- Author: Ben Faber
The recent find of an infected adult Asian citrus psyllid in Santa Paula prompted the search for the potentially infected tree by CA Department of Food and Agriculture personnel to spread out to look and test. Two trees were found and presumably they will be destroyed. This now prompts a much more intense survey of the surrounding 2/10ths of a mile of those trees. It also places a quarantine on the movement of fruit out of that area, extending out 5 miles. That means no fruit or plant parts should be taken out of the area, potentially spreading the insects and disease to other areas, unless those plant parts have been properly treated. You can read more about the actions taken in a quarantine when infected insects or plants are found HERE . And in this document you can read about the details in and around a quarantined area and how the fruit and plants should be treated HERE.
As is the case in the spread of many invasive pests, it is humans that can be the main mode of movement of the pest and disease.
- Author: Ben Faber
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- Author: Ben Faber
Texas A&M AgriLife researchers have made a discovery that will help combat fastidious pathogens, which cost U.S. agriculture alone billions of dollars annually.
For the past few years, Kranthi Mandadi, Ph.D., a Texas A&M AgriLife Research scientist and associate professor in Texas A&M's Department of Plant Pathology and Microbiology, along with his colleagues, has been working on developing new biological technologies to fight fastidious or “unculturable” pathogens. Mandadi and members of his team are based at the Texas A&M AgriLife Research and Extension Center in Weslaco.
The results of their work, “Plant hairy roots enable high throughput identification of new antimicrobials against Candidatus Liberibacter spp.” were recently published in Nature Communications.
Fastidious plant diseases and their costs
Fastidious plant pathogens infect citrus, tomatoes, potatoes, grapes, peppers and other crops grown throughout Texas. Often transmitted by insect vectors, these disease agents cause billions of dollars of damage each year. The U.S. citrus industry alone would save $3 billion per year through control of just one of these diseases — citrus greening. Additionally, the fastidious pathogen that causes Pierce's Disease in grapes is the No.1 threat to the $1 billion wine industry in Texas.
“Currently, invasive fastidious pathogens are causing several major outbreaks in row crops, specialty crops and citrus, with immense costs to Texas and the U.S.,” said Juan Landivar, Ph.D., director of the AgriLife center at Weslaco, which has been involved in efforts to combat fastidious plant pathogens for many years.
Landivar said an expanded effort against fastidious plant diseases would protect the health of crops, environments, economies and people across the country.
A way to grow “unculturable” bacteria
Some plant pathogens can be grown as pure cultures in the laboratory in the presence of artificial nutrient solutions. Being able to culture disease agents in the lab facilitates their study by providing researchers with a reliable supply of experimental material. However, an estimated 99% of bacteria in the world are fastidious, or unable to grow outside their native environment.
“The greatest obstacle to understanding and controlling fastidious pathogens was the inability to cultivate them in a laboratory setting and to screen for lots of potential therapies,” said Leland “Sandy” Pierson, Ph.D., professor and head of Texas A&M's Department of Plant Pathology and Microbiology. “But Dr. Mandadi and his team have developed a breakthrough method as an alternative means to propagate fastidious bacteria. These bacteria are believed to be responsible for Huanglongbing, also known as citrus greening disease, and other insect-vectored diseases such as potato zebra chip and tomato vein greening disease.”
The breakthrough came in the form of the “hairy root” system. This technology utilizes the pathogen-infected host tissues to produce so-called hairy roots that can serve as biological vessels for the propagation of these pathogens in the laboratory.
“Classical microbiological techniques developed early in the 19th century cultured animal and mammalian viruses in host cells, tissues and embryonated eggs,” Mandadi said. “In a similar manner, we hypothesized that plant hairy roots could be suitable for propagating fastidious pathogens. And indeed, hairy roots supported the accumulation and growth of fastidious plant bacteria.”
Microbial hairy roots appear similar to normal root tissues that develop from the plant and mimic a bacterium's natural environment, he said. This allows the growth of the fastidious pathogens in controlled laboratory conditions.
Expedited screening for antimicrobial treatments
While microbial hairy root cultures are not traditional “pure” test tube cultures, they allow on-demand access to the fastidious bacterium in the laboratory. This enables the expedited screening of diverse antimicrobials like chemical inhibitors, immune modulators as well as gene/CRISPR-based therapies.
Other advantages are that hairy root cultures are easy to produce in the laboratory and can be maintained for several months to a year in laboratory growth chambers. Depending on the pathogen and the efficacy of screening, it is also at least four times faster than conventional screening methods, according to Sonia Irigoyen, Ph.D., and Manikandan Ramasamy, Ph.D., both AgriLife Research scientists and co-authors of the study.
