California Fruit and Vegetable

Category: Pest/Disease Management

  • Effective Non-chemical Soil Fumigants for Organic Production

    The Organic Center — Soil fumigants that fight soil-borne diseases and ensure crop production continue to be banned to protect the health and safety of rural communities. Organic farmers and conventional farmers who can no longer use these chemical tools need effective alternatives to protect their yields. A recent study published in the journal Agronomy(link is external) demonstrates that a non-chemical alternative can be effective and affordable if farmers receive a high enough price for their crops. Until 2016, Methyl Bromide had been used in California for decades as a soil fumigant to disinfest soils of devastating diseases before planting high-value crops such as strawberries. Methyl Bromide was never permitted for use in organic farming, and its recent ban due to public health safety concerns also left conventional farmers without an important disease control tool. The ban has prompted much research into alternatives to chemical soil fumigants such as steam, solarization, and anaerobic soil disinfestation (ASD) using rice bran or mustard seed meal. While many studies are optimizing the effectiveness of these strategies, a missing key component is the consideration of the economic cost of these alternatives. This study took a comprehensive approach, and measured the effectiveness and affordability of two alternative management strategies to chemical soil disinfestation for strawberries produced under conventional and organic management.

    The results show that organic-approved methods of soil disinfestation (steam and steam plus mustard seed meal) resulted in better yields compared to the control for both conventional and organic systems. And when the cost of treatment is considered, along with yield and crop value, organic far out-competes conventional management. In this study, organic yields were greater than conventional, which helped better cover the high cost of soil treatment. The higher price premium earned for organic strawberries even further enhanced the affordability of the soil treatment for organic management. This study shows that a non-chemical method of managing devastating soil diseases is effective and affordable, but only if the farmer receives a high enough price to cover the added expense. This study brings up an important consideration: when we ask farmers to use practices that benefit not just their own production, but also their surrounding environment which improves public and environmental health of rural communities, it’s clear that the farmers need financial assistance to make the safer choice.

  • Successful HLB Management Strategy in CA Focuses on Everyone Doing Their Part

    What Nobel Prize-winning Economics Research Tells Us About ACP and HLB Management in California

    As you have likely heard many times, coordinating management measures for the Asian citrus psyllid (ACP) and Huanglongbing (HLB) over a larger scale than individual properties is key to achieving effective control and limiting the spread of the disease. Coordination is important in terms of surveying for HLB-positive trees and removing them from the ground as soon as possible, applying insecticide treatments at the same time for multiple citrus groves within a Psyllid Management Area (PMA) or a Pest Control District (PCD), complying with quarantine measures for the movement of bulk citrus, using certified budwood and sharing information with neighbors.

    But this coordination comes at a cost, and some individuals may be tempted to skip the costs of treating within the recommended window for ACP, correctly tarping their trucks, or even investing some time to convince their neighbors about the importance of these measures. Yet, if everyone skipped these costs and relied on the efforts of others, the ability of the citrus industry to combat HLB would be greatly reduced, leading to a higher risk of HLB spread in California.

    This temptation to free-ride on the efforts of others exists in the management of many natural resources, such as groundwater, fisheries or forests. In 2009, social scientist Elinor Ostrom received the Nobel Prize for Economics for studying how societies organized themselves to manage these types of resources and avoid the problem of free-riding. Throughout her career, she studied many different cases of this problem in different parts of the world, and she identified eight principles that were associated with sustained collective action. Interestingly, most of these principles are present in the strategy for HLB management in California, as shown in the table below.

    Due to a lack of participation in coordinated mitigation tactics – the free-rider problem – a similar HLB-management program in Florida was not as effective in keeping HLB at bay. But California has so far been more successful in achieving collective action than other infected areas like Florida, and as is seeing more success in preventing the spread of ACP and HLB, including keeping HLB out of commercial groves.

    To continue to stay a step ahead of HLB, it is crucial that California’s citrus industry and residents remain vigilant and engage in coordinated management efforts and follow best practices and regulatory requirements.

    Although Ostrom’s principles do not offer a universal solution to all free-riding problems, they can be useful to guide our efforts as we continue to work together to face the threat of HLB.

