Pests and Diseases

Detection of Huanglongbing Triggers Quarantine in Ventura County; First HLB Detection in County

Courtesy of Citrus Insider

The California Department of Food and Agriculture (CDFA) has declared a quarantine in Ventura County following the detection of the citrus disease Huanglongbing (HLB), or citrus greening, in two citrus trees on one residential property in the city of Santa Paula. These detections are the first HLB-positive trees in Ventura County. CDFA is working with the United States Department of Agriculture and the Ventura County Agricultural Commissioner on this cooperative project.

The disease was detected in plant material taken from one orange and one lime tree in a residential neighborhood in the Santa Paula area of Ventura County. These detections follow the confirmation of a Candidatus Liberibacter asiaticus (CLas)-positive Asian citrus psyllid (ACP) sample taken from the find site.

CDFA crews will be working to remove and dispose of the infected trees and are conducting a mandatory survey of every property within 250 meters of the detection site. After the survey is complete, all host plants in the 250-meter area around the detection site will be treated to suppress the disease vector, the ACP. By taking these steps, a critical reservoir of the disease and its vectors will be removed, which is essential to protect the surrounding citrus from this deadly disease.

These detections establish a mandatory five-mile citrus HLB quarantine area around the find site. The quarantine area is bordered on the north by Ojai Road; on the south by E Los Angeles Avenue; on the west by Wells Road; and on the east by Balcom Canyon Road. The quarantine prohibits the sale of all host nursery stock and the movement of all host plants or plant parts within a five-mile radius of the finds. The quarantine applies to residents and commercial operations alike. These detections will also place parts of Ventura County into Bulk Citrus Regional Quarantine Zone 6, which will require any commercial citrus growers to apply an additional mitigation step(s) to move fruit within or from this zone. Production and retail nurseries within the five-mile quarantine are being contacted by CDFA and will be issued a hold notice preventing the sale of nursery stock host plants. Visit CDFA’s Map and Quarantines page for more details.

Growers in Ventura County should contact Grower Liaisons Sandra Zwaal at szwaal2@gmail.com or Cressida Silvers at cressidasb@gmail.com for additional information about these detections. In response to the HLB detections in Santa Paula, a grower meeting is being held on Wednesday, Oct. 4. Stay tuned to Citrus Insider for details or reach out to the Grower Liaisons for more information.

An HLB quarantine area currently exists in parts of Los Angeles, Orange, Riverside, San Bernardino and San Diego counties, where more than 6,300 residential trees have tested positive for the disease and have been removed.

To read the full press release, please visit the CDFA website.

California Ag Today2023-10-04T08:09:53-07:00October 4th, 2023|

Asian Citrus Psyllid Study: Vigilance Urged but ‘No Cause for Panic’

By Mike Hsu, UCANR

Preliminary results indicate 3.5% of ACP collected showed signs of bacterium that can cause huanglongbing

An ongoing study in the commercial citrus groves of coastal Southern California is looking at whether Asian citrus psyllids – the insect vector of huanglongbing “citrus greening” disease – are carrying the bacterium that can cause HLB.

Thus far, the project has tested more than 3,000 adult ACP collected from 15 commercial citrus sites across the region, of which 138 – just over 3.5% – had some level of the bacterium present, according to researchers from UC Agriculture and Natural Resources, UC Davis, UC Riverside and the University of Arizona, Tucson.

“While the results are a cause for concern, the situation in California is much better than in Florida and Texas, where ACP carrying the bacterium make up the majority of the population and HLB is widespread in commercial citrus,” said Neil McRoberts, a UC Davis plant pathologist and UC Integrated Pest Management program affiliate advisor. “The results indicate that there is no room for complacency, but also no cause for panic.”

Since the first HLB-infected tree in California was found in 2012, nearly 4,000 infected trees have been detected and removed from residential properties in Southern California, mainly in Orange and Los Angeles counties. According to McRoberts, “to date, no HLB has been found in commercial citrus” in California.

He stressed, however, that the aforementioned ACP study – funded by the HLB Multi Agency Coordination Group and managed by USDA-APHIS – does not involve any testing of trees for HLB and focuses only on looking at the insect which spreads the bacterium.

McRoberts also emphasized that the project’s detections of the bacterium cannot be considered “official” because the researchers’ lab procedures differ from the official testing protocols of the California Department of Food and Agriculture.

“Follow-up sampling by CDFA staff would allow official samples to be collected for further investigation, but is entirely voluntary for the growers involved,” he said, adding that his research team is currently wrapping up the sampling phase of the project, with data analysis continuing into 2023.

