosis of beetle and fungus.
It's been long known that alcohol is produced by weakened trees and that these trees are recognized and colonized by the beetles. Traps baited with alcohol are used to catch the catch the insects when they fly. Alcohol is very attractive to the beetles in large part because the fungi they feed on performs best in an alcohol-rich environment. Alcohol is normally used as a preservative to impede other fungi, such as molds from growing, and this is the case for the fungi associated with these beetles. They prefer to grow in an environment where other fungi don't grow.
Here's an interesting article showing how this preference by disease-causing fungi allows them to thrive in a normally harsh environment. Maybe it can be exploited.
Christopher M. Ranger el al., "Symbiont selection via alcohol benefits fungus farming by ambrosia beetles," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1716852115
Photo: Party Beetles
Credit: Gernot Kunz