In addition, the hairy root bioassays are scalable, so they can be used to pre-screen from a few to several hundred potential therapies simultaneously in a high-throughput manner. The microbial hairy root system can also be used to obtain mechanistic insights into antimicrobial function.
“Use of this technique has already led to the discovery of six new antimicrobial peptides with proven efficacy in plant materials,” Mandadi said. “These antimicrobials, either singly or in combination, could be used as near- and long-term therapies to control citrus greening, potato zebra chip and tomato vein greening diseases.”
Collaborators in the fight
“Typically, the type of breakthrough Dr. Mandadi and his team came up with is unusual for a university system off-campus center, as such centers usually have limited personnel and resources,” Landivar said. “Fortunately, the support we have received from the Texas A&M University System and other funding agencies and collaborators has helped make it possible for the Weslaco center to perform this world-class-level research.”
Besides a team of researchers at the Weslaco center, Mandadi collaborates with scientists at Texas A&M University, Texas A&M University Kingsville-Citrus Center, University of Florida, University of California System, and industry stakeholders including Citrus Research and Development Foundation, Texas Citrus Pest and Disease Management Corporation, Bayer and other entities.
Southern Gardens Citrus, a subsidiary of U.S. Sugar in Florida, has partnered with Texas A&M to commercialize the hairy root system as well as new therapies for application in the field.
Landivar also said funding from the U.S. Department of Agriculture National Institute of Food and Agriculture's Emergency Citrus Disease Research and Extension program, NIFA ECDRE, and support from the Foundation for Food and Agricultural Research and AgriLife Research's Insect-Vectored Disease Grant are making it possible to facilitate development of innovative technologies and discovery of therapies to combat diseases caused by fastidious bacteria.
To expand on his research, Mandadi recently partnered on a new project with Citrus Research and Development Foundation, Bayer, Southern Gardens Citrus, University of Florida and University of California-Davis. That project is funded by the NIFA ECDRE program. The overall goal is to bring together academics, growers and agrochemical industry to discover, develop and commercialize therapies for citrus greening disease.
Mandadi said use of the hairy root system has already been instrumental in finding several potential new treatments for citrus greening and potato zebra chip, as described in the Nature Communications article.
“We hope this technology can be further expanded to find even more therapies against current and emerging fastidious pathogens and, ultimately, with the support of industry, deploy them as field-ready products,” he said.
/h3>/h3>/h3>/h3>- Author: Ben Faber
Spanish-language Training Opportunity for Field Crews
The Citrus Pest and Disease Prevention Program is hosting three free training workshops for field crew supervisors and farm labor contractors in San Diego, Ventura and Tulare counties this month. The training workshops will be in presented in Spanish and will review best practices for field crews on how they can properly prevent the spread of Asian citrus psyllids (ACP) with a hands-on training opportunity.
The Train-the-Trainer workshops will each be a half-day in length and will take place on the following dates:
- Monday, August 21 at 10 a.m. – Escondido, San Diego County
- Tuesday, August 22 at 10 a.m. – Limoneira Co, Santa Paula, Ventura County
- Thursday, August 24 at 8 a.m. – Exeter, Tulare County
The training workshops will also fulfill the requirement listed in CDFA's harvesters/farm labor contractors' compliance agreement for these industry members to stay abreast of ACP and Huanglongbing (HLB) prevention best practices. In addition, compliance agreements will be available at the training workshops.
RSVPs are strongly encouraged. Location details, workshop start times and additional information will be sent upon RSVP. Please RSVP using the following link below.
Front-line leaders in the field will be able to learn firsthand about what they can do to reduce the risk of spreading ACP, and ultimately how to protect local groves from HLB.
During the workshop, participants will:
- Learn best practices for field crews to prevent ACP from spreading in between neighboring groves.
- Practice using effective communication techniques to help their crews and others understand these best practices and why they are important.
- Understand the threat of HLB to the livelihood of the California citrus industry.
We all must do our part if we're going to protect California citrus from this pest and disease – and field crews are at the forefront. Packinghouses are encouraged to send their staff and crews to this valuable workshop as a way to provide an extra layer of protection in preventing the spread of ACP in their groves.
For questions, please email Natalie DeAngelo at nd@nstpr.com.
Agéndela: Oportunidad de capacitación en español para equipos de campo
El Programa de Prevención contra las Plagas y las Enfermedades de los Cítricos organiza este mes tres talleres gratuitos de capacitación para los supervisores de los equipos de campo y contratistas de trabajo agrícola en los condados de San Diego, de Ventura y de Tulare. Los talleres se presentarán en español, repasarán las mejores prácticas para los equipos de campo con respecto a la prevención adecuada de la propagación del psílido asiático de los cítricos (PAC) y brindarán la oportunidad de una capacitación práctica.