While commending the “huge coordinated effort” by the California citrus industry, California Department of Food and Agriculture, UC ANR and other partners to suppress the ACP vector and slow the spread of HLB, McRoberts also urged continued vigilance.

“Our study results indicate that it is not time to declare the emergency status for ACP/HLB in California over – the situation is still evolving,” he said.

California Ag Today2022-11-21T11:20:37-08:00November 21st, 2022|

Western Growers Premieres Video Series Featuring Next-Generation Agtech Robots

By Ann Donahue, Western Growers

From two-dimensional orchards to flying autonomous robots to lasers killing weeds, today’s agriculture combines the best of science and science fiction.

To celebrate the start of the first American edition of FIRA, the international agricultural robotics conference, WG debuts an inside look at cutting-edge technologies on the farm that will help ease the industry’s ongoing labor shortage.

The three short videos feature 2-D orchards of trees harvested via a self-propelled platform; flying autonomous robots working alongside harvest crews; and AI-directed blades and lasers that zap weeds with ruthless efficiency.

The videos are available in their entirety now on the Western Growers YouTube channel, and will be rolled out on WG social platforms. Click here for a playlist of all the videos; links for individual videos and their embed codes are available below.

Future of Tree Fruit Harvesting

Drone Harvest

Robotic Weeding

California Ag Today2022-10-18T09:41:17-07:00October 18th, 2022|

Confirmation of New Citrus Virus in California

By Citrus Insider

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) has confirmed positive identifications of Citrus yellow vein clearing virus (CYVCV) in the city of Tulare detected during California Department of Food and Agriculture’s (CDFA) routine multi-pest survey. This is the first detection of CYVCV in the United States. CDFA is surveying for the disease in Tulare County residential and commercial properties and will survey in Fresno and Kings counties in the coming months to fully determine the extent of the disease’s presence (which is currently limited to the city of Tulare). The survey results will inform the regulatory approach taken by CDFA and APHIS.

CDFA began initial delimitation survey work in March in a 1-mile core radius area around the initial find site. Since then, CDFA has conducted additional surveys in the surrounding areas, which have resulted in additional CYVCV confirmations in the city of Tulare, expanding the survey area. CDFA is conducting these surveys to gain knowledge on the extent of the infestation and potential impacts of CYVCV, and surveys will be ongoing for the near future. Since the detection of this virus is new to the United States, these learnings – CDFA’s robust pest prevention system that focuses on exclusion and monitoring, as well as CDFA and USDA’s experience responding to other vectored disease threats – will be critical in developing an appropriate regulatory response.

CYVCV can be spread by vectors as they move from tree to tree feeding on foliage. The vectors include citrus whitefly, green citrus aphid, melon or cotton aphid, and cowpea aphid, which are all known to be present in California. CYVCV can also be spread through grafting and the movement of infected propagative materials and rootstocks, or contaminated tools and equipment. While there is no treatment for CYVCV, as of now the best mitigation measure is to control the vector and sanitize tools and equipment. To the greatest extent possible, growers are encouraged to urge their field crews to clean and sanitize all their equipment thoroughly in between jobs or when moving between groves.

For any questions about CYVCV, please call the CDFA Pest Hotline at 1-800-491-1899 or contact your local Grower Liaison.

California Ag Today2022-08-05T08:35:57-07:00August 5th, 2022|

DPR Announces Second Year of Enhanced Funding for Grant Opportunities to Accelerate Transition to Safer, More Sustainable Pest Management Practices

By Department of Pesticide Regulation

The California Department of Pesticide Regulation (DPR) announced $4.65 million in upcoming grant opportunities to increase the speed and the scale at which safer, more sustainable pest management practices are adopted across the state. The enhanced funds for the 2023 DPR Grants Programs cycle were allocated by the state budget and represent an increase of more than five times the amount in available funding opportunities compared to historical funding levels. Grant applications will open Monday, July 11, 2022.

“Our Grant Programs and their increased funding levels continue to play a key role in the state’s mission to advance the development and implementation of systemwide, sustainable pest management,” said DPR Director Julie Henderson. “Ongoing research, education and outreach are critical to protecting public health and preserving our environment as we accelerate the transition to safer pest management practices.”

DPR offers two grant programs focused on Integrated Pest Management (IPM) research, outreach, and implementation.

