- (Focus Area) Agriculture
- Author: Ben A Faber
Greening Bacterium Causes Changes in Psyllids
Recent studies, including a partnership project between Fundecitrus and the University of California, revealed that the citrus greening bacterium Candidatus Liberibacter asiaticus causes physiological changes in psyllids, posing additional challenges to management strategies. An increase in the number of eggs, more frequent dispersal flights over longer distances and greater attractiveness to the host are some of the changes observed in infected psyllids.
MORE DIFFICULT TO MANAGE
“Epidemiologically speaking, the changes we have been observing in psyllid behavior turn it into a much more problematic insect,” said Fernando Amaral, Fundecitrus agricultural engineer and post-doctoral student at the São Paulo University Luiz de Queiroz College of Agriculture.
The psyllid behavioral changes hinder the development of pheromone tools to attract the insect and improve its monitoring.
“It is becoming increasingly clear that the psyllid undergoes several changes, and this phenomenon not only poses difficulties to management, but also curbs the development of products to capture the insect,” added Fundecitrus researcher Haroldo Volpe.
Studies published between 2015 and 2024 revealed that psyllids infected with the greening bacteria can lay up to 100% more eggs than healthy insects, contributing to the growth of the psyllid population.
FREQUENT FLIERS
The studies also concluded that infected psyllids are more agitated when compared to healthy insects. In order to reach this conclusion, researchers placed adult insects from both groups on a platform. The teams noticed that infected insects flew, on average, after 50 seconds from the beginning of the observation period. The healthy subjects took around 150 seconds.
“Knowing that the insect flies more often and starts flying earlier demonstrates agitation and altered behavior, increasing its ability to spread greening,” said Volpe.
Yet another conclusion of the studies is that infected psyllids perform more frequent dispersal flights.
“Psyllids infected with the greening bacteria have a 45% higher rate of long flights when compared to healthy insects,” said Amaral.
In other words, the infected psyllid will fly longer distances and further spread the disease. Moreover, infected psyllids will also have a greater need to feed (forage) on more shoots and consequently will further disseminate the disease.
SUSCEPTIBILITY TO INSECTICIDES
On the other hand, the susceptibility of infected insects to insecticides is greater than that of healthy insects. Psyllids infected with the greening bacteria require a 20% to 313% lower concentration of insecticides to achieve the same mortality rate as healthy insects. This happens because the bacteria interferes with the psyllid metabolization of these products, which hinders their detoxication process.
CONTINUE COMBATING DISEASE
Fundecitrus General Manager Juliano Ayres emphasized the need for citrus growers to remain aware of the measures used to combat the disease in the field.
“The more diseased plants in groves without appropriate psyllid control, the more contaminated insects there will be and, consequently, the faster the disease will spread,” Ayres said. “Therefore, it is essential to continue to eliminate diseased plants from groves and keep up strict control of the insect on these plants.”
Source: Citricultor, Fundecitrus
CLas-Positive Psyllid Sample in Riverside County
July 26, 2024
An adult Asian citrus psyllid (ACP) sample from a residential property in the San Jacinto Valley area of Riverside County, California, has tested positive for Candidatus Liberibacter asiaticus (CLas), the bacterium that causes huanglongbing (HLB).
The positive sample was collected as part of the Multi-Pest Risk Survey on a residential property in Hemet. It was confirmed positive for CLas on July 17 by the Citrus Research Board's Jerry Dimitman Laboratory. Nymphs were also collected from the property and tested negative for CLas. This is the first confirmed CLas-positive adult ACP found in the San Jacinto Valley area.
An HLB quarantine zone will not be established as a result of this CLas-positive ACP detection. However, California Department of Food and Agriculture (CDFA) staff is conducting surveys and collecting samples from the property and all HLB host plants that are located within a 250-meter radius around the find, per the ACP/HLB Action Plan.
It is crucial that ACP populations continue to be controlled properly in order to stop HLB from spreading, advised California's Citrus Pest & Disease Prevention Program.
