California Fruit and Vegetable

Category: Pest/Disease Management

  • Novel Strawberry IPM Tool Included in CA DPR Grant Funding

    The California Department of Pesticide Regulation (DPR) announced $1.78 million in Alliance Grants for five projects that aim to increase the speed and the scale at which safer, more sustainable pest management practices are adopted across the state. Each project will promote innovative Integrated Pest Management (IPM) systems and practices in agricultural, urban or wildland settings.

    “Alliance Grants directly support the department’s mission to foster methods and tools to reduce reliance on pesticides and their impact on human health and the environment,” said DPR Director Julie Henderson. “We are excited by the potential of these five projects and will continue to invest in projects that promote the development and use of safer, more sustainable pest management.”

    DPR’s Alliance Grants Program funds projects that promote IPM, an approach that uses the least-toxic, effective method to solve pest problems. Since 2007, DPR has awarded more than $7.8 million in Alliance Grants. The enhanced funds for the 2022 DPR Grants Programs cycle were allocated by the 2021-22 state budget and represent a more than five-fold increase in available funding opportunities compared to historical funding levels.

    Alliance Grants are awarded to groups of experts and partners, also referred to as Alliance Teams, who work collaboratively to accomplish the goals of a given project.

    Alliance projects funded for agricultural pest management:

    • Promoting IPM practices that incorporate natural-enemy habitat to control pest insects. This project’s Alliance Team will engage in outreach with producers and agricultural professionals through videos that feature producers and researchers, field days and webinars, which will include an online continuing education course for pesticide applicators. This project will be led by Jo Ann Baumgartner at Wild Farm Alliance, a local non-profit conservation group in Watsonville.
    • Promoting the adoption of UV-C light, a non-chemical control, by strawberry growers on California strawberry farms. This project’s Alliance Team will showcase UV-C light as an effective, non-chemical alternative to chemical pesticides for controlling mites, mildew and mold. This project will be led by Dr. John Lin at California Polytechnic State University, San Luis Obispo.

    Alliance projects funded for urban pest management:

    • Addressing management of Argentine ants, the most common nuisance ant for which pesticide treatments are applied in urban environments. The Alliance Team for this project is focused on the implementation and promotion of a low-impact IPM approach for pest management professionals that uses pheromone attractants during initial treatment visits and targeted chemical baiting for maintenance visits, to reduce reliance on repeated use of insecticide sprays. This project will be led by Dr. Dong-Hwan Choe at University of California, Riverside.
    • Home visits to provide IPM education and intervention to disadvantaged communities in South Los Angeles. To improve the health and well-being of South Los Angeles residents, this project’s Alliance Team will make home visits to each family that enrolls in the program. The team will assess housing conditions; provide IPM interventions, including caulking cracks and sealing large holes; and offer other IPM education on reducing pest infestations. This project will be led by Nancy Ibrahim at Esperanza Community Housing.

    Alliance projects funded for wildlands pest management:

    • Combining manual removal of invasive primrose with native plant restoration through a private property owner incentive program, and an AmeriCorps partnership that will provide education and outreach to the community. The Alliance Team for this project is focused on management of creeping water primrose, an invasive aquatic plant, that is usually controlled with chemical pesticides. This project’s combination of IPM methods will improve water quality, protect fish habitat and enhance flood protection and prevention, as well as create strong and sustainable natural vegetative wetland communities around the shores of Clear Lake, California. This project will be led by Angela De Palma-Dow at the Lake County Watershed Protection District.For details about past recipients of DPR’s Grants Programs, please visit our department’s Pest Management Grants webpage.ABOUT THE DEPARTMENT OF PESTICIDE REGULATION

      The California Department of Pesticide Regulation protects human health and the environment by fostering safer and sustainable pest management practices and operating a robust regulatory system to evaluate and register pesticides and monitor and regulate their sale and use across the state.

      DPR’s work includes conducting scientific evaluations of pesticides to assess and mitigate potential harm to human health and the environment prior to and following registration registering all pesticides prior to sale or use in California, monitoring for pesticides in the air and water, and enforcing pesticide laws and regulations in coordination with 55 County Agricultural Commissioners and their combined 400 field inspectors across the state’s 58 counties. DPR invests in innovative research, outreach, and education to encourage the development and adoption of integrated pest management tools and practices and conducts outreach to ensure pesticide workers, farmworkers and local communities have access to pesticide safety information.

  • Citrus Research Board Secures Immense Support from Citrus Growers

    California citrus growers voted to continue their support of the Citrus Research Board (CRB) by a broad margin in a state-mandated referendum.