The Research Grants Program: $3.15 million to fund research into sustainable pest management practices in agricultural, urban, or wildland settings that reduce pesticide use or provide alternative methods or practices that could replace pesticides that present a risk to public health and the environment. Examples of past Research Grant projects include evaluating drone-based releases of biocontrol organisms and testing non-chemical entrapment surfaces for monitoring and control of bedbugs.
The Alliance Grants Program: $1.5 million to fund projects that promote or increase the implementation, expansion and adoption of effective, proven and affordable IPM systems or practices in agricultural, urban or wildland settings. Examples of past Alliance Grant projects include providing land managers with the best available information regarding invasive plant management through the use of an online decision support tool, as well as driving the adoption of mating disruption among small almond, pistachio and walnut growers within field clusters.

Last year’s DPR Grants Programs cycle represented the first year of increased funding allocated by the state budget. The department awarded $3.75 million in Research Grants to fund 10 research projects that explore IPM tools for urban, non-agricultural and agricultural pest management. DPR expects to award an additional $1.8 million in Alliance Grants funding later this month.

In addition to enhanced funding, DPR’s 2023 Grants Programs application process has been updated and will now offer an extended solicitation period and a streamlined application process.

The 2023 Research Grants Program solicitation period will open Monday, July 11, 2022. Applications will be accepted through Thursday, September 22, 2022.

Once the solicitation period has opened, application information, links to virtual information sessions and application materials will be available on the department’s Research Grants Program webpage.

The 2023 Alliance Grants Program solicitation period will open Monday, July 11, 2022. Applications will be accepted through Thursday, December 8, 2022.

Once the solicitation period has opened, application information, links to virtual information sessions, and application materials will be available on the department’s Alliance Grants Program webpage.

For questions or clarification concerning the DPR Grants Program, please contact DPRpmGrants.Solicitation@cdpr.ca.gov.

California Ag Today2022-07-07T15:08:59-07:00July 7th, 2022|

UC Davis Doctoral Student Alison Coomer Wins Global Nematode Thesis Competition

UC Davis doctoral student Alison Coomer is an international champion

By Kathy Keatley Garvey, UC Davis Department of Entomology and Nematology

UC Davis second-year doctoral student Alison Coomer is now a global champion.

Coomer, a member of the laboratory of nematologist Shahid Siddique of the UC Davis Department of Entomology and Nematology, just won a world-wide competition sponsored by the International Federation of Nematology Societies (IFNS) for her three-minute thesis on root-knot nematodes.

She delivered her video presentation virtually on “Trade-Offs Between Virulence and Breaking Resistance in Root-Knot Nematodes.” She will be awarded a busary and plaque at the 7th International Congress of Nematology (ICN), set May 1-6 in Antibes, France.

Coomer earlier was selected one of the nine finalists in the 22-participant competition, vying against eight other graduate students from the University of Idaho, Moscow; and universities in England, Australia, Brazil, Ireland, Kenya, Belgium and South Africa.

“Our entire lab is glad for Alison winning this award,” said Siddique. “This is an outstanding performance and Alison has really been working hard for that. I feel proud about it. I am also looking forward to Alison’s presentation at ICN.”

Judges announced that Rhys Copeland of Murdoch University, Australia, won second, and Laura Sheehy of Liverpool John Moores University England, scored third. They also will receive busaries and plaques at the 7th International Congress of Nematology.

IFNS hosts the competition, IFNS 3-Minute Thesis, “to cultivate student academic and research communication skills, and to enhance overall awareness of nematodes and the science of nematology.”

The competition began with 22 participants. Each was required to present a single static slide, and not use any props or sound-effects. In the finals, a panel of judges–six nematologists and three non-experts from other areas of plant sciend science–scored them on the quality of their research presentation, ability to communicate research to non-specialists, and the 3MT slide. (See the winning videos at https://bit.ly/3naarTe)

In her presentation, Coomer related that: “Root-knot nematodes, specifically the MIG-group, consisting of Meloidogyne incognita, javanica, and arenaria, are the most damaging of the plant parasitic nematodes causing severe yield loss in over 2,000 different plant species including tomatoes. The Mi-gene, which is a resistance gene in tomato, has been used in commercial farming and has been praised for its effectiveness towards the MIG group. This gene has been cloned but the mechanisms of how it’s resistance works is still unknown.” (See video at https://www.ifns.org/alison-coomer)

Coomer, a doctoral student in plant pathology with an emphasis on nematology and advised by Siddique, is working on her dissertation, “Plant Parasitic Nematode Effectors and Their Role in the Plant Defense Immune System.”

Coomer, originally from the St. Louis, Mo., area, received two bachelor degrees–one in biology and the other in chemistry–in May 2020 from Concordia University, Seward, Neb., where she won the Outstanding Graduate Student in Biology Award. She served as a biology lab assistant and taught courses in general biology and microbiology.