While CDFA is not requiring mandatory treatment for area commercial growers, those who wish to take proactive steps to protect their groves or who have additional questions can contact Riverside County Grower Liaison Sandra Zwaal.
In September 2023, a CLas-positive ACP sample was collected from a residential property in California's Ventura County. That sample came from a residential citrus tree in the southwest area of Santa Paula. An HLB quarantine zone was not established as a result of that detection, either. While that first confirmation of a CLas-positive ACP in Ventura County was concerning, HLB was not detected in any Ventura County citrus trees. Learn more here.
Source: Citrus Pest & Disease Prevention Program
- Author: Ben A Faber
- Author: Hamutahl Cohen
On July 30th the Queensland Fruit Fly (Qfly) quarantine was lifted in Ventura County. Qfly is part of the Tephritidae family of flies.
The Tephritidae are one of two fly families referred to as fruit flies, the other family being the Drosophilidae. Drosophila melanogaster is the fruit fly of famous biological studies to figure out how cells and genetics work. Tephritidae contain most of the flies that cause economic damage to crops because some feed on living tissue, they go after fresh fruit. To distinguish them from the Drosophilidae, the Tephritidae are sometimes called peacock flies, in reference to their elaborate and colorful markings. The Artichoke fruit fly (Terellia fuscicornis) has a limited diet, going after artichoke and presumably other thistles, so it's impact is small unless you are an artichoke grower. Spotted-Wing Drosophila (Drosophila suzukii ) which goes after soft fruits like blueberries, raspberries and strawberries can be a major economic problem, but generally Drosophilidae feed on pollen and rotting material. They are generally nuisance flies.
Some Tephritidae have negative effects, some positive. Various species of fruit flies cause damage to fruit and other plant crops. The genus Bactrocera is of worldwide notoriety for its destructive impact on agriculture. The olive fruit fly (B. oleae), for example, feeds on only one plant: the wild or commercially cultivated olive, Olea europaea. It has the capacity to ruin 100% of an olive crop by damaging the fruit. Bactrocera dorsalis is another highly invasive pest species that damages tropical fruit, vegetable, and nut crops.Euleia heraclei is a pest of celery and parsnips. The genus Anastrepha includes several important pests, notably A. grandis, A. ludens (Mexican fruit fly), A. obliqua, and A. suspensa. Other pests are Strauzia longipennis, a pest of sunflowers and a pest of blueberries. https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=60063
Another notorious agricultural pest is the Mediterranean fruit fly or Medfly, Ceratitis capitata, which is responsible for millions of dollars' worth in expenses by countries for control and eradication efforts, in addition to costs of damage to fruit crops. Similarly, the Queensland fruit fly (Bactrocera tryoni) is responsible for more than $28.5 million in damage to Australian fruit crops a year. This species lays eggs in a wide variety of unripe fruit hosts, causing them to rot prior to ripening. The Tau fruit fly (Bactrocera tau) or pumpkin fruit fly, goes after melons and other cucurbits like cucumbers and squash. The oriental fruit fly (Bactrocera dorsalis) has been seen in more than 200 kinds of fruit and nut plants.
Med, Mex, Oriental and Tau have all been in the news lately because of quarantines to contain their spread. The bulk of fruit flies, though don't pose a threat to agriculture, including all 1,500 species of Drosophilidae and the 5,000 species of Tephritidae.
Artichoke Fruit Fly - a drosophila
Tau Fruit Fly - a tephritid
- Author: Sandipa Gautam
Upcoming Citrus Extension Outreach Meetings at LREC
August 20, 2024. Register here for AAIE Organized Citrus Roundtable for SJV growers: This is an opportunity for citrus pest control advisors to get together and talk about how they manage pests. The round table will discuss Ant Control, ACP, Thrips, Red Scale, Mealybug, Weed management, current regulations and pest management problems citrus pest control advisors have had. UCANR's Dr. Sandipa Gautam, Cooperative Extension Area Citrus IPM Advisor, David Haviland, Entomology and Pest Management Farm Advisor, Jorge Antonio Angeles, Weed Management Advisor, Dr. Bodil Cass, UCR Subtropical crops Specialist, and Chris Greer Assistant Ag Commissioner, Tulare County will be presenting at this meeting.
