An Asian citrus psyllid (ACP) sample – confirmed positive for Candidatus Liberibacter asiaticus (CLas) the bacteria that causes Huanglongbing (HLB) – was collected from a commercial citrus grove in the Woodcrest area of Riverside County. Confirmed by Citrus Research Board’s Jerry Dimitman Laboratory, this single adult psyllid is the first CLas-positive ACP found in a commercial citrus grove in California.
While a positive ACP detection in a commercial grove is cause for serious concern, as of today, HLB has not been detected in any California commercial groves. That said, it is more crucial than ever that we stop the disease from spreading by eradicating the Asian citrus psyllid in commercial groves. The cost to manage the Asian citrus psyllid is far less than any potential costs or loss to the industry should HLB take hold throughout our state.
An expansion of the HLB quarantine zone will not be established as a result of the CLas-positive ACP detection and CDFA staff is swiftly conducting surveys and collecting samples per the ACP/HLB Action Plan from the perimeter of all commercial groves and all residential HLB host plants that are located within a 250-meter radius around the find.
While treatment is not mandatory as a result of the detection, all growers within 250-meters of the find site will be notified to apply insecticides to all HLB host material within the designated area with materials recommended by the University of California (UC).
Currently, the best way to stop the disease from spreading is to stop the ACP. To stop the ACP, we must restrict its movement and suppress existing psyllid populations. It is critical to follow best practices and review recommendations from the UC on how to protect commercial citrus groves from HLB. Regulations are in place to help prevent the spread of the pest and disease. All growers, packers and haulers must comply with all California Department of Food and Agriculture, county and federal regulations, including quarantines.
Growers in Riverside County may contact the County Agricultural Commissioner’s office or the CDFA Pest Hotline at 800-491-1899 for additional information. If you see or suspect ACP or HLB symptoms in your grove, please notify the CDFA hotline. – By the Citrus Pest & Disease Prevention Program
On March 4, 2020, China announced market access for fresh U.S. nectarines as part of the U.S.-China Economic and Trade Agreement (ETA). This report briefly mentions the market access conditions for U.S. nectarines, discusses several key factors of China’s nectarine market (including import competition), and offers market-entry recommendations to consider when exporting fresh U.S. nectarines to China.
Product Description & Access Overview
On March 4, 2020, in accordance with the U.S.-China Economic and Trade Agreement (ETA), China granted official market access for U.S. fresh nectarines from designated counties in California (specifically Fresno, Tulare, Kern, Kings and Madera counties). California nectarines account for 95 percent of U.S. production. The harvest season for U.S. nectarines runs from mid-summer to mid-autumn, partially overlapping with Chinese domestic supply, which runs from May to October. Read the full report from the USDA Foreign Agricultural Service HERE
California prune growers forced economically to make a 23% reduction in crop deliveries have also suffered a 28% reduction in price. This hardship comes in spite of a number of positive factors for the industry including $50 million in USDA purchases of prunes and positive results from trade mitigation offsets and industry promotion efforts in Japan and elsewhere. Growers reviewed the daunting double hit to grower returns from a number of factors including the disruption to trade caused by the coronavirus pandemic at the 52nd annual membership meeting of the Prune Bargaining Association (PBA) held on Thursday last week by conference call/video conference.
Average grower returns for a number of growers will fall by more than $500 per ton from the previous crop year according to data presented by PBA General Manager Greg Thompson. “Growers are to be commended for the tremendous efforts they have made to match production with demand,” explained Thompson. “Growers were told they would be paid little or nothing for smaller prunes, so they increased their efforts to prune, thin, and then screen out fruit at harvest, bringing the crop down from an estimated 110,000 tons to 85,000 tons.” As background, according to the University of California, growers have an investment of nearly $18,000 per acre (not including land) to establish a prune orchard. Growers spend an additional $4,194 per acre each year to produce and deliver the crop. “The extra effort made this past year by growers increases expenses and reduces yields,” explains Thompson. “It is truly a double whammy to have grower prices fall so precipitously.”
The brutal cut to grower prices comes in the face of many positives for the industry. Imports of cheaper but poorer quality prunes are down 76% for the first 5 months of year, while domestic shipments of California prunes are up 13%. USDA programs in response to unfair and retaliatory tariffs and trade barriers, and needy family feeding programs, have helped offset losses in overseas markets and gain back market share. Shipments to Japan, a key market for California prunes, are up 14% over the previous year. Over the past 3 years, the USDA has purchased nearly $50 million of prunes for needy families, school lunch, and other feeding programs.