As a biological science aide/intern, Coomer did undergraduate research in the Sorghum Unit of USDA’s Agricultural Research Service. Lincoln, Neb. Her work included collecting, prepping and analyzing DNA, RNA and proteins to identify genes that contribute to an under- and over-expression of lignin in sorghum plants.

California Ag Today2022-01-11T13:12:33-08:00January 11th, 2022|

UC Davis Entomology Major Known Internationally as ‘Gwentomologist’

UC Davis entomology major Gwen Edosh with a whip scorpion she collected in Tucson. The 21-year-old undergraduate researcher has 21,999 followers on her Instagram account.

By Kathy Keatley Garvey

If you follow “Gwentomologist” on Instagram, you’ll see fascinating images, videos and data on scores of insects, including bees, butterflies and beetles, and such curious critters as wasp-mimicking beetles (genus Clytus) and “burying beetles” or Nicrophorus beetles (genus Nicrophorus).

And you’ll see arthropods such as jumping spiders (family Salticidae) and scorpions (superfamily Scorpionoidea).
Who is Gwentomologist?

She’s 21-year-old Gwendolyn “Gwen” Erdosh, a UC Davis entomology major and undergraduate researcher with 21,900 followers on Instagram, where she shares her fascination, passion and growing scientific knowledge of entomology with the intensity of a moth heading for light.

Erdosh, president of the UC Davis Entomology Club, a scholar in the campuswide Research Scholars Program in Insect Biology (RSPIB), the recipient of a Provost’s Undergraduate Fellowship (PUF) research award, and a volunteer at the Bohart Museum of Entomology, brims with enthusiasm.

In a recent post, she related how she “raised this gorgeous female Hemileuca eglanterina (sheep moth) from a tiny caterpillar!! First time successfully rearing these species. I got a male and female, and I was hoping they’d mate but it never happened. Guess they didn’t like each other. I have some eggs overwintering, and I hope they make it ‘til the spring!”

“I’m in awe with this species of silkmoth,” Gwen continued. “They are one of the few northern California native silkmoths (Saturniidae) and feed on Ceanothus and choke cherry leaves. The adults are day-flying and can fly incredible fast in a zig-zag motion, making catching them extremely hard. The males can be seen flying high in the Sierra mountains in July. Females are much harder to spot, as they are slower and hide out in the foliage, emitting pheromones to attract the males towards them.

“The best way to see the adult is to rear caterpillars,” Gwen noted. “In the past, I attempted to rear the caterpillars and ran out of host plant. With no method of transportation to the high sierras, I had to give them rose leaves, which worked…until it didn’t. They all got a disease and died. This time, I had tons of host plant, and was able to return to the mountains in my car to get more (they eat way more than you’d expect). I’m really happy that I was able to raise this species successfully, and hope to do it again next spring! The insect season is coming to a close, but certain species only come out around this time, so I’ll be on the lookout.”

Gwen launched her Instagram account in 2013 to share her passion for moths and butterflies (Lepidoptera). “Back then, it was one of only a few accounts that focused on such a niche interest,” she said. “It quickly grew in popularity and a community of insect-obsessed teenager formed, all with similar goals. Through social media, we were able to make amazing connections, which I still have today. Eventually, my passion expanded from just Lepidoptera to a fascination with every type of arthropod on the planet!”

“On my page, I mainly post my own macro-photographs with detailed captions about the featured insect,” Gwen explained. “My goal is to not only teach others, but also learn a lot myself. I also post fun and engaging videos to encourage others to pursue entomology. Many times, people have told me that my page helped them decide that they wanted to pursue entomology as a career! I love being able to spread the love of insects to others, and will continue to be active on my page.” Additionally, she maintains a YouTube account as “gwentomologist.”

A 2018 graduate of Los Gatos High School, Santa Clara County, and a UC Davis student since 2019, she anticipates receiving her bachelor’s degree in 2023. In February 2020, she applied for—and was accepted—into the highly competitive RSPIB program, which aims to provide undergraduates with closely mentored research experiences in biology. She studies with community ecologist and professor Louie Yang, UC Davis Department of Entomology and Nematology, one of the three RSPIB founders.

“I actually first met Gwen when she was still in high school,” said Professor Yang. “She was doing a research project with monarch butterflies and emailed me with a few questions. Even then, I was impressed with her knowledge, focus and determination, and was glad to hear when she came to UC Davis. She applied to the Research Scholars Program in Insect Biology early on, and was a stand-out student in my ENT 105 Insect Ecology class in 2020. It has been great to have Gwen in our lab, and to see her continuing to develop as a scientist.”

Gwen’s interest in entomology began with caterpillars.