September 24, 2024: Register here for Citricola Scale Field Day: Citricola scale has been a problem in year 2024. This 2 hour event will focus on teaching PCAs on pest identification, monitoring, and best management practices manage citricola scale.
October 2, 2024: Register here for California red scale and its natural enemies workshop. A day dedicated to California red scale and its natural enemies is back! This hands-on workshop at Lindcove will teach PCAs how to recognize the various life stages of California red scale and their parasites with dedicated time to work with each life stage. With this knowledge PCAs can determine the level of parasitism of California red scale in their citrus orchards and make better decisions about scale control tactics. Seat is limited to 30 students.
October 9, 2024: Register here for Fall Citrus Meeting at Lindcove. Are you looking for one meeting where you can learn about various issues in citrus production? UC Researchers bring to you a Fall Citrus Meeting at Lindcove Research and Extension Center on October 9, 2024. This meeting will cover nutrient management and irrigation, insect pest, disease, weed management and regulatory pest and top issues and regulations followed by a group discussion to identify grower needs pertaining to various topics.
September 11, 2024: Register here for “Workshop on the Biology and Identification of Phytoseiid Predatory Mites in Agriculture” This workshop will teach students about the importance of predatory mites in agricultural crops and the basics of how to identify them to species level. Each student will have their own phase contrast microscope and access to a set of slide-mounted specimens to work through “The Key to Genera of Phytoseiidae Found on Crop Plants in California”. Learn from the experts – Dr. Beth Grafton-Cardwell will be leading the class with David Haviland. Seat is limited to 30 students. Full Agenda attached. This workshop will be held at Kearney REC, 9240 S. Riverbend Avenue, Exeter, CA.
Attached Files CRS Annoucement October 2 2024
Local Citrus Round Table Agenda AAIE
Workshop on the Biology and Identification of Phytoseiid Predatory Mites in Agriculture
Citricola Scale Field Day Announcement - September 24 2024
Fall Citrus Meeting at Lindcove
Photo: Wax Scale, Ceroplastes ceriferus
/span>- Author: Daniel K Macon
Folks new to the world of working livestock guardian dogs (LGDs), whether they are producers or dog aficionados, often ask, “What's the best breed?” or “What breed is your dog?” I usually begin my answer with a joke: “He's a North American BWD – Big White Dog!” I then go on to explain that all of my successful dogs have usually been a mix of breeds, and that I put more emphasis on the working abilities of my dogs' parents and on desirable phenological traits (like a short coat) than I do on selecting specific breeds. My most recent dogs have all been mixes – Maremma-Anatolian, or Pyrnees-Akbash, for example. And I suspect that most working LGDs here in North America are not purebred – dogs that work in a production setting are also those who get to reproduce, regardless of whether they are purebred. Sometimes this breeding is intentional! A new paper published in iScience sheds light on the varied ancestries of modern livestock guardian dogs.
In “Multiple ancestries and shared gene flow among modern livestock guarding dogs,” the authors generated genome-wide single nucleotide polymorphism (SNP) data from 304 LGDs and combined it with public-genomic data from 2183 modern and 22 ancient dogs. Their analysis suggests shared ancestry and extensive gene flow among modern LGD breeds, which they attribute to historic livestock migrations.
The authors developed genome-wide SNP data from specific LGD breeds extended geographically from the Iberian Peninsula, through Europe, Italy, the Balkans, Western Asia, and Eastern Asia. While much of their analysis goes beyond my very simplistic understanding of genetics, their findings “strongly support the hypothesis that modern LGD breeds from East Asia and the rest of Eurasia are part of two lineages that have evolved independently for millennia.” I find this fascinating – humans who were raising livestock on rangelands in separate regions of the planet looked to dogs as protectors of their livestock! And they developed separate genetic lines with similar physical and behavioral traits!