    The just-concluded referendum, which must be held every five years, was conducted by the California Department of Food and Agriculture (CDFA). A majority of eligible citrus producers cast their vote and their support was nearly unanimous – 97.80 percent, representing 99.51 percent of the state’s citrus volume, voted in favor of continuing the CRB.

    CDFA Marketing Branch Chief Joe Monson said, “Since the referendum results exceed the criteria required for continuation stated above, the Department has authorized the Program to continue operating for another five-year period, through September 30, 2027.”

    Over the past five years, the CRB has worked continuously to advance findings within our four research priorities: vectored diseases, pest management, production and post-harvest technology, and new varieties. Much of the research has focused on the deadly disease huanglongbing (HLB) and advancements have been made to keep the infections from spreading in California. The disease has devastated other citrus growing regions, including Florida, but the diligence of California’s growers has kept HLB from entering any of the state’s commercial groves.

    “We are pleased to once again receive the support of the industry,” said CRB President Marcy L. Martin, “and we look forward to continually improving upon the scientific pillars that allow the California citrus industry to thrive.”

    The CRB administers the California Citrus Research Program, the grower-funded and grower-directed program established in 1968 under the California Marketing Act as the mechanism enabling the State’s citrus producers to sponsor and support needed research. More information about the Citrus Research Board may be found at www.citrusresearch.org.

  • Best Farming Practices for Treated Seeds Underscores Commitment to Environmental Stewardship

    As planting season begins across the West, Western Plant Health is reminding farmers about the importance of following basic steps that will help ensure the ongoing stewardship of pesticide-treated seeds, which help reduce the overall use of pesticides.

    This major agricultural advance provides seed treatments that help protect developing seeds during their most vulnerable time – at planting and germination. Their highly targeted, precise application means less impact on the surrounding environment.

    Studies have shown that without this innovation, up to 5X’s more pesticides would have to be applied by traditional means to the crop. Fewer applications also require fewer tractor passes, which in turn reduces greenhouse gas emissions and offers yet another way for farmers to mitigate climate change.

    Treated seeds represent one of many valuable and innovative approaches enabling farmers in the West to be more productive, while using resources more efficiently and protecting the environment. That is why adopting these best practices is critical:

    1) Follow label directions on seed containers;

    2) Eliminate flowering plants and weeds in the field prior to planting;

    3) Minimize dust by using advanced seed flow lubricants and mechanisms;

    4) “Bee Aware” of honey bees and hives located near the field;

    5) Ensure that any spilled seeds are removed to protect wildlife and the environment; and

    6) Remove all treated seed left in containers and equipment after each planting, and dispose of any remaining seeds after planting is completed.

    These are simple, effective and important stewardship practices when it comes to treated seeds. Let’s help protect this critical technology for farmers by observing these practices. Remember, always follow label directions on seed containers for proper handling, storage, planting and disposal to minimize risk to applicators, wildlife and the environment!

    Farmers are the original environmentalists; properly using treated seeds is a way to continue that tradition and value to protect the land for future generations. – By Renee Pinel, President & CEO of Western Plant Health Association

  • Tips to Save Avocado from Root Rot

    Root rot is a term referring to any disease where the pathogen damage and deteriorate the plant’s root system. Root rot can occur on most woody and herbaceous plants. Root rot is caused by many soil-borne fungi. Most fungi causing root rot to prefer wet soil conditions. Some of them produce spores (microscopic biological particles that allow fungi to be reproduced) that can survive for a long time in soil or plants debris.

    Avocado root rot. Credit: California Avocado Commission

    Symptoms

    • Small, pale green, or yellow leaves
    • Wilted leaves
    • Leaves show necrotic or brown tips
    • Spare foliage and rare new growth
    • Branch dieback on top of the tree
    • A decline in fruit production
    • Small fruits

    Cause

    • Excess soil moisture or poor drainage
    • Infested soil with fungi spores

    Management

    Before infection

    • Monitor your tree regularly for disease and disease-promoting conditions
    • Purchase certified disease-free trees
    • Purchase root rot resistant cultivars
    • Inspect new tree before planting (roots and foliage)
    • Good irrigation management (stop irrigation when heavy rainfall)
    • Avoid planting your tree where you suspect there was an infected tree before
    • Plant in well-drained soil (or improve drainage by planting on a soil berm)
    • Prevent soil or water movement from an infested area
    • Apply gypsum (gypsum supplies calcium which suppresses the formation of spores
    • Use fertilizer regularly to promote good growth

    After Infection

    • Reduce irrigation schedule (especially when you forecast rainfall)
    • Add drainage around the tree
    • Dry root system by removing soil from the crown of the root system (Air drying)
    • Reapply gypsum
    • Apply fungicides such as phosphonates can help trees tolerate the disease. To apply the fungicide, follow the label. Fungicide may be sprayed onto bark or foliage, drench into the soil with irrigation water, or injected into the trunk. Remember fungicide can only help control the disease, not eradicate it.