“Ever since I can remember, I have always loved caterpillars,” Gwen said. “As a little kid, I would collect any caterpillar I saw and raise it to adulthood.” Amazed that a caterpillar could “magically change” into a moth or butterfly, she decided “to make a book matching every caterpillar to its adult. I did my own research online and in books I had, and soon was quite knowledgeable about Lepidoptera. The summer before 9th grade, I attended Bio Boot camp, the summer camp for kids led by the Bohart Museum, and Tabatha Yang (education and outreach coordinator). “This was the experience that led me to choose entomology as a career. During this camp, I learned everything about entomology and had a chance to meet real entomologists at UC Davis, and do field work. I fell in love with it and kept coming back each summer for the camp.”

Gwen started her own insect collection, inspired by Jeff Smith (curator of the Bohart Museum’s Lepidoptera collection). “Since then, I have never doubted my decision to be an entomologist, not even once. My passion only grew once I entered college, and I consider entomology a lifelong journey of discovering everything about these beautiful, intricate, and fascinating creatures.”

“Gwen is one of those students who instantly shows you her enthusiasm and enjoyment of entomology,” Smith said, “and it is just this kind of person who we hope will continue in this important field of science. For those of us looking ahead at the oncoming ‘golden years’ we need to ensure that there will be competent young scientists who will continue the research and who will discover so many more fascinating things about the world of ‘bugs.’ Gwen clearly will be one of these, and I am proud to be associated with her.”

Gwen said she is most interested in four insect orders: Hymenoptera, Neuroptera, Coleoptera and Hemiptera. “I also really like Mygalomorphs. I am really fascinated by parasitoids, and hope to do research with parasitoids (wasps, flies, etc.) in the future.”

Following her UC Davis graduation, she plans “to work abroad for a year in South America doing research. I then want to apply for graduate school in the United States. I may decide to get my masters first in systematics, and then decide if I want to get my PhD in insect ecology or insect systematics. I cannot decide between the two. However, I definitely want to pursue a career as a professor and researcher.”

Some of her role models include Louie Yang, Lynn Kimsey (director of the Bohart Museum and a UC Davis distinguished professor), Greg Kareofelas (Bohart associate), Jason Bond (UC Davis spider specialist, professor and associate dean), and Jason Dombroskie (manager of the Cornell University Insect Collection and coordinator of the Insect Diagnostic Lab.)

“It is always great to see someone be able to pursue their passion and be successful,” Kareofelas said, adding that Gwen sometimes accompanies him on his many field trips and “she is always welcome. Her enthusiasm, knowledge and energy make these trips a memorable and learning event for both of us! Her photographic skills enable her to record the insects ‘in nature’ and as a curated specimen. Her curated specimens are an example of how a collection should be made and how it should look.”

As a 15-year-old high school student, Gwen traveled to the Bohart Museum in 2016 for its annual Moth Night and conferred with many of the scientists.

At age 16, she served an entomology internship at Cornell University, where her work included identifying microlepidoptra in the family Tortricidae; sampling monarch butterflies for Ophryocystis elektroscirrha (OE) spores; catching and tagging the gray petaltail dragonfly (Petalurid) at a local state park; and collecting, identifying and presenting moths for a Moth Night program at the Roger Tory Peterson Institute of Natural History.

“It was incredible!” Gwen said. “That was my first exposure to insect systematics and I fell in love with it. We also did a lot of ecology projects in the field. The best part about it was that for the first time, I was taken seriously and treated like any other scientist–even though I was only 16. I was able to get out of my comfort zone, and grow from it. It was my first time living away from my family for an extended period of time, and it was my first experience in a professional environment. I learned how to dissect tiny moth genitalia, how to differentiate species, how new species are given names and how the process works, how to do public outreach events, how to conduct field research, and how to stay accountable. Jason Dombroskie was an amazing mentor and I seriously cannot thank him enough for his kindness, support, and encouragement.”

That was not her first internship. Gwen gained experience at a five-week internship in the summer of 2018 at the Monteverde Butterfly Gardens in Costa Rica, where she studied insects, conducted tours, and cared for the arthropods in the insectarium.

At age 12, while attending Bio Boot Camp, Gwen learned about the UC Davis Entomology Club, advised by forensic entomologist Robert Kimsey of the UC Davis Department of Entomology and Nematology. “It had always been my dream to be president one day. From the moment I entered UC Davis, I immersed myself in the club, and became extremely active in it.” She attends all the meetings and field trips; the members now include some of her closest friends. Before advancing to president this year, she served as vice president in 2020 and social media coordinator in 2019.

