As growers navigate SGMA, different avenues are being explored for access to the needed water for crops, including groundwater markets. This has been experimented with in the Mojave Basin, resulting in stabilized implementationand aggregate gains, but also a consolidation of water rights. At the World Ag Expo, UC Cooperative Extension Associate Professor Ellen Bruno discussed the findings on groundwater markets with Matthew Malcolm at California Ag Network. Watch this quick video and read more in California Fruit & Vegetable Magazine.
Please thank this video’s sponsor Simplot for their industry support.
Mark Bolda, coastal UCCE Strawberry and Caneberry Farm Advisor, was easing into some Sunday morning reading recently at a small park in Watsonville that is very close to a strawberry field when the unusual insect depicted below paid him a visit. Given that he had never seen this insect (and doubts that many of you have either), he felt a surge of unease that this could be a new one, in other words an invasive.
A quick check to Dylan Beale, our new UCCE Entomologist serving all three counties of the Central Coast, put all of this to rest. After some research into the identification, Dylan determined that this very likely Megaloceroea recticornis, of the insect family Miridae. The species originated in Eurasia and North Africa but has become established in North America and New Zealand. Nymphs and adults prefer to feed on grasses, which makes a lot of sense since this is exactly the environment it was found.
All is well then, and we can continue on to other things.
As part of the UC Ag Experts Talk webinar series, Dr. Jaspreet K. Sidhu, Vegetable Crops Farm Advisor with the University of California Cooperative Extension, Kern County, will lead the next webinar on October 9, 2024 (3 – 4 p.m.). She will discuss carrot production in California’s Central Valley, the biggest producer in the U.S. Dr. Sidhu will include major pest challenges and pest management with research findings for management especially for root knot nematodes, Alternaria leaf blight and cavity spot. One DPR CE unit (other) and one CCA CE unit (IPM) are pending. In order to qualify for credit, a final exam will be given and must be passed with a 70% or higher. Register to attend this free webinar HERE.
By Sudan Gyawaly, UCCE Northern Sacramento Valley IPM Advisor — ‘Leaf curl plum aphid’ and ‘mealy plum aphid’ are the key pests of prune orchards in the northern Sacramento Valley. Both aphid species survive the winter in the orchard at egg stage near the base of buds. Once hatched, around bloom time, they vigorously feed on the young foliage and build up their population quickly. From May (leaf curl plum aphid) and June/July (mealy plum aphid), most aphids leave the prune trees and feed on alternate weed hosts outside the orchard.
Mealy plum aphid
Both aphid species infest growing leaves and stems in spring and summer, which can cause curling and stunting of the leaves. Serious aphid infestation can reduce tree growth, vigor, and potentially reduce fruit sugar content. Accumulation of honeydew, which these aphids excrete while feeding, results in the development of sooty mold which can potentially lead to fruit cracking.
Damage caused by plum leaf curl aphid, Jack Kelly Clark, UC IPM
Determining the need to spray for aphids and optimum spray timing.
The decision to spray for aphids depends on the past and present orchard aphid pressure, which also helps determine the optimum spray timing. Also, the need to spray for other prune pests (such as scale or peach twig borer) can influence the selection of materials and application timings for aphids. Several pesticide options are available for aphid control for different application timings (see table, below). An effective aphid management program should always weigh the relative cost, efficacy, and impacts on natural enemies and surface water quality.
If aphids are a consistent problem in an orchard, a late fall/early dormancy (Nov-early Dec) spray with a low label rate of a pyrethroid insecticide provides good control of aphids. Low label rates of these insecticides applied at this time are effective, yet the risk of surface water runoff is reduced. Oil spray during this period can seriously impact parasites (natural enemies) and is not recommended, especially if leaves are still on trees.
Dormant sprays (late Dec-Jan) of pyrethroid or pyrethroid plus oil treatments are effective against aphids and other pests, such as scale and PTB. However, this application timing poses higher risks of surface water contamination.