    More information on her research, which was recently published in Food Security Journal, can be found on https://doi.org/10.1007/s12571-020-01133-9 — By Sara Garcia Figuera, Citrus Pest & Disease Prevention Program

    Design Principle (Ostrom, 1990) HLB Management in California
    1. Clearly defined boundaries: the boundaries define who is responsible for the collective effort and over what area, reducing the cost of monitoring behavior.
    • PMAs
    • PCDs
    2A. Congruence between rules and local conditions: the rules that are established for the management and maintenance of a resource are aligned with the predominant social norms, culture and agro-ecological conditions in a community.
    • Rules defined by the citrus industry through Citrus Pest and Disease Prevention Committee (CPDPC) in collaboration with County Agricultural Commissioners (CACs) and California Department of Food and Agriculture (CDFA)
    • Some pre-existing PCDs
    • Quarantine zones and rules defined by local conditions (citrus production, ACP populations and/or climatic suitability)
    2B. Congruence between appropriation and provision rules: correspondence between the rules governing contributions to the maintenance of the resource system, and the rules governing withdrawal of resources from the system.
    • Insecticide treatments for ACP funded by individual growers.
    • Other assessments based on production volume (CPDPP) or acreage (PCD)
    3. Collective-choice arrangements: if local users who directly interact with one another can define the rules that regulate the day-to-day decisions about the use of a shared resource, they will be in a better position to incorporate local knowledge.
    • AWM organized locally through PCDs or PMAs
    • CPDPC establishes rules in collaboration with CDFA
    4A. Monitoring users: a community needs to be able to identify users that do not comply with rules; otherwise there can be no credible commitment. Monitoring should be undertaken by the resource users, better than by external authorities.
    • Seasonal reports of areas treated for ACP
    • Packinghouse inspections of grate cleaning or spray & harvest
    4B. Monitoring the resource: assesses the extent to which the collective effort is being achieved.
    • ACP monitoring by CDFA, CACs, Citrus Research Board (CRB) and pest control advisors (PCAs) hired by growers
    5. Graduated sanctions: Although sanctioning prevents an excessive violation of community rules, sanctions should be graduated based on the severity and/or repetition of violations to ensure proportionality. And they should be imposed by the resource users or officials accountable to them, to maintain community cohesion.
    • If less than 90% of the acreage is treated in a PMA or PCD, it will not qualify for the residential buffer treatment
    • When there is a violation of the tarping requirement, a notice of violation is sent before further sanctions
    6. Conflict-resolution mechanisms: Low-cost conflict resolution prevents the cost of conflict from outweighing the benefits of successful collective action.
    • Task Force meetings and other public meetings have been used for addressing conflicts
    7. Minimal recognition of rights to organize:Local institutions are more effective when higher levels of government allow users to self-organize in ways that reflect local social and ecological contexts.
    • CPDPC
    • PCDs
    • Grower leader in PMAs
    8. Nested enterprises: refers to the importance of connecting smaller social systems that manage different parts of a larger resource system to facilitate cross-scale coordination.
    • Statewide program coordinated at the regional, county and local level
    • Grower liaisons

  • Fusarium Wilt of Watermelon 2021

    Last year we had a lot of watermelon fields infected with Fusarium from Winterhaven to Yuma, Wellton, and Mohawk Valley. Rain, and overwatering of fields when plants set fruits might have contributed to the disease development.

    Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum, is one of the oldest described Fusarium wilt diseases and the most economically important disease of watermelon worldwide. It occurs on every continent except Antarctica and new races of the pathogen continue to impact production in many areas around the world. Long-term survival of the pathogen in the soil and the evolution of new races make management of Fusarium wilt difficult.

    Symptoms of Fusarium can sometimes be confused with water deficiency, even though there is plenty of water in the field. In Yuma valley we have seen fusarium problem in some overwatered fields.

    Initial symptoms often include a dull, gray green appearance of leaves that precedes a loss of turgor pressure and wilting.  Wilting is followed by a yellowing of the leaves and finally necrosis.  The wilting generally starts with the older leaves and progresses to the younger foliage. Under conditions of high inoculum density or a very susceptible host, the entire plant may wilt and die within a short time.  Affected plants that do not die are often stunted and have considerably reduced yields.  Under high inoculum pressure, seedlings may damp off as they emerge from the soil.

    Initial infection of seedlings usually occurs from chlamydospores (resting structure) that have overwintered in the soil.  Chlamydospores germinate and produce infection hyphae that penetrate the root cortex, often where the lateral roots emerge.  Infection may be enhanced by wounds or damage to the roots.  The fungus colonizes the root cortex and soon invades the xylem tissue, where it produces more mycelia and microconidia.  Consequently, the fungus becomes systemic and often can be isolated from tissue well away from the roots. The vascular damage we see in the roots is the defense mechanism of the plant to impede the movement of pathogen.