“I’m super passionate about the club,” Gwen acknowledged. “In fact, it’s my favorite time of the week during the quarter. The people in the club are absolutely incredible, and we all inspire each other in so many different ways. I feel so grateful that this organization exists at UC Davis, and I’m glad I have a team of officers that really put in the work to make it an inclusive, fun, and educational environment for anyone who wants to join.”

In addition, Gwen is vice president of the UC Davis STEM Careers Club, booking speakers, and inspiring students to enter the fields of science, technology, engineering and mathematics. She has also worked as a youth steward for Grassroots Ecology of Central California (removing invasive plants, planting native grasses and trees, and surveying mammals and birds using a motion-activated camera); and as a volunteer counselor at the Walden West Summer Camp, a nature summer camp for elementary-school age youths.

Although sometimes mistaken for a teenager–“I look young for my age and I’m 5′ 1”–Gwen doesn’t let that stop her. “I now have accepted who I am and I do not let what others think of me affect me or my goals. I am glad that I am unique!”

Gwen’s hobbies and interests closely align with her career plans. They include collecting, photographing, and pinning insects; exploring and observing wildlife; traveling; creating art; producing music on FL Studio (digital audio workstation); and spending time with her friends—two-legged friends (people), six-legged friends (insects) and eight-legged friends (arachnids).

California Ag Today2021-12-22T14:42:03-08:00December 22nd, 2021|

Big Research Funds Continue to Fight Huanglongbing Disease

$7 Million Multi-State Research Project Targets Citrus Threat HLB

UC ANR part of team led by Texas A&M AgriLife combating Huanglongbing disease

By Mike Hsu UCANR Senior Public Information Representative

Citrus greening, or huanglongbing disease (HLB), is the most devastating disease for orange and grapefruit trees in the U.S. Prevention and treatment methods have proven elusive, and a definitive cure does not exist.

Since HLB was detected in Florida in 2005, Florida’s citrus production has fallen by 80%. Although there have been no HLB positive trees detected in commercial groves in California, more than 2,700 HLB positive trees have been detected on residential properties in the greater Los Angeles region.

“It is likely only a matter of time when the disease will spread to commercial fields, so our strategy in California is to try to eradicate the insect vector of the disease, Asian citrus psyllid,” said Greg Douhan, University of California Cooperative Extension citrus advisor for Tulare, Fresno and Madera counties.

Now, a public-private collaborative effort across Texas, California, Florida and Indiana will draw on prior successes in research and innovation to advance new, environmentally friendly and commercially viable control strategies for huanglongbing.

Led by scientists from Texas A&M AgriLife Research, the team includes three UC Agriculture and Natural Resources experts: Douhan; Sonia Rios, UCCE subtropical horticulture advisor for Riverside and San Diego counties; and Ben Faber, UCCE advisor for Ventura, Santa Barbara and San Luis Obispo counties.

$7 million USDA project

The $7 million, four-year AgriLife Research project is part of an $11 million suite of grants from the U.S. Department of Agriculture National Institute of Food and Agriculture, NIFA, to combat HLB. The coordinated agricultural project is also a NIFA Center of Excellence.

“Through multistate, interdisciplinary collaborations among universities, regulatory affairs consultants, state and federal agencies, and the citrus industry, we will pursue advanced testing and commercialization of promising therapies and extend outcomes to stakeholders,” said lead investigator Kranthi Mandadi, an AgriLife Research scientist at Weslaco and associate professor in the Department of Plant Pathology and Microbiology at the Texas A&M College of Agriculture and Life Sciences.

The UC ANR members of this collaboration will be responsible for sharing findings from the research with local citrus growers across Southern California, the desert region, the coastal region and the San Joaquin Valley.

“In addition to the ground-breaking research that will be taking place, this project will also help us continue to generate awareness and outreach and share the advancements taking place in the research that is currently being done to help protect California’s citrus industry,” said Rios, the project’s lead principal investigator in California.

Citrus trees in Florida suffer from HLB infection

Other institutions on the team include Texas A&M University-Kingsville Citrus Center, University of Florida, Southern Gardens Citrus, Purdue University and USDA Agricultural Research Service.

“This collaboration is an inspiring example of how research, industry, extension and outreach can create solutions that benefit everyone,” said Patrick J. Stover, vice chancellor of Texas A&M AgriLife, dean of the Texas A&M College of Agriculture and Life Sciences and director of Texas A&M AgriLife Research.

HLB solutions must overcome known challenges

An effective HLB treatment must avoid numerous pitfalls, Mandadi explained.

One major problem is getting a treatment to the infected inner parts of the tree. The disease-causing bacteria only infect a network of cells called the phloem, which distributes nutrients throughout a tree. Starved of nutrients, infected trees bear low-quality fruits and have shortened lifespans.