    — By Amir Rezazadeh, University of Florida Extension

    Reference:

    UC IPM Pest Management Guidelines: Avocado
    https://www2.ipm.ucanr.edu/agriculture/avocado/Phytophthora-root-rot/

  • Asian Citrus Psyllids Found in Fresno County

    The California Department of Food and Agriculture’s Plant Pest Diagnostic Center (PPDC) has identified two Asian citrus psyllids (ACP) on a glassy-winged sharpshooter trap from a packinghouse in the Orange Cove area of Fresno County. This has been the first time that the ACP has been detected in Fresno County since November 2019.

    Following confirmation of the ACP detections, agricultural staff from the Citrus Pest and Disease Prevention Division (CPDPD) began conducting a survey and subsequently collected additional suspect ACP adults and nymphs from trees on the packinghouse premises, which were sent to the PPDC for identification.

    All residential properties with host plants within 400 meters of the detections in Fresno County will be treated to prevent ACP population spread. Any growers who are located within 800 meters of the detection site will be notified by the Fresno County Grower Liaison Teri Blaser.

    Following an increase in recent ACP detections across the Central Valley, including in Tulare and Kern counties, growers, packers, haulers and all citrus industry members are encouraged to be extra vigilant in their ACP mitigation steps and adherence to regulatory practices.

    Questions?
    Contact your regional grower liaison for the latest information on detections near you and coordinated or area-wide treatment schedules. Find your grower liaison here.

    Citrus Pest & Disease Prevention Program

  • Citrus Growers Encouraged to Increase Vigilance Following Recent ACP Detections in Central Valley

    Following recent Asian citrus psyllid (ACP) detections in the Central Valley over the last few weeks, growers, packers, haulers and all citrus industry members are encouraged to be extra vigilant in their ACP mitigation steps and adherence to regulatory practices.

    Recently, multiple ACP were detected on traps at a packinghouse in the Woodlake area of Tulare County. Upon confirmation, visual delimitation surveys began the following day. Live adults or nymphs were found and collected at two more adjacent properties, including an abandoned parcel with citrus host plants. CDFA is working closely with the packinghouse to ensure regulatory compliance. Treatment of host plants on residential properties within 400 meters of the detection will be conducted by CDFA once all necessary notifications, emergency proclamations and public meetings have been held. Commercial citrus operations within 800 meters of the detections will be asked to conduct treatments as well.

    Additionally, one ACP was recently detected on a trap at a juice plant in Visalia, and upon completion of the visual delimitation survey of the find site and adjacent properties, there were no additional finds.

    In Kern County, three ACP trap detections have been identified in the last week. One in the city, and two in rural residential locations in Southwest Bakersfield. These are the first ACP detections found in Kern County since November 2021. CDFA teams have already begun delimitation surveys and treatments will be conducted on residential properties with host plants within a 50-meter area around the detections once proper notifications, emergency proclamations and public meetings have been held. There are no commercial operations for several miles around the Kern County detections.

    These detections are a resounding reminder to continue to follow ACP mitigation best practices and regulatory requirements to efficiently suppress ACP populations and prevent the spread of Huanglongbing to the Central Valley.

     

    If you suspect ACP or Huanglongbing in your orchard, please notify the California Department of Food and Agriculture Pest Hotline at 1-800-491-1899. For questions, contact Kern County Grower Liaison Judy Zaninovich at jsleslie@msn.com, Northern Tulare County Grower Liaison Teri Blaser at tblasersci@ocsnet.net or Southern Tulare County Grower Liaison Jessica Leslie at jess.leslie@hotmail.com.

  • White Clay Spray Mix Repels Major Vegetable Pest

    Tomatoes are big business in the United States, but an insect no bigger than a grain of rice threatens growers’ fields each season.

    Kaolin and limonene applied to a seedling tomato (photo by Xavier Martini, UF/IFAS).

    The whitefly prefers the underside of leaves, enjoying a variety of plants and spreading a few diseases, including Tomato yellow leaf curl virus. The pests are also persistent, said Xavier Martini, an entomologist at the University of Florida Institute of Food & Agricultural Sciences (UF/IFAS) North Florida Research and Education Center (NFREC) in Quincy. Most commonly, growers apply insecticides weekly to the plants, which may not prevent the disease from reaching and spreading throughout a field, he said.