    Disease management include planting clean seeds/transplants, use of resistant cultivars, crop rotation, soil fumigation, soil solarization, grafting, biological control. An integrated approach utilizing two or more methods is required for successful disease management. — By Bindu Poudel, University of Arizona Extension

  • Summer Sanitation is Important as Ever

    It is never too early to start planning for next produce season, particularly with the threat of Impatiens Necrotic Sprot Virus (INSV) looming. As many of you know, INSV was found in several Yuma locations this spring, particularly in the Tacna area. Overall, INSV incidence was very low (~1% incidence), but there were a few fields where incidence was estimates at > 25% (see Chart 1 below).

    With desert lettuce production now finished, the question remains; will INSV in these infested areas survive the summer in the absence of lettuce. Of course, this depends on the availability of host plants in the cropping landscape to serve as reservoirs for INSV in the next 4 months, as well as the abundance of western flower thrips on these hosts. A team of applied scientists at the UA Yuma Ag Center –Bindu Poudel, Stephanie Slinski, Barry Tickes, Marco Pena and myself (with the assistance of Daniel Hasegawa, USDA-Salinas) – are currently trying to determine this.  First, we know that many of the common weeds currently found in drainages, field borders, and ditch banks serve as reproductive hosts for western flower thrips.  What this means is that thrips are capable of colonizing these weed hosts. Immigrating adults can transmit viruses and larvae can acquire viruses that can be transmitted after they emerge as adults. Recent areawide monitoring of crops and weeds in Tacna and Yuma Valley showed thrips adults and larvae were abundant on nettle leaf goosefoot and cheeseweed (see Chart 2 below), and more importantly, tissue samples recently collected from weeds near previously infected lettuce fields in Tacna tested positive for INSV in nettleleaf goosefoot, cheeseweed, and purslane.   It appears that these weeds could provide a green bridge for the virus and the vector from now till September. The threat of INSV surviving within our desert cropping system in the absence of lettuce this summer is real.

    So, weed management this summer is going to be very important if we hope to eliminate the local presence and spread of INSV.  Growers should be extremely vigilant in keeping ditch banks and low-lying drainages adjacent to fields free of weeds. When upcoming wheat harvests are completed, all weeds along field edges need to be thoroughly disked under along with the stubble.  Even a few remaining goosefoot or purslane plants on a field edge can potentially harbor INSV and a significant number of thrips vectors. Similarly, periodic disking of alfalfa borders and field edges should help minimize weed regrowth.  Same goes for cotton and Sudan grass fields. When spring melons are harvested, growers should promptly disk under plant residue.  Any PCA watching melons this spring can attest to the attractiveness of melon flowers to thrips. Finally, as growers start to flat water fields in preparation for fall lettuce planting, it will be as important as ever to promptly control weeds emerging in those fallow blocks. Remember, recent weed sampling showed purslane tested positive for INSV, and a ten-acre field infested with purslane can potentially generate a lot of thrips. So can volunteer melons.  Thus, summer sanitation is as important as ever. Bottom line:  anything growers can do to reduce weed abundance in and around their fields can only help. For more information on this crop sanitation, please visit Weed Interference with Insect Management in Desert Crops.  The other critical question we are working on is whether our summer crops (alfalfa, cotton, melons) serve as hosts and reservoirs for INSV. We do not know yet, but our team is working on it.  We’ll let you know when we know. — John Palumbo, University of Arizona Extension

  • ARS Citrus Rootstocks: A Success Story

    Remember that old commercial that declared, “A day without orange juice is like a day without sunshine”? Thanks to the Agricultural Research Service (ARS), consumers can enjoy “citrus sunshine” whenever they like. Begun by USDA more than a century ago, the citrus research program has helped to ensure a bounty of not only oranges, but also grapefruits, mandarins, lemons, and more.

    But that bounty was severely threatened in 2005 with the appearance of a new and destructive disease. Citrus greening, or huanglongbing (HLB), has caused Florida citrus production to plummet around 70 percent in the 15 years since the disease hit U.S. citrus groves. HLB, which causes low yields, yellowed leaves, and bitter-tasting fruit, is caused by a bacterium, Candidatus Liberibacter asiaticus. So far, there is no cure.