Treatments must reach the phloem to kill the bacteria. So, spraying treatments on leaves has little chance of success because citrus leaves’ waxy coating usually prevents the treatments from penetrating.

Second, while the bacteria thrive in phloem, they do not grow in a petri dish. Until recently, scientists wishing to test treatments could only do so in living trees, in a slow and laborious process.

Third, orange and grapefruit trees are quite susceptible to the disease-causing bacteria and do not build immunity on their own. Strict quarantines are in place. Treatments must be tested in groves that are already infected.

Two types of potential HLB therapies will be tested using novel technologies

The teams will be working to advance two main types of treatment, employing technologies they’ve developed in the past to overcome the problems mentioned above.

First, a few years ago, Mandadi and his colleagues discovered a way to propagate the HLB-causing bacteria in the lab. This method involves growing the bacteria in tiny, root-like structures developed from infected trees. The team will use this so-called “hairy roots” method to screen treatments much faster than would be possible in citrus trees.

In these hairy roots, the team will test short chains of amino acids – peptides – that make spinach naturally resistant to HLB. After initial testing, the most promising spinach peptides will undergo testing in field trees. To get these peptides to the phloem of a tree, their gene sequences will be engineered into a special, benign citrus tristeza virus vector developed at the University of Florida. The citrus tristeza virus naturally resides in the phloem and can deliver the peptides where they can be effective.

“Even though a particular peptide may have efficacy in the lab, we won’t know if it will be expressed in sufficient levels in a tree and for enough time to kill the bacteria,” Mandadi said. “Viruses are smart, and sometimes they throw the peptide out. Field trials are crucial.”

The second type of treatment to undergo testing is synthetic or naturally occurring small molecules that may kill HLB-causing bacteria. Again, Mandadi’s team will screen the molecules in hairy roots. A multistate team will further test the efficacy of the most promising molecules by injecting them into trunks of infected trees in the field.

A feasible HLB treatment is effective and profitable

Another hurdle to overcome is ensuring that growers and consumers accept the products the team develops.

“We have to convince producers that the use of therapies is profitable and consumers that the fruit from treated trees would be safe to eat,” Mandadi said.

Therefore, a multistate economics and marketing team will conduct studies to determine the extent of economic benefits to citrus growers. In addition, a multistate extension and outreach team will use diverse outlets to disseminate project information to stakeholders. This team will also survey growers to gauge how likely they are to try the treatments.

“The research team will be informed by those surveys,” Mandadi said. “We will also engage a project advisory board of representatives from academia, universities, state and federal agencies, industry, and growers. While we are doing the science, the advisory board will provide guidance on both the technical and practical aspects of the project.”

Project team members:

—Kranthi Mandadi, Texas A&M AgriLife Research.

—Mike Irey, Southern Gardens Citrus, Florida.

—Choaa El-Mohtar, University of Florida Institute of Food and Agricultural Sciences, Citrus Research and Education Center.

—Ray Yokomi, USDA-Agricultural Research Service, Parlier, California.

—Ute Albrecht, University of Florida IFAS Southwest Florida Research and Education Center.

—Veronica Ancona, Texas A&M University-Kingsville Citrus Center.

—Freddy Ibanez-Carrasco, Texas A&M AgriLife Research, Department of Entomology, Weslaco.

—Sonia Irigoyen, AgriLife Research, Texas A&M AgriLife Research and Extension Center at Weslaco.

—Ariel Singerman, University of Florida IFAS Citrus Research and Education Center.

—Jinha Jung, Purdue University, Indiana.

—Juan Enciso, Texas A&M AgriLife Research, Department of Biological and Agricultural Engineering, Weslaco.

—Samuel Zapata, Texas A&M AgriLife Extension, Department of Agricultural Economics, Weslaco.

—Olufemi Alabi, Texas A&M AgriLife Extension, Department of Plant Pathology and Microbiology, Weslaco.

—Sonia Rios, University of California Cooperative Extension, Riverside and San Diego counties.

—Ben Faber, University of California Cooperative Extension, Ventura, Santa Barbara and San Luis Obispo counties.

—Greg Douhan, University of California Cooperative Extension, Tulare, Fresno and Madera counties.

California Ag Today2021-12-06T13:51:10-08:00December 6th, 2021|

Study: New Fumigation Stategy

New Fumigation Techniques for Soilborne Diseases

By Tim Hammerich with the Ag Information Network

Protecting fruit from soilborne pathogens is a big concern for strawberry growers. Researchers at the University of California Ag and Natural Resources are looking to see if a drip application of fungicides might be effective, noted UC Cooperative Extension advisor in entomology and biologicals, Surendra Dara.