If a fall/dormant spray is not applied, dormant spur sampling can help decide the need for aphid sprays at bloom. Dormant spur sampling for aphids involves sampling for aphid eggs, and the treatment threshold for aphids is just 1 egg out of 100 spurs. However, aphid eggs can be hard to find on dormant spurs, and not finding eggs on spurs doesn’t mean none are present. Therefore, a spring/summer monitoring is necessary to complement the dormant spur sampling if no eggs were found on dormant spurs. Bloom time sprays of narrow-range oil are effective against aphids.
If aphids are only an occasional problem in the orchard and sprays were not applied at fall/dormant or bloom time, the need to spray for aphids is based on spring/summer monitoring. Spring/summer aphid monitoring involves weekly monitoring (from petal fall until a treatment is applied or July 15) of 40 trees/block for aphid infestation and determining if those trees have significant (aphid covering >10% of tree leaf surface) aphid infestations. Treatment is warranted if a threshold (12 out of 40 trees monitored in a block) have significant aphid infestation. Click this link for details on spring/summer monitoring.
The table below (adopted from Franz Niederholzer) provides a good summary of various prune aphid control materials, their application timings, efficacy against key prune pest and risks to water quality.
Label is the law. Always read the label of the product being used.
Disclaimer: Products listed in this table do not constitute a recommendation, and many of the active ingredients presented in this article can be purchased under multiple trade names.
Recently, extensive wood decay-related limb breakages have been reported in commercial prune orchards in the Sacramento Valley, adversely affecting fruit production and limiting the value of salable firewood upon orchard removal. Several fungal genera such as Phellinus, Rhodoformes, Schizophyllum, Sterum, Trametes, Ceriporia, and Perenoporia have been recognized for wood-decaying activity on California prunes. Phellinus pomaceus has been the primary organism associated with prune decay symptoms in the Sacramento Valley; however, it is yet unknown whether P. pomaceus is present in southern San Joaquin Valley prune orchards.
Figure 1: Symptoms of advanced Phellinus pomaceus infection, showing white rot internal decay of heartwood. Scale bars 10 cm.
Phellinus pomaceus, specific to prunes and other plums, is one of the commonly reported wood-decaying fungi that attack the heartwood (non-functional xylem) of mature trees (Figure 1). It tends to attack the trunk and large-diameter branches, often resulting in broken limbs and the loss of fruit-bearing scaffolds. In fact, older trees are more likely to contain infection by the fungus, and frequent pruning of large branches may increase the probability of infection due to exposure of the internal heartwood. The fungus can be identified based on its fruiting bodies that emerge as conks or shelf-like brackets that are usually hard, woody, and hoof-shaped (Figure 2). Under the right conditions, these fruiting bodies are often perennial and may exhibit a darkened upper surface after several years of development.
UCCE Tulare County assisted UC Davis researchers from the Department of Plant Pathology in surveying Tulare County prune orchards for presence of P. pomaceus. Laurel Hoffman, a PhD student working under Dave Rizzo, Professor of Plant Pathology, visited our local UCCE Tulare County office, coordinating with Elizabeth Fichtner, UCCE farm advisor, to visit and survey prune orchards for the pathogen. With the assistance of Walter Martinez, Tulare County Ag Technician, and Santosh Bhandari, Assistant Specialist, six local ‘French’ prune orchards were surveyed with data collected on tree canopy status and presence or absence of fruiting bodies associated with decay fungi. Surveyed orchards were all over 15 years old and were in varying states of overall productivity. Samples from putative decay fungi were collected and brought back to UC Davis for genetic sequencing to identify the specimens. A preliminary observation based on the initial survey suggests that the prevalence of putative decay fungi in prune orchards is lower in the southern San Joaquin Valley than in the Sacramento Valley. The presence of P. pomaceus in the southern San Joaquin Valley has not yet been confirmed.