One of the biggest positives for the California prune growers comes from a united industry working together to promote health and wellness through nutrition research. “Everbody wants to make a health claim these days,” explains Ranvir Singh, PBA President. “But prunes are the tried and true healthy and completely natural food. There is so much more to the health benefits of eating prunes than anyone first imagined.” Scientific research is revealing more and more about the importance of gut health to overall health. Prunes have been shown to have a positive impact on both gut health and bone health, among other bonuses. “The benefits of micro-nutrients, boron, potassium, fiber and an apparent anti- inflammation benefit in gut make prunes a truly remarkable food,” remarks Singh.
The Prune Bargaining Association was formed in 1968 as a grower-owned cooperative to improve the economy of the California prune industry, encourage the production of a quality product and provide a forum for growers to exchange ideas regarding the industry. The PBA establishes the industry’s raw product price for prunes.
Following a tip generated by citizen scientists in the Porterville/Tulare area, UC ANR researchers have installed traps to determine the potential for Velvet longhorned beetle, Trichoferus campestris (Coleoptera: Cerambycidae), introduction to the southern San Joaquin Valley. The beetle, also called Mulberry longhorn beetle, is native to Asia and Russia, but now has an extended geographic range across Europe and North America. The pest is currently established in 4 counties in Utah, with cherries and peaches serving as hosts.
The Velvet longhorned beetle is not a serious pest in Asia and has only had a low impact on European timber and orchard production. The insect pest is of concern due to its potential to impact fruit yield and decrease tree longevity. It has been repeatedly intercepted at ports of entry in California; however, it is not known to be established in the state. Because the pest has a wide host range, affecting over 40 genera of broadleaf and coniferous plants, and is tolerant of dry conditions, researchers and regulators have initiated monitoring efforts for the pest. Locally, traps have been installed in dried plum and fresh prune orchards in Tulare County.
The Velvet longhorned beetle may serve as a pest of forests and orchards, and it has been moved internationally on wood packing material and in furniture and home décor. The adult beetle is large (around 1-2 cm), brown, has long antennae, and is nocturnal. Its peak mating activity is in June/July in Utah. Black Intercept Panel Traps were established in Tulare County in June and will be removed prior to prune harvest in September. — By Elizabeth Fichtner & Houston Wilson, UC Cooperative Extension
To address nitrate pollution of groundwater, the Central Valley Regional Water Quality Control Board has initiated a regulatory program requiring growers to utilize nitrogen management practices that mitigate nitrate loading. Because nitrogen plays such a critical role in in the growth and development of avocado trees — and because it can be difficult to ensure trees are receiving the optimal amount of nitrogen — the University of California Department of Agriculture and Natural Resources has created the Nitrogen Management in Citrus and Avocado publication.
This document is designed to optimize growers’ application of nitrogen while reducing nitrogen leaching by focusing on applying nitrogen at the right rate, at the right time with the right placement and from the right source (otherwise known as the four R’s of nutrient management). The guide provides specific examples for the rate of application based on the age, alternate bearing status and vegetative state of the tree and discusses the optimal spring/fall application periods. In addition, the document provides guidance on how to conduct leaf analysis and what optimal concentration percentages to look for.
Erosion damage caused by the 2018 – 2020 California wildfires can result in discharges of sediment, metals, nutrients and other pollutants that threaten streams, aquatic life and public health. In an effort to mitigate the effects of erosion caused by the fires in Ventura and Los Angeles Counties, the Post Fire Recovery Project will allocate $320,000 worth of reimbursable supplies to applicants for their erosion control best management practices. The grants can be used to obtain items such as silt fencing, jute netting, sandbags, native plantings, seeding, straw wattles and more.
Grant funds will be distributed on a first-come, first-served basis. Interested growers can complete the application online.
Online application assistance workshops will be held August 5 at 5:30 p.m. and December 8 at 5:30 p.m. For more information, contact Andy Spyrka, Resource Conservation Specialist at andyspyrka.vcrcd@gmail.com or 805.764.5135.
UC Riverside scientists have found the first substance capable of controlling Citrus Greening Disease, which has devastated citrus farms in Florida and also threatens California.
The new treatment effectively kills the bacterium causing the disease with a naturally occurring molecule found in wild citrus relatives. This molecule, an antimicrobial peptide, offers numerous advantages over the antibiotics currently used to treat the disease.
Orange afflicted with Citrus Greening Disease. (UCR)
UCR geneticist Hailing Jin, who discovered the cure after a five-year search, explained that unlike antibiotic sprays, the peptide is stable even when used outdoors in high heat, easy to manufacture, and safe for humans.
“This peptide is found in the fruit of greening-tolerant Australian finger limes, which has been consumed for hundreds of years,” Jin said. “It is much safer to use this natural plant product on agricultural crops than other synthetic chemicals.”