    Like other crops, citrus crops are susceptible to a variety of diseases and pests. One reliable way to fend off those threats is to graft the fruit-producing part of a tree (the scion) to the lower trunk and root system (the rootstock) of a different tree that has been bred to resist the disease or pest. Rootstocks are also used to obtain specific tree sizes, yields, and fruit quality, among other goals.

    A 6-year-old Owari Satsuma Mandarin tree on US-942 rootstock developed by ARS. In this trial, US-942 was the highest yielding rootstock, averaging more than 300 pounds of fruit per tree (Photo by Jake Price, University of Georgia).

    With ARS’s long history of helping growers keep their groves healthy and productive, the agency had the expertise required when HLB appeared. To quickly address the problem, the ARS citrus breeding project was refocused in 2005 partly to develop new, HLB-tolerant, highly productive citrus rootstocks.

    Led by Kim Bowman, a plant geneticist in the ARS Subtropical Insects and Horticulture Research Unit in Fort Pierce, FL, the team released 12 new HLB-tolerant citrus rootstocks between 2007 and 2018. Before and after the releases, Bowman conducted dozens of field trials to evaluate and validate the rootstocks’ performance, providing the scientific data needed to demonstrate their potential and gain industry acceptance. These rootstocks, all with the prefix “US,” have since become a key component in the survival of the Florida citrus industry.

    ARS plant geneticist Kim Bowman in front of 5-year-old Valencia orange trees on HLB-tolerant rootstocks he and his colleagues developed (Photo by Diane Helseth).

    Not surprisingly, demand for the rootstocks was extremely high, and growers also needed assurances that they’d be getting the real deal. Bowman arranged for the plant material to be certified disease-free by the Florida Department of Agriculture, paving the way for the rootstocks to be commercially propagated on a large scale.

    Bowman and his colleagues have also done a great deal of research on rootstock propagation. Even though most common citrus rootstocks can be grown uniformly from seeds, it takes several years for a young tree to produce a lot of seeds, and the seeds of many new rootstocks don’t grow into true-to-type plants. The scientists have shown that using plant cuttings or tissue culture is an acceptable alternative to starting new rootstock trees from seed, and it’s a much faster way to create hundreds of thousands of plants.

    The use of these alternative methods has dramatically increased propagation for some of the new rootstocks, so that nurseries are not limited by seed supply.

    From 2018 to 2020, the HLB-tolerant “US” rootstocks were used to produce nearly 3 million new citrus trees, or about 37 percent of all trees propagated in Florida. These rootstocks have also proven effective in areas affected by other diseases besides HLB. The rootstock “US-942” demonstrated the most consistent outstanding performance in field plantings and was the most popular rootstock in Florida from 2018 to 2020, with about 1.8 million trees propagated during that 2-year period, or about 22 percent of all propagations.

    For more information, visit Citrus Rootstocks.—By Sue Kendall, USDA-ARS Office of Communications.

  • Whitefly Management on Spring Melons 2021

    Now that the produce season is essentially finished in Yuma, it is time to move into melons.  Spring melon crops are rapidly growing, and so are insect pest populations. Cabbage loopers and leafminers are becoming evident in some areas, and PCAs should start ramping up their monitoring and sampling. More importantly, whitely populations are quietly becoming abundant on the spring melons of all sizes. Adults can easily be found on recently planted melons located at the Yuma Ag Center, and reports from local PCAs suggest that adult populations are beginning to show up on older plantings. As temperatures increase and crops/weeds mature, avoidance of excessive feeding from whitefly nymphs should be the primary concern on all melon types. Although CYSDV does occur in later spring melons, it is rarely yield limiting. But honeydew and sooty mold contamination on cantaloupes, mixed melons and watermelons can significantly reduce quality and marketability is whiteflies are not adequately controlled.  Our research has shown that to prevent fruit yield and quality losses on spring melons, a foliar insecticide treatment should be applied on threshold; that is, when leaves have greater than 2 adult whiteflies per leaf, when averaged across an entire melon field. At this level of adult abundance, immature populations are just starting to colonize, and timing sprays based on the adult threshold has been shown to significantly reduce the chance of yield / quality losses during spring harvests.  This threshold applies for the use of recommended IGRs (Courier, Knack, Cormoran, and Oberon), foliar applied neonicotinoids (Assail, Venom, Scorpion), neonicotinoid-like compounds (Sivanto prime and Transform), diamides, (Exirel and Minecto Pro) and the new feeding disruptors (PQZ and Sefina).  For more information on whitefly management and available insecticides, go to these documents on IPM and Whitefly Management  and  Whitefly Control Options-Spring 2021.     Also, be aware of honey bees and other pollinators in or around melon fields. If bees are present, be sure to carefully read labels and determine bee safety of a product before making an application in a melon field.  If applications are necessary during bloom, only apply a product that is considered bee safe (e.g., PQZ, Sefina, Sivanto, Assail). We also recommend that insecticides only be applied when honeybees are not actively working in the field (e.g. 10:00 pm – 3: 00 am). — John Palumbo, University of Arizona, Yuma College of Ag & Life Sciences