To date, there are no control measures for management of P. pomaceus. Chemical control strategies are not available for management of this disease. Removal of fruiting bodies may limit sporulation, thus having the potential to slow disease transmission. However, the value of this technique is limited by the ability to remove conks prior to sporulation and conks may be difficult to see, particularly after leaf out. Additionally, if the pathogen is present at a high level in (or near) affected orchards, the removal of conks may not significantly influence the total load of spores at a site. Fruiting body removal would not affect the health of infected trees because they are already colonized by the fungus.
Most of California’s prunes are sold in the dried fruit market; however, a few orchards are reserved for fresh prune production. After the economic lifespan of prune orchards, trees are removed, generating wood that can either be sold as firewood, or reintroduced to the soil through whole orchard recycling. Infection with decay fungi such as P. pomaceous may adversely affect fruit production, limit the lifespan of infected trees, and reduce the economic longevity of orchards. — By Santosh Bhandari, Laurel Hoffman & Elizabeth Fichtner, UC Cooperative Extension
Save the date, Thursday February 8, 2024, for the UC Cooperative Extension 58th Annual Sweetpotato Meeting to take place at the UCCE Classroom (2145 Wardrobe Ave., Merced). Growers and industry stakeholders are invited to attend and gain research updates on sweetpotato production and marketing in California. Doors open at 7:30 a.m. where attendees can sign-in, and enjoy some coffee and Jantz Sweetpotato muffins. The meeting will run from 8AM to noon, and conclude with lunch. Following lunch, the Sweetpotato Council of California will convene their BOD Meeting. See the Annual Sweetpotato Meeting agenda below:
Efficient nitrogen fertilization management for all irrigated crops is gaining much attention as the Irrigated Lands Programs in the Central Valley and Central Coast begin efforts to minimize nitrate movement past the root zone of fruits, nuts and vegetables. The first in a series of seven educational videos on nitrogen fertilizer management is now available online. The video series is funded through a grant to CURES by the Fertilizer Research and Education Program (FREP) at the California Department of Food and Agriculture.
“The 4Rs of Nitrogen Management in Processing Tomatoes” features Zheng Wang, Vegetable Crops Advisor with the University of California Cooperative Extension (UCCE). Dr. Wang explains in the 30-minute video the current knowledge about efficient management of nitrogen in processing tomatoes by following the 4Rs: Right Rate, Time, Place and Product.
UCCE research supported by the California Tomato Research Institute shows that each ton of tomatoes requires approximately 4.6 pounds of nitrogen for efficient production. Nitrogen fertilizer injections into drip systems are best scheduled in the latter half of an irrigation set. Commercial and organic nitrogen fertilizers have varying levels of potential to move past the crop root zone. These and other agronomic and irrigation pointers are covered in the video, available in both English and Spanish. For those who want “just the facts,” 5-minute condensed versions of the video are also available.
Visit the BMP section of https://www.curesworks.org/nitrogen-management/ ; see Nitrogen Fertilizer 4R videos on canning tomatoes as well as walnuts. Coming soon in the CURES video series on the “4Rs of Nitrogen Management”: pistachios, almonds, citrus, high tonnage wine grapes, strawberries and lettuce. Sign up to be notified for all new video releases at www.curesworks.org “Contact Us.”
CURES was founded in 1997 to support educational efforts for agricultural and urban communities focusing on the proper and judicious use of pesticides and plant nutrients. Since its formation, the organization has focused its efforts on pesticide and nitrogen fertilizer stewardship and research projects, including studies on the effectiveness of management practices to minimize movement of farm inputs and sediment into surface and groundwater. A key goal is to implement educational programs, coordinate research and provide information and professional expertise to users and applicators of pesticides and nutrients to enhance and protect the environment, as well as public and worker health and safety. All its projects are implemented either by CURES staff or through partnerships with organizations such as commodity groups, water quality coalitions, private companies and the University of California.