Currently, some growers in Florida are spraying antibiotics and pesticides in an attempt to save trees from the CLas bacterium that causes citrus greening, also known as Huanglongbing or HLB.
“Most antibiotics are temperature sensitive, so their effects are largely reduced when applied in the hot weather,” Jin said. “By contrast, this peptide is stable even when used in 130-degree heat.”
Jin found the peptide by examining plants such as the Australian finger lime known to possess natural tolerance for the bacteria that causes Citrus Greening Disease, and she isolated the genes that contribute to this innate immunity. One of these genes produces the peptide, which she then tested over the course of two years. Improvement was soon visible.
“You can see the bacteria drastically reduced, and the leaves appear healthy again only a few months after treatment,” Jin said.
Because the peptide only needs to be reapplied a few times per year, it is highly cost effective for growers. This peptide can also be developed into a vaccine-like solution to protect young healthy plants from infection, as it is able to induce the plant’s innate immunity to the bacteria.
Jin’s peptide can be applied by injection or foliage spray, and it moves systemically through plants and remains stable, which makes the effect of the treatment stronger.
The treatment will be further enhanced with proprietary injection technology made by Invaio Sciences. UC Riverside has entered into an exclusive, worldwide license agreement with Invaio, ensuring this new treatment goes exactly where it’s needed in plants.
“Invaio is enthusiastic to partner with UC Riverside and advance this innovative technology for combating the disease known as Citrus Greening or Huanglongbing,” said Invaio Chief Science Officer Gerardo Ramos. “The prospect of addressing this previously incurable and devastating crop disease, helping agricultural communities and improving the environmental impact of production is exciting and rewarding,” he said. “This is crop protection in harmony with nature.”
Hailing Jin, Geneticist, UC Riverside
The need for an HLB cure is a global problem, but hits especially close to home as California produces 80 percent of all the fresh citrus in the United States, said Brian Suh, director of technology commercialization in UCR’s Office of Technology Partnerships, which helps bring university technology to market for the benefit of society through licenses, partnerships, and startup companies.
“This license to Invaio opens up the opportunity for a product to get to market faster,” Suh said. “Cutting edge research from UCR, like the peptide identified by Dr. Jin, has a tremendous amount of commercial potential and can transform the trajectory of real-world problems with these innovative solutions.”
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. — By Jules Bernstein, UC Riverside
Regarding the announcement, Marcy Martin from the California Citrus Research Board shared, “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.
Marcy Martin, President, California Citrus Research Board
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.”
Through the years I have had many collaborators and numerous technical staff studying a wide variety of pests including California red scale, citricola scale, cottony cushion scale citrus cutworm, katydids, earwigs, Fuller rose beetle, citrus peelminer, citrus leafminer, citrus thrips, citrus red mite, snails, ants, aphids and Asian citrus psyllid as well as their natural enemies. In the early years, the main controls for these pests were organophosphate (OP) and carbamate insecticides. The initial research goal was to get these replaced with more selective insecticides that would allow natural enemies to participate in pest management. We successfully documented OP resistance in California red scale and citrus thrips and developed replacement insecticides that created a more balanced situation resulting in a reduction in pesticide use (as few as 4 treatments/year in the San Joaquin Valley). But alas, citrus IPM programs must change because new situations arise. For the citrus industry, the three drivers of change in the second half of my career have been drought exacerbating some pests, export countries demanding in- field treatments for insects as a replacement for Methyl Bromide (MeBr) fumigation, and the arrival of various invasive pests. These situations have provided me ample opportunities to work with regulators and the citrus industry and challenged my creative problem-solving abilities – never a dull moment.
It is hard to say if the past 8-9 years of higher temperatures and on and off drought conditions are a permanent ‘climate’ change or are part of a cycle. However, they have certainly made California red scale more difficult to control. Growers have shifted from treating for California red scale once every other year to treating 3-4 times per year. Extra heat units have added an extra generation of scale per year and occasionally allowed scale development in winter. My research response has been to study and provide outreach on the use of California red scale pheromone disruption as an assist to reduce insecticide treatments. I am encouraged to hear reports of some acreage going back treatments every few years for California red scale.
Export issues with S. Korea (Fuller rose beetle and California red scale) and with Australia and New Zealand (bean thrips and mites) began to crop up in the 2010s. In the past, shipments from California would be inspected at destination and, if there were any insects or mites of phytosanitary concern, the fruit would be fumigated with MeBr. With the worldwide reduction in MeBr use, there is now the expectation that California growers apply in-field treatments to eliminate these pests so fumigation at destination is not necessary. Complete disinfestation of an orchard is impossible to achieve so we launched studies on alternative fumigants and cold treatments that could be applied in California or during transport.