Transhumance migration – the seasonal movement of people and livestock between high- and lowlands (following the feed) – seems to have played a significant role in the genetic flow between regionally-specificLGD breeds.Transhumance seems to have occurred across many cultures and geographic regions (and still persists today). The nomadic herders of the Mongolian steppes and the open-range sheep outfits of theIntermountain West would recognize eachother's day-to-day work.
Similar to today's Big White Dog breeding strategies, I can imagine multiple family groups taking their sheep and goats along adjacent (or overlapping) migration routes into (and back from) the high country. Perhaps my modern notions of livestock ownership doesn't exactly apply, but I suspect that each family would have tried to keep their livestock separate from the adjacent flocks. But the dogs would have mixed on the margins between these flocks! And they would have reproduced.
In his essay, “Let the Farm Judge,” Wendell Berry describes the powers of observation and adaptation employed by thousands of shepherds over thousands of years on the British Isles that allowed the development of 80 distinct sheep breeds and cross-breeds on a group of islands smaller than California. I can imagine similar observations and adaptations leading to LGD breeds in a transhumance system of livestock production. The dogs that stayed with their flocks – that protected livestock from wolves, brown bears, big cats, other dogs, and even 2-legged human predators – were noted by their owners. And allowed to reproduce – either with other dogs guarding the same flock, or with dogs guarding adjacent herds. If the offspring of these couplings didn't work, they left the gene pool.
The paper notes that reproductive management has not always been intentional in LGD breeds (nor is it today, for that matter). The authors' genetic analyses suggest that there is ongoing gene flow between LGD breeds and free-ranging dogs in specific geographic regions, stating, “Whereas breed clubs and registering bodies forbid dog owners from crossbreeding to dogs from other breeds for the purpose of maintaining traits, such restrictions are not imposed on working landrace populations and, as such, may be challenging to maintain in working dogs frequently left unattended.” In other words, dogs will be dogs – especially LGDs!
Finally, the authors discuss the relatively recent transition of some LGD breeds from working landraces to a registered system of pedigreed pets (notably the Great Pyrenees and Kuvasz breeds). In comparing pet dog genetics with those of working lines, the authors found a higher degree of inbreeding in pet dogs, likely reflective of the use of a handful of popular pedigreed sires.
These last two findings, as the authors indicate, suggest that selecting LGDs for specific guarding behaviors (attentiveness to surroundings, lack of prey drive, or submissiveness to livestock) and other factors (likelihood of roaming, or lack of aggressiveness towards people) may not be entirely (or even mostly) genetically based. In other words, reproductive isolation (that is, only breeding working LGDs to other working LGDs) may not the core mechanism for maintaining the specialized skills of LGDs. Assessing the behavior and performance of a prospective LGD during the puppy selection process becomes even more critical, given these findings – as does the bonding process. While I'm not suggesting that a well-managed bonding process will overcome poorly bred LGDs, this paper seems to confirm that genetics is just one part of a very complicated puzzle! It was a fascinating read!
Coutinho-Lima, D., et al., "Multiple ancestries and shared gene flow among modern livestock guarding dogs." iScience. 110396. August 16, 2024.
- Author: Ben A Faber
In a recent meeting the topic of where to go for irrigation information came up. Well there's no substitute for attending a class in irrigation, such as offered at Cal Poly SLO (http://www.itrc.org/classes/iseclass.htm ,
but here's some written sources to get you started thinking.
http://ciwr.ucanr.edu/california_drought_expertise/droughttips/
http://www.salinitymanagement.org/Salinity%20Management%20Guide/ei/ei_1.html
http://www.avocadosource.com/tools/IrrigationCalculator.asp
http://lawr.ucdavis.edu/cooperative-extension/irrigation/manuals
http://lawr.ucdavis.edu/cooperative-extension/irrigation/drought-tips
http://biomet.ucdavis.edu/index.php/evapotranspiration-mainmenu-32