    “I was contacted by a local tomato producer, who has now had two recent seasons with his fields overtaken by this virus, despite weekly spraying,” Martini said. “The whitefly is able to use other plants as hosts, including surrounding row crops and weeds, which helps it to remain near crop fields even where insecticides are being used.”

    The farmer’s plight inspired Martini and Nicholas Johnston, a Ph.D. student in his lab, to look into another remedy. They assembled a team of NFREC researchers: Mathews Paret, associate professor of plant pathology; Josh Freeman, associate professor of horticultural science; and Thomson Paris, postdoctoral researcher in entomology.

    Previous studies helped narrow their testing focus to a white clay called kaolin and an essential oil called limonene, each of which is approved by the Environmental Protection Agency for agricultural use. Although previous publications have not documented use of the two in combination, kaolin’s absorbency of essential oils is well-noted.

    “These products are easily found and relatively inexpensive, and they can be applied using a tractor that is standard spray equipment on most farms,” Martini said. “They also happen to meet the requirements for organic production, so although that was not a specific goal for this study, it is a bonus.”

    The study, published in the journal Crop Protection, details applications in both closed-cage plants and open-field test plots, with some plants receiving a single type of treatment and others a combination of the two. While the single treatments resulted in fewer nymphs and adults than non-treated control plants, the combination resulted in the smallest whitefly counts.

    The next iteration of the study is testing the same combination on squash (Photo by Tyler Jones, UF/IFAS).

    “It’s not clear why the whitefly doesn’t like the leaves applied with the clay,” Martini said. “We know whiteflies are attracted to the color yellow, so we initially thought it was a visual repellent. We found that it was more likely the texture of the coating. But when combined with another type of repellent in limonene, we saw the whiteflies were even less drawn to the plant.”

    The trials required weekly applications due to plant growth and rainfall, although Martini noted the clay’s water solubility can also be viewed as a positive for producers. Any spray that may remain on harvested produce can be easily rinsed off during processing.

    UF/IFAS research on kaolin-limonene treatments is continuing, Martini said, and will next focus on squash and other cucurbits. These plants are also susceptible to whiteflies and contract diseases like cucurbit leaf crumple virus.

    The publication, “Repelling whitefly (Bemisia tabaci) using limonene-scented kaolin: A novel pest management strategy,” can be accessed at doi.org/10.1016/j.cropro.2022.105905. Research was funded through a USDA grant administered by the Florida Department of Agriculture and Consumer Services. — By Kirsten Romaguera, University of Florida Institute of Food & Agricultural Sciences

  • Growers Experience Minor Frost Damage on SO CAL Avocados

    Calls have come in – “What is the browning on the avocado leaves?  Thrips damage? Salt damage?  Dothiorella?” Nope, Frost Damage. From the end of February to the first week of March, Santa Paula had one night of 30 deg F, and 3 nights of 33 and a few nights around 35..  It wasn’t cold cold, but cold enough that there was damage to the avocados there and more so the further east and up toward Ojai.It wasn’t enough to defoliate the trees, although many were under stress from the flowering that is going on and a lot of the leaves were dropping from the flowering stress.  The damage to the leaves is a darkening of the leaf both of the bottom surfaces.  In many cases, the flower panicles got scorched. This is just the start of a big flower push and it looks like there’s a lot of flowers that have not pushed that will be fine.  It could still be a good avocado year.  The coffee really got roasted. — By Ben Faber, UC Cooperative Extension

  • Aphid ‘honeydew’ May Promote Bacteria that Kill Them

    The word ‘honeydew’ sounds benign, but the sugary waste product of aphids can promote growth of bacteria that are highly virulent to the pests, according to a new study.

    The research takes a step towards understanding how some strains of the bacteria Pseudomonas syringae that live on leaves and are pathogenic to aphids might one day be used to control the pests. Aphids transmit plant viruses when they feed on sap, costing billions of dollars in annual crop damage around the world.

    The paper, “Context Dependent Benefits of Aphids for Bacteria in the Phyllosphere,” published Jan. 12 in The American Naturalist, assessed the virulence of different strains of P. syringae to aphids. The researchers also investigated how well the bacteria survive on leaf surfaces without aphids, and whether bacteria benefited from the presence of aphids.

    “For one of the experiments, we actually took the aphids out of the picture entirely,” said Melanie Smee, the paper’s first author and a postdoctoral researcher in the lab of co-author Tory Hendry, assistant professor of microbiology in the College of Agriculture and Life Sciences.

    “We literally just sprayed fake honeydew on to leaves, and we still saw the same increase for the bacteria [as when aphids were present], so it’s really just the honeydew that’s helping the bacteria,” Smee said.