Invasive pests such as glassy-winged sharpshooter, Diaprepes root weevil, citrus leafminer, and Asian citrus psyllid have been arriving regularly into California since about 2000. In each case, I evaluated chemical and biological controls, evaluated the level of damage they could inflict and conducted outreach to prepare the citrus industry. Of course, Asian citrus psyllid has been the most significant invasive pests because of its ability to transmit the bacterium that causes the deadly disease huanglongbing. My role has been to develop control strategies for growers around the state and assist them with their psyllid management programs.
If I had to list the top three favorite projects of my career, they would be the following:
Working with colleagues to survey 13 crops around the state to see what species of predatory mites are found and developing a ‘Key to the Phytoseiid Predatory Mites of California Crops’ (submitted for publication with UC ANR).
Working with cottony cushion scale and predatory vedalia beetle and figuring out how to protect the vedalia from insect growth regulators by careful timing of the application of those pesticides. This is a great example of making an incompatible insecticide compatible with a sensitive natural enemy.
3. Directing five technicians to scout 224 commercial citrus orchards around the state and see how grower applied pesticide treatments affect the psyllid populations. The results of this project led to strong recommendations for eradication and areawide psyllid treatment programs.
For the past 14 years, all of this was accomplished while also acting as Director of the Lindcove Research and Extension Center. That position also had challenges with hiring and directing personnel, building facilities such as a laboratory, a greenhouse and a screenhouse structure, and attracting research and extension programs to the Center. It has been very rewarding to see the Center expand its capacity and reputation.
Finally, I couldn’t have done any of this without the amazing technical staff and collaborators that have supported my projects for many years. I will miss the challenges of this job, but I expect to dip back in when needed at Lindcove and I look forward to new life challenges as I spend more time with my family and my community.
Some may think Navel Orangeworm is just a pest of almonds and pistachios, but there are other crops it thrives off of as well. Watch this brief interview with Bob Klein from the California Pistachio Research Board as he shares his insights on preferred overwintering hosts for this pest as well as in-season comparisons. It’s going to take a unified approach across industries to defeat this pest.
Temperature highs ranged from the mid 40s to low 70s in the mountains, low 60s to low 80s along the coast, low 60s to mid 80s in the valley, and low 60s to high eighties in the desert. Temperature lows ranged from the mid 10s to high 40s in the mountains, mid 30s to mid 50s along the coast, low 30s to mid 60s in the desert, and low 40s to mid 60s in the valley.
FIELD CROPS
In Tulare County, winter grain plants were in different stages of growth, with most wheat, oats and barley coming close to maturity. Some wheat, oats, and barley fields were being treated for weed control. With the added rain, alfalfa continued to thrive and was growing well. Corn was being planted. Safflower planting was finished with most emerged. Due to cold weather, cotton planting was behind schedule. Rice ground preparation was ahead of schedule with ground work done in the Sacramento Valley.
FRUIT CROPS
Stone fruit orchards continued to near the end of bloom and immature stone fruit was steadily developing. Nectarines, peaches, and plumscontinued to size as expected. Cherry and pear fruit were sizing also, but still in the immature stages of growth. Pomegranates, persimmons, and grapes continued to leaf out, with warm weather boosting grape vine budding. Lemon and grapefruit harvest continued. Naveloranges, tangelo, and mandarin harvest progressed well. Tangerine groves continued to be covered with netting to prevent pollination by bees during the bloom period.
NUT CROPS
Almond development was ongoing, with a few areas predicting a more than favorable crop. Walnuts continued to awaken from winter dormancy. Pistachio leaf out remained steady with no reported issues.
VEGETABLE CROPS
Summer vegetable fields were prepared for planting. Processing and fresh tomatoes were showing good growth. Artichokes were harvested in San Mateo County. Onion, garlic and parsley fields were growing well in Fresno County. Tulare County reported summer vegetables developed well with warm temperatures and adequate rains. Strawberries were produced and grew well. Garlic, onions and peas did well under mulch.
LIVESTOCK
Recent precipitation and the week’s warming temperatures promoted range development. Rangeland and non-irrigated pasture were reported to be in good condition. Movement of cattle to spring pasture began. Some bee hives were moved to citrus orchards and to the foothills.
The Velvet longhorned beetle may serve as a pest of forests and orchards, and it has been moved internationally on wood packing material and in furniture and home décor. The adult beetle is large (around 1-2 cm), brown, has long antennae, and is nocturnal. Its peak mating activity is in June/July in Utah. Black Intercept Panel Traps were established in Tulare County in June and will be removed prior to prune harvest in September. — By Elizabeth Fichtner & Houston Wilson, UC Cooperative Extension