  • CDFA Teams up with Partners to Introduce California Pollinator Coalition

    A broad array of organizations from across California’s agricultural and environmental landscape today announced a working coalition to address their shared commitment to the health of wild and managed pollinators.

    The Coalition is focusing on increasing the value working lands provide to our environment, to benefit biodiversity and farmers alike. The California Pollinator Coalition, convened by Pollinator Partnership, the California Department of Food and Agriculture, and the Almond Board of California, includes more than twenty organizations–representing the large majority of California’s crop and range land–pledging to increase habitat for pollinators on working lands.

    Together, the goal is to increase collaboration between agriculture and conservation groups for the benefit of biodiversity and food production. The result will be on-the-ground improvements, technical guidance, funded research, documentation of relevant case studies, and tracked progress toward increasing healthier pollinator habitats.

    Achieving this bee friendly goal is laden with benefits for farmers and the environment in California, increasing biodiversity and sequestering more carbon in the soil.

    The Coalition also hopes its success will serve as a model for even more collaboration among interests who have not always been aligned, but who are willing to come together in partnership to confront common challenges.

    “What we are doing in California is acknowledging the urgency to address the critical issue of protecting all pollinators, including native and managed species,” said Laurie Davies Adams, President and CEO of Pollinator Partnership. “Agriculture and conservation must work together to achieve this goal, especially when we will be facing many of the same issues –increasing temperatures, erratic and unpredictable weather, fires, drought, soil depletion, and more. The outcome will not be a tidy report that sits on a shelf, but rather a metric of acres, projects, and species added to the landscape while agriculture continues to profitably feed the nation.”

    The collective land represented by coalition members will provide the critical mass to address habitat on an unprecedented scale, for the benefit of beneficial insects, such as bees, butterflies, beetles, wasps, moths and more. California is home to more than 1,600 native bees and hundreds of other species of pollinating insects. Globally, pollinators provide service to more than 180,000 different plant species, more than 1,200 crops, and are responsible for producing an estimated one out of every three bites of food. They sustain our ecosystems and support natural resources, all while adding $217 billion to the global economy each year.

    But pollinator populations are declining and often suffer from the same challenges as California’s agriculture. The Coalition will work together on a variety of fronts to support pollinators:

    •Preparing farmer-friendly guidance to buildand maintainpollinator habitat on farms and ranches

    •Promoting voluntary, incentive-based habitat establishment projects and Integrated Pest Management (IPM) practices

    *Conducting research and disseminating relevant science

    •Monitoring outcomes (adoption rates and effectiveness of practices)

    “Collaborative action can mitigate risks to California’s pollinators, and that’s exactly why this coalition has come together,” said Karen Ross, Secretary of California Department of Food and Agriculture. “We need urgent action, yet the first step in the process is building trust that encourages, enables, and enhances the result. The California Pollinator Coalition is a big step forward in a journey of grower and conservation groups voluntarily demonstrating leadership.”

    “This will not be an easy or quick fix,” said Josette Lewis, Chief Scientific Officer of the Almond Board of California. “It will require a robust and sustained effort, but we are determined to be part of the solution. Almond growers and many other farmers depend on pollinators to produce a crop and pollinators depend on us to provide safe habitat. Working lands can and should be part of the solution.”

    “Farm Bureau supports voluntary, farmer-friendly efforts to improve habitat for native pollinators, and we have long advocated improved research on pollinator health,” said Jamie Johansson, President of the California Farm Bureau. “We will work with the coalition for the benefit of native pollinators and managed bees, and to assure stability for the domestic bee business.”

    “Climate change will affect the wildlife of California and the way we grow food in many ways,” said Dan Kaiser, director of conservation at Environmental Defense Fund. “The best chance for biodiversity and farms to thrive is to rebuild the natural infrastructure that supports pollinators, soil health and water resilience throughout the Central Valley. This coalition will promote robust research and guidance to support a more resilient and biodiverse agricultural landscape.”