    In the study, Smee and Hendry identified 21 strains of varying virulence to aphids. They then chose eight of those strains. For each strain, they sprayed bacteria onto plants with aphids and other plants without aphids, to see if the bacteria benefited from the aphids presence. They measured bacterial growth on leaves and found that half of the strains benefited significantly.

    The next step was to try to understand the source of that benefit. They knew the bacteria are consumed and then grow within aphids and then are excreted out, so they wanted to see if passage through the aphids helped bacterial populations thrive. They set up a new experiment, with the aphids suspended above leaves that had been sprayed with bacteria. They fed one set of aphids an artificial diet with bacteria, and another set without bacteria, and the aphids then excreted honeydew onto the leaves below.

    They found it didn’t matter whether aphids were fed bacteria; all the bacteria on the leaves did better in the presence of aphids. It turned out that the honeydew was the only factor that boosted bacterial populations.

    They also found that benefits from honeydew to bacteria were not correlated to strain traits, but they were affected by the initial population densities, such that smaller populations increased more with honeydew, compared with large populations, which increased less.

    More work is needed to determine which P. syringae strains are pathogenic to plants, an important consideration if bacteria are used for pest control. The researchers are also interested in investigating the role of the interaction of bacterial communities.

    The study was funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture and by Cornell. — By Krishna Ramanujan, Cornell College of Agriculture & Life Sciences

  • Researchers Harness the Sun’s Rays to Fight Strawberry Disease

    While not exactly the stuff of sci-fi movies, scientists have developed a “ray gun” that emits a light hazardous to a pestilence that devastates many types of crops. Fumiomi Takeda, a research horticulturalist, and Wojciech Janisiewicz, retired research plant pathologist, from the Agricultural Research Service (ARS) Innovative Fruit Production, Improvement, and Protection unit in Kearneysville, WV, led a team that used shortwave ultraviolent light (UV-C) to kill powdery mildew fungus.

    UV-C is a very specific part of the ultraviolet light spectrum. UV-C is produced by the sun but does not reach Earth’s surface because it is absorbed by the ozone layer in the upper atmosphere. That’s a good thing, because UV-C is harmful to humans and plants when exposed to excessive amounts or for a long time.

    “We conducted research to administer UV-C on powdery mildew-infected strawberry plants without causing harmful effects on the plant, such as leaf burn, fruit softening, or color darkening to determine whether it would be a good alternative to controlling powdery mildew with pesticides,” Takeda said.

    On strawberry plants, powdery mildew appears as white powdery spots or fuzzy growth on both sides of leaves and on stems. Moderate to severe infection reduces the ability of leaves to employ photosynthesis – the process that plants use to synthesize foods from carbon dioxide and water. Powdery mildew can kill flowers, harden immature fruit, and reduce fruit quality and marketable yields.

    If not controlled, the disease can cause a significant economic loss, especially to plants grown in greenhouses or high tunnels. In Japan and western Europe, where over 90% of strawberry production is in the greenhouse and under high tunnels, powdery mildew is the primary cause of fruit quality loss.

    UV-C light kills microorganisms (fungi, bacteria, and viruses) and even arthropod pests by damaging their DNA.

    According to Takeda and Janisiewicz, UV-C application is most effective at night because microbes and mites have a natural, light-activated special mechanism for repairing their damaged DNA. When UV-C is used during the day, high doses are needed to kill microbes, but those high doses are damaging to plants. To avoid this problem, they irradiated microbes with UV-C at night.

    “Night-time application of 30-60 seconds allowed for control of powdery mildew, botrytis gray mold, and anthracnose fruit rot causing fungal pathogens at much lower doses for an effective kill and, more importantly, below the threshold that causes damage to the strawberry plants,” Takeda said.

    A severe case of powdery mildew on a zinnia (Photo by Stephen Ausmus).

    In addition to strawberries, USDA scientists have used UV-C light on tomato plants and ornamental crops to control fungal pathogens and arthropod pests, such as greenhouse whitefly, flower thrips, and two-spotted spider mite.

    ARS collaborated with TRIC Robotics in Newark, DE, to design and test the UV-C application robots at multiple locations, including California, where they have been field tested for over 10 months. The UV-C, non-chemical approach for fungal and pest control has shown so much success that it is on the brink of widespread commercial application.

    “With the development of our autonomous UV-C application in the field, it is not so much a question of whether UV-C light treatments can be applied effectively, but how soon commercial platforms for UV-C application will be available to large and small strawberry growers across the country,” Takeda said. – By Scott Elliott, USDA ARS