Amber Vinchesi-Vahl, UCCE — The Pest Management Strategic Plan for Processing Tomatoes in California (see attachment) was published in May 2021 and encompasses a wealth of information on pest issues and farming practices for processing tomatoes in California.
Myself, Cooperative Extension Specialist Cassandra Swett, and UC IPM collaborated on creating this document directly from stakeholder input and funding from the Western IPM Center. Below I have highlighted the documented critical needs for managing weeds in processing tomato production in California (more detail on each can be found in the PMSP, cited below). These needs were prioritized by growers, PCAs, academics and industry for the state, the northern growing region and the southern growing region and include research, regulatory and education priorities.
“Statewide Critical Needs for Weeds
Research
Develop and identify management methods (including, but not limited to, herbicides) that work for difficult-to-control and perennial weeds, particularly nutsedge and field bindweed.
Better understand weed biology and how to influence weed biology for the purposes of weed management, especially methods to break the dormancy of belowground structures (especially field bindweed and nutsedge).
Develop effective, affordable methods to eradicate branched broomrape from processing tomato fields, prevent its spread, and manage infestations if it becomes well established in California (see Northern Region Critical Needs for Weeds for more information).
Identify effective and practical sanitation methods, especially for eliminating broomrape seed on harvesting equipment (See Statewide General Critical Needs #3).
Develop methods to detect branched broomrape and Egyptian broomrape in tomato fields more easily.” (p. 12).
“Northern Region Critical Needs for Weeds
Research
Develop integrated weed management methods (including herbicides) for difficult weeds such as fleabane, horseweed, groundcherries, velvetleaf, nightshades, and glyphosate-resistant ryegrass and sunflowers.
Conduct necessary efficacy research to register herbicides as described in the Northern Region Critical Needs for Weeds, Regulatory Needs.
Identify environmental conditions and production practices that produce different weed problems, including soil quality and water management, and the efficacy of cultural practices to manage such weeds.
Determine effective management practices for broomrape infestations.Research management practices (including herbicides) that control nightshades and reduce reliance on the costly practice of hand weeding.Research management practices (including herbicides) that control nightshades and reduce reliance on the costly practice of hand weeding.
Determine the efficacy of methyl bromide alternatives (e.g., metam sodium/metam potassium, solarization, conventional herbicides).
Identify biological control agents that may attack broomrape and test potential options.
Determine or confirm how broomrape spreads from field to field, and ways to prevent its spread.
Test efficacy of more postemergence herbicides (particularly those that can be sprayed over the top of the crop) and herbicides available for fallow bed weed control.
Regulatory
Add or expand herbicide registrations.
Register more fallow bed and preplant herbicides and increase application options (especially aerial and helicopter applications) to give growers weed control options to use in wet preplant conditions.
Explicitly register herbicides for fallow bed management, not just preplant use.
Identify and register herbicides that can be used near almond orchards.
Register herbicides for difficult weeds such as fleabane, groundcherries, horseweed, nightshades, velvetleaf, and glyphosate-resistant ryegrass and sunflowers.
Pursue 24(c) labels or Section 18 exemptions where necessary and possible.
Register postemergence herbicides that are safe to apply over the top of the tomato crop to kill late-season weeds.
Education
Educate growers and pest control advisers on how to reduce herbicide drift. Many of the herbicides registered in processing tomato (e.g., carfentrazone) have drift issues.
Conduct outreach to growers and pest control advisers about impacts of soil quality, water management, and other conditions that produce specific weed problems and how to avoid them via cultural practices.
Educate growers and pest control advisers on how to reduce and manage glyphosate-resistant weeds (especially ryegrass, fleabane, and sunflower).” (p. 17).
“Southern Region Critical Needs for Weeds
Research
Develop effective alternatives to glyphosate, especially those that are systemically translocated.
Enhance cultivation methods for removing weeds, such as via finger and torsion weeders or robotic technology.