    While just beginning its work, the Coalition is catalyzing new collaborations and continuing to recruit partners who understand the urgency and share the common goal of supporting both the health of pollinators and agriculture. Current California Pollinator Coalition membership includes:

    • Agricultural Council of California
    • Almond Alliance of California
    • Almond Board of California
    • California Alfalfa and Forage Association
    • California Association of Pest Control Advisers
    • California Association of Resource Conservation Districts
    • California Cattlemen’s Association
    • California Citrus Mutual
    • California Department of Food and Agriculture
    • California Farm Bureau Federation
    • California State Beekeepers Association
    • California Sustainable Winegrowing Alliance
    • Environmental Defense Fund
    • Monarch Joint Venture
    • Monarch Watch
    • Pollinator Partnership
    • Project Apis m.
    • University of California Agriculture and Natural Resources
    • USDA Natural Resources Conservation Service of California
    • Western Growers
    • Dr. Neal Williams, University of California, Davis

    About the California Pollinator Coalition — The California Pollinator Coalition, convened by Pollinator Partnership, the California Department of Food and Agriculture and the Almond Board of California, is made up of a diverse group of agricultural and environmental organizations with the shared goal of providing enhanced habitat for pollinators. The Coalition and its members have pledged to increase habitat for pollinators on working lands. Additionally, the group plans to promote research and track its progress toward healthy and abundant habitats.

  • CDFA Teams up with Partners to Introduce California Pollinator Coalition

    A broad array of organizations from across California’s agricultural and environmental landscape today announced a working coalition to address their shared commitment to the health of wild and managed pollinators.

    The Coalition is focusing on increasing the value working lands provide to our environment, to benefit biodiversity and farmers alike. The California Pollinator Coalition, convened by Pollinator Partnership, the California Department of Food and Agriculture, and the Almond Board of California, includes more than twenty organizations–representing the large majority of California’s crop and range land–pledging to increase habitat for pollinators on working lands.

    Together, the goal is to increase collaboration between agriculture and conservation groups for the benefit of biodiversity and food production. The result will be on-the-ground improvements, technical guidance, funded research, documentation of relevant case studies, and tracked progress toward increasing healthier pollinator habitats.

    Achieving this bee friendly goal is laden with benefits for farmers and the environment in California, increasing biodiversity and sequestering more carbon in the soil.

    The Coalition also hopes its success will serve as a model for even more collaboration among interests who have not always been aligned, but who are willing to come together in partnership to confront common challenges.

    “What we are doing in California is acknowledging the urgency to address the critical issue of protecting all pollinators, including native and managed species,” said Laurie Davies Adams, President and CEO of Pollinator Partnership. “Agriculture and conservation must work together to achieve this goal, especially when we will be facing many of the same issues –increasing temperatures, erratic and unpredictable weather, fires, drought, soil depletion, and more. The outcome will not be a tidy report that sits on a shelf, but rather a metric of acres, projects, and species added to the landscape while agriculture continues to profitably feed the nation.”

    The collective land represented by coalition members will provide the critical mass to address habitat on an unprecedented scale, for the benefit of beneficial insects, such as bees, butterflies, beetles, wasps, moths and more. California is home to more than 1,600 native bees and hundreds of other species of pollinating insects. Globally, pollinators provide service to more than 180,000 different plant species, more than 1,200 crops, and are responsible for producing an estimated one out of every three bites of food. They sustain our ecosystems and support natural resources, all while adding $217 billion to the global economy each year.

    But pollinator populations are declining and often suffer from the same challenges as California’s agriculture. The Coalition will work together on a variety of fronts to support pollinators:

    •Preparing farmer-friendly guidance to buildand maintainpollinator habitat on farms and ranches

    •Promoting voluntary, incentive-based habitat establishment projects and Integrated Pest Management (IPM) practices

    *Conducting research and disseminating relevant science

    •Monitoring outcomes (adoption rates and effectiveness of practices)

    “Collaborative action can mitigate risks to California’s pollinators, and that’s exactly why this coalition has come together,” said Karen Ross, Secretary of California Department of Food and Agriculture. “We need urgent action, yet the first step in the process is building trust that encourages, enables, and enhances the result. The California Pollinator Coalition is a big step forward in a journey of grower and conservation groups voluntarily demonstrating leadership.”