Cada Taller de Capacitación para el Instructor durará medio día en las siguientes fechas:
- Lunes, 21 de agosto a las 10:00 a. m. – Escondido, condado de San Diego
- Martes, 22 de agosto – Santa Paula, condado de Ventura (luego se decidirá el horario)
- Jueves, 24 de agosto – Exeter, condado de Tulare (luego se decidirá el horario)
Se recomienda que reserve su lugar. El lugar y el horario de los talleres, así como información adicional se le enviará en cuanto reserve. Hágalo en el enlace siguiente.
Los líderes principales del campo podrán aprender de primera mano lo que pueden hacer para disminuir el riesgo de la propagación del PAC y, fundamentalmente, cómo proteger los huertos locales de la Huanglongbing (HLB).
Durante el taller, los participantes podrán:
- Aprender las mejores prácticas para los equipos de campo para prevenir que el PAC se propague entre los huertos vecinos.
- Ensayar el uso de técnicas efectivas de comunicación para ayudar a sus equipos y a otros a entender las mejores prácticas y su importancia.
- Entender la amenaza de la HLB a la subsistencia de la industria californiana de los cítricos.
Todos debemos poner de nuestra parte para proteger a los cítricos de California de esta plaga y enfermedad, y los equipos de campo están en la vanguardia. Se recomienda que las plantas empacadoras envíen a su personal y a sus equipos a este valioso taller para brindar una capa extra de protección a la prevención de la propagación del PAC en sus huertos.
Si tiene preguntas, escríbale a Natalie DeAngelo a nd@nstpr.com.
- Author: Ben Faber
Seven entities recently received $21.7 million to conduct research into combating and preventing HLB at the farm level. The funding is from the U.S. Department of Agriculture's National Institute of Food and Agriculture (USDA NIFA) Emergency Citrus Disease Research and Extension program.
The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) received the majority of the funding, more than $16 million.
PROJECTS LED BY UF/IFAS
The largest grant, at approximately $8.6 million, is for development, evaluation and delivery of citrus HLB management approaches by targeting its nature as a pathogen-triggered immune disease. The principal investigator is Nian Wang. The goal is to develop HLB management approaches for existing groves and non-transgenic HLB-resistant and HLB-tolerant citrus varieties.
Other UF/IFAS projects are:
- A coordinated network for the improvement of HLB research and Extension outputs, funded at $2 million. Megan Dewdney is the principal investigator. The project tackles the task of gathering and organizing the research findings available to growers.
- Targeted production of non-transgenic HLB-tolerant trees through complementary approaches, funded at approximately $1.5 million. Zhonglin Mou is the principal investigator. The first goal of this project is to produce non-genetically modified HLB-tolerant citrus trees by editing or silencing the promising target genes.
- HLB-resistant rootstock candidates for the citrus industry: Validating and understanding disease resistance, funded at approximately $1.2 million. The principal investigator is John Chater. This project will advance knowledge about why some rootstocks appear to be more tolerant to HLB than others.
- Providing individual protective covers and brassinosteroids to prolong health and improve fruit yield and quality in newly planted trees, funded at $800,000. Fernando Alferez is the principal investigator.
- Toward a reliable insect cell culture-based technique for culturing CLas bacteria (the causative agent of HLB), funded at approximately $793,000. Kirsten Pelz-Stelinski is the principal investigator. The project aims to have a culture system that serves as an essential research tool for increased understanding of CLas biology and for effective, rapid screening of antimicrobial agents against CLas.
- Accelerating the delivery of conventionally developed HLB-tolerant citrus scions and rootstocks as pathogen-free budlines for replicate multi-site testing, funded at approximately $536,000. The principal investigator is Jude Grosser. Successful adoption of this technology will reduce the current clean-up time by 1.5 to 2 years, and significantly increase the number of selections that can be processed.
PROJECTS LED BY OTHER INSTITUTIONS
- Virus-induced gene silencing using insect specific viruses to manipulate psyllids as a strategy to control HLB is a University of California-Davis project led by Yen-Wen Kuo.
- A method for generating an optimally attractive scent for Asian citrus psyllid biocontrol is a University of Connecticut project led by Alexander Aksenov. UF/IFAS' Lukasz Stelinski is a co-investigator.
- Endophytes as sources of antimicrobials to control HLB is being led by Kateel Shetty of Florida International University.
- Scalable low-cost organic nanocarriers for efficient foliar uptake of registered anti-HLB agents is a Purdue University project led by Kurt Ristroph.
- Citrus yellow vein-associated virus induced gene silencing vector for vaccinating seedlings and controlling HLB in infected fruit-bearing trees is a University of Maryland project led by Anne Simon.
- Molecular strategies to block psyllid transmission of the HLB pathogen is a USDA Agricultural Research Service project led by Michelle Heck.
Sources: USDA NIFA and UF/IFAS
Deformed HLB-infected fruit