Increase efforts to find effective biological control agents for weeds (e.g., research the effectiveness of the herbivorous mite that attacks Russian thistle).
Regulatory
Register any effective and viable alternatives to glyphosate, especially systemically translocated herbicides.
Education
Educate growers on whether or how natural enemies can be used to manage Russian thistle and other relevant weeds.” (p. 17).
Weeds come up frequently in other areas of the PMSP, especially in relation to insect pest management.
You can also find descriptions of common weed problems on page 45 and weed management practices are included in the Farming and IPM Practices section starting on page 58. There is a weed occurrence table on page 75 in Appendix I, and efficacy tables for herbicides and nonchemical management starting on page 93 in Appendix II.
Growers are excited to be gathering back in-person for the 56th annual Sweetpotato meeting held by the UC Cooperative Extension in the UCCE Classroom at 2145 Wardrobe Ave. in Merced, CA. The Sweetpotato Council of California will also be holding their business meeting right after. Due to current Covid rules, face masks will be required to be worn throughout the meeting. Attendees are invited to come and sign in at 7:30 a.m. and enjoy some coffee and Jantz Sweetpotato muffins. The meeting with end at noon with lunch. Presenters will include: UCCE Farm Advisor Scott Stoddard, Assistant Merced County Ag Commissioner Sean Runyon, Brian Hegland from Teleos Ag Solutions, Jill Silverman Hough from the Sweet Potato Council of California, Robert Drozdowski from AgriControl Technologies, and Darren Barfield from the Sweet Potato Council. DPR and CCA Continuing Education Credits have been requested. Click HERE for the full agenda.
Although you never know about the weather, we do know that if heavy rain occurs after color break in mandarins there can be significant rind breakdown. This problem can destroy much of the crop and the problem is largely preventable.
Pre-harvest rind decay of mandarins in California generally occurs shortly after rain falls and is most severe on Satsuma mandarins. Although some researchers have associated the problem with fungi such as Alternaria species, isolations from affected fruit have been inconsistent. Inoculations with isolated fungi only sometimes reproduce disease symptoms and only on water-soaked fruit. Furthermore, in preliminary field trials there were conducted in Butte Co in the fall of 2002 and 2003, fungicide treatments that included Topsin-M, Pristine and Abound only reduced the incidence of disease from 99% in the control to approximately 90% . These data suggested that mandarin rind breakdown is a physiological, abiotic disorder of fruit rather than a pathological problem and the fungi isolated are rather secondary causes of rind decay than primary pathogens.
Rind breakdown of citrus was previously reported by Fawcett and others in the 1930s. Wet weather combined with a sudden decrease in temperature was shown to result in generation of rind oil and collapse of cells just under the cuticle. In laboratory and field trials in 2003, fruit treatments with water repellants reduced the incidence of rind breakdown to very low levels. Field trials were again conducted in the fall of 2004. Fungicide treatments were ineffective in these trials. In all trials, application so Vapor-Gard or Omni oil significantly reduced the disorder. In all programs with Vapor-Gard and Omni oil, a first application was made at the end of October and there was no significant difference in efficacy when additions applications were done. When tree were protected from rainfall using a tent, the disorder could not be detected, indicating the rind breakdown is correlated to rainfall.
In summary, results from the trials support previous findings by Fawcett that mandarin rind disorder is an abiotic, weather-related problem of mature fruit that has undergone a green to orange color change. Using a water repellant helps protect the fruit. — By Ben Faber, UCCE Ventura County Advisor
As growers navigate SGMA, different avenues are being explored for access to the needed water for crops, including groundwater markets. This has been experimented with in the Mojave Basin, resulting in stabilized implementation and aggregate gains, but also a consolidation of water rights. At the World Ag Expo, UC Cooperative Extension Associate Professor Ellen Bruno discussed the findings on groundwater markets with Matthew Malcolm at California Ag Network. Watch this quick video and read more in California Fruit & Vegetable Magazine.