    “This will not be an easy or quick fix,” said Josette Lewis, Chief Scientific Officer of the Almond Board of California. “It will require a robust and sustained effort, but we are determined to be part of the solution. Almond growers and many other farmers depend on pollinators to produce a crop and pollinators depend on us to provide safe habitat. Working lands can and should be part of the solution.”

    “Farm Bureau supports voluntary, farmer-friendly efforts to improve habitat for native pollinators, and we have long advocated improved research on pollinator health,” said Jamie Johansson, President of the California Farm Bureau. “We will work with the coalition for the benefit of native pollinators and managed bees, and to assure stability for the domestic bee business.”

    “Climate change will affect the wildlife of California and the way we grow food in many ways,” said Dan Kaiser, director of conservation at Environmental Defense Fund. “The best chance for biodiversity and farms to thrive is to rebuild the natural infrastructure that supports pollinators, soil health and water resilience throughout the Central Valley. This coalition will promote robust research and guidance to support a more resilient and biodiverse agricultural landscape.”

    While just beginning its work, the Coalition is catalyzing new collaborations and continuing to recruit partners who understand the urgency and share the common goal of supporting both the health of pollinators and agriculture. Current California Pollinator Coalition membership includes:

    • Agricultural Council of California
    • Almond Alliance of California
    • Almond Board of California
    • California Alfalfa and Forage Association
    • California Association of Pest Control Advisers
    • California Association of Resource Conservation Districts
    • California Cattlemen’s Association
    • California Citrus Mutual
    • California Department of Food and Agriculture
    • California Farm Bureau Federation
    • California State Beekeepers Association
    • California Sustainable Winegrowing Alliance
    • Environmental Defense Fund
    • Monarch Joint Venture
    • Monarch Watch
    • Pollinator Partnership
    • Project Apis m.
    • University of California Agriculture and Natural Resources
    • USDA Natural Resources Conservation Service of California
    • Western Growers
    • Dr. Neal Williams, University of California, Davis

    About the California Pollinator Coalition — The California Pollinator Coalition, convened by Pollinator Partnership, the California Department of Food and Agriculture and the Almond Board of California, is made up of a diverse group of agricultural and environmental organizations with the shared goal of providing enhanced habitat for pollinators. The Coalition and its members have pledged to increase habitat for pollinators on working lands. Additionally, the group plans to promote research and track its progress toward healthy and abundant habitats.

  • Healthy Roots, Healthy Trees: HLB & Soil Microbes

    The rhizosphere, defined as the soil environment that surrounds the plant roots, is a rich and diverse habitat for microbes. Some members of the rhizosphere microbiome (or collection of microbes), are good, others bad while many are just there and don’t provide any benefits or harm to the host. One function of the good microbes in the rhizosphere is to help facilitate the availability and assimilation of nutrients and water from the rhizosphere. Just like the human gut, the plant rhizosphere conveys key nutritional functions and the analogy was made that “plants wear their gut on the outside”. One example is the symbiotic relationship between legumes (peas, beans) and rhizobia. Those bacteria help the plant fix atmospheric nitrogen in exchange for carbon supply. Another example is the symbiotic relationship between the plant and mycorrhizal fungi, whereby the mycorrhizae receive carbon from the plant in exchange for increased nutrient uptake (principally phosphorus and nitrogen). There is undeniable evidence that plants have developed a mechanism for recruiting good microbes to cope with environmental stress such as protection against opportunistic pathogens or drought. The rise of ‘omics’ technologies have helped profile entire microbial communities associated with plants and shed light in their biological functions. This research has fueled the development of novel commercial bioproducts to address the increasing consumer’s demand of environmentally-friendly products. As a result, there has been several commercial ‘probiotics’ and ‘prebiotics’ that have been marketed for agricultural use including many biocontrol agents such as fungal- (e.g., Trichoderma) and bacterial- based (e.g., Bacillus, Streptomyces, or Pseudomonas) bioproducts.