“This particular study was based on a request from FMC. They wanted to evaluate if drip application of some fungicides could be supplemental to whatever the growers are currently following to control soilborne diseases. And they also wanted to see if it has any impact on improving the crop health, and potentially other diseases,” said Dara.

Dara noted the results from the first trial were positive, but he didn’t see enough incidence of soilborne disease in the control group to be sure. He’s optimistic though, given drip application of fungicides has been effective on other plant pathogens.

“They do apply fungicides to drip, but not necessarily for soilborne diseases. The management practices are usually obtaining clean transplants and fumigating or crop rotation. These are the typical management recommendations for soil-borne diseases,” explained Dara.

Dara hopes to continue to study the potential for this management practice.

California Ag Today2021-07-23T21:22:40-07:00July 22nd, 2021|

Promising Research on the Battle Against Huanglongbing in Citrus

From Marcy Martin, President of Citrus Board

We would like to share with you the status of promising preliminary research that possibly could have important ramifications for California citrus growers. Dr. Hailing Jin, a geneticist at the University of California, Riverside (UCR), has conducted greenhouse trials on young citrus plants to investigate the role of citrus-derived peptides in the battle against the deadly disease huanglongbing (HLB).

Some of Dr. Jin’s research in this area was funded in 2018-19 as Citrus Research Board (CRB) project #5200-195, Develop effective therapies to cure HLB using a novel class of citrus-derived antimicrobial peptides. The study was conducted within the University of California, Davis Contained Research Facility on year-old Madam Vinous, Washington Navel and Lisbon lemon plants that were treated through either foliar sprays or pneumatic injections.

The initial $100,000 investment by you, the growers, then served as a launching pad for a nearly $4 million grant from the U.S. Department of Agriculture-National Institute of Food and Agriculture (USDA-NIFA) to continue study on the project now titled Develop therapies using a novel class of citrus-derived dual-functional antimicrobial peptides to cure HLB trees and to protect healthy trees from infection. USDA-NIFA funding for this phase went into effect in February of last year and is scheduled to continue through January 2023.

While the long-term effectiveness of this research has not yet been confirmed or published in a scientific journal and the project is still in its early stages, Dr. Jin’s promising findings have resulted in a commercial licensing agreement between UCR and Invaio Sciences. It is not uncommon for researchers to team with commercial licensing partners during the early phases of their studies. In this case, more work still needs to be done to confirm the robustness and viability of this treatment. Additional greenhouse trials are being initiated by Dr. Jin and her team at the citrus-specific Bio-Safety Level-3 Laboratory in Riverside, California. It also is expected that field trials will be conducted to show the effectiveness of the treatment under commercial grove conditions.

Earlier this week, UCR issued a news release entitled UCR Discovers First Effective Treatment for Citrus-destroying Disease, which shares the news of a licensing agreement being reached with Invaio Sciences. While the release was understandably enthusiastic about potentially promising research and we are heartened by the commercial interest in this peptide, we are looking forward to reviewing complete studies on the effectiveness of this therapy in greenhouse and field studies.

Importantly, this is not the time to let down our guard. It continues to be critical for all citrus growers in the state to remain extremely vigilant in protecting their groves against the Asian citrus psyllid and HLB. The psyllid arrived from Mexico in 2008 and is now firmly established in southern California. The first HLB-positive tree was found in residential Los Angeles County in 2012. As of July 3, 2020, 1,926 HLB-affected trees have been identified and removed to slow the spread of the disease in residential areas of Los Angeles, Orange, Riverside and San Bernardino counties. Unlike Florida, where HLB has decimated commercial citrus groves, California growers invested in research early through the CRB and have been diligent in applying best-management practices; therefore, the disease has not yet been detected in any commercial groves. The CRB will continue to focus intensive efforts on a variety of promising research to find a solution to HLB.

Moving forward, we at the CRB are proud to work on behalf of the 3,300-plus California citrus growers to invest in key studies to find a solution to HLB. Citrus growers always have been resilient and resourceful. Together, we will look toward the horizon for a solution to HLB.

In the meantime, we continue to monitor and review progress in potential therapies, new HLB-resistant varieties, better psyllid control strategies and more. We are enthusiastic about the commercial interest in HLB therapies and look forward to being able to share a range of potential approaches for California citrus growers as research progresses and matures. If you have any questions or would like additional information about the status of this research, please contact CRB President Marcy Martin at 559.708.3791 or marcy@citrusresearch.org.