    One goal of my research program is to identify beneficial microbes for tree and vines crops, promote practices that support the presence and abundance of beneficial microbes and figure out how good microbes help combat pathogens and support plant health. As part of a collaborative project (UC Riverside, University of Florida, USDA-ARS) funded by the California Citrus Research Board and the USDA-NIFA, we profiled the microbiome of citrus trees in the context of Huanglongbing disease (or HLB). HLB is a highly destructive and lethal disease to all commercial citrus cultivars making it a threat to citrus production globally. Finding strategies that do not only rely exclusively on management of the insect vector of the bacterium (the Asian Citrus Psyllid), is a priority to the citrus industry. In our research, we found that there were significant tissue-specific microbial shifts occurring within the citrus microbiome as trees get sicker, especially in the root compartment. As HLB progressed, there were depletions of beneficial species in roots, such as mycorrhizal fungi, and enrichments of parasitic microorganisms, such as Fusarium and Phytophthora (see Figure). HLB-affected trees decline because of the clogging the phloem sieve tubes, which limit movement of sap and translocation of sugar to the roots, hence leading to feeder root collapse. Once tree is weakened, it becomes more susceptible to pathogens such as Phytophthora which further weakens the trees and exacerbate above ground HLB symptoms. In addition, several studies from Florida suggested that cultural practices that supported root health and rhizosphere microbiome richness and diversity limited root collapse.

    Figure: Citrus decline caused by HLB (https://apsjournals.apsnet.org/doi/10.1094/PBIOMES-04-20-0027- R – Ginnan et al. 2020. Phytobiomes); canopy thinning, wood dieback, feeder roots decline, collapse of beneficial microbes and enrichment of pathogens in roots.

    Our group was recently awarded another research funding by the USDA-NIFA Emergency Citrus Disease Research and Extension program (project director, M.C. Roper, Microbiology and Plant Pathology, UC Riverside). This research effort in collaboration with UC Agricultural and Natural Resources, UC Davis, University of Florida, and the USDA-ARS aims at investigating the root collapse associated with HLB- impacted trees and finding ways to mitigate it by promoting root health. In the proposed work, we will test how different sectors of the root microbiome contribute to or lessen fibrous root loss and if soil amendments (e.g., humic acid treatment, mulching) and planting of HLB tolerant rootstocks (Poncirus trifoliata and P. trifoliata hybrids) can be used to mitigate root loss associated with HLB in Florida, and how tree respond to those practices under a HLB free environment in California. While these approaches will not cure trees from HLB, it will provide a science-based information for strategies that support root and tree health and sustain orchard longevity until remedies are discovered. — By Philippe Rolsausen, Professor in Cooperative Extension, UC Riverside

  • Tarped Against Asian Citrus Psyllid

    Researchers at the California Data Analysis and Tactical Operations Center (DATOC) have analyzed Asian citrus psyllid (ACP) trapping data along major transportation routes before and after tarping regulations for bulk citrus shipments were enacted. The purpose was to determine the effectiveness of the policy.

    DATOC is an independent group of scientists sponsored by the Citrus Research Board and the California Citrus Pest and Disease Prevention Program. The group was formed in 2016 to create and amend tactical response plans for huanglongbing (HLB) suppression and management for California citrus.

    DATOC found a significant reduction in the rate of ACP finds throughout the San Joaquin Valley (SJV) after tarping regulations went into effect. The SJV contains more than 70% of California’s packinghouses. Coastal and Southern California counties ship more than 63 million pounds of bulk citrus into the SJV annually for processing.

    Source: Citrus Pest & Disease Prevention Program

    In years past, ACP populations have soared as they presumably “hitchhiked” on trucks that weren’t properly covered, coming from Southern California into the SJV and threatening the livelihood of commercial groves throughout California along the way. However, after the California Department of Food and Agriculture (CDFA) required tarping in 2017, DATOC data shows that tarping has effectively reduced ACP movement.

    While these results are encouraging, scientists say that growers must continue to remain vigilant. In a recent letter, Citrus Pest & Disease Prevention Committee (CPDPC) chairman Jim Gorden stated that ACP populations are expected to “flare up” occasionally, such as the late 2020 ACP detections in Kern, Madera, San Luis Obispo, Santa Barbara, Santa Clara, Tulare, Contra Costa and other counties.

    The CPDPC emphasizes that growers, packers, transporters and other stakeholders must continue to stay on top of this elusive ACP pest and the dangerous HLB disease it spreads. The upfront cost to manage ACP is much less than the potential hit to the citrus industry if HLB spreads throughout the state.

    In order to move bulk citrus from an ACP regional quarantine zone or a HLB quarantine area under the terms of the permit(s), growers, grove managers, haulers and harvesters must comply with the CDFA’s transporting requirement as detailed in their order. Get specific details here. — By Ben Faber, UCCE Advisor, Ventura & Santa Barbara Counties