Choosing when to irrigate this season with a very limited resource amidst the current drought can be quite a challenge, and the adverse effects of insufficient irrigation are already becoming manifest in the 2021 San Joaquin Valley wine grape crop. Watch this brief interview with UCCE Viticulture Advisor Karl Lund and read more about it in American Vineyard Magazine.
Please thank this video’s sponsor Vmech for their industry support.
Yesterday California state leaders enacted budget legislation to provide critical support for small and historically underserved farmers impacted by the pandemic. With approval of Senate Bill 85, state funding to the tune of $3.35 million from the California Department of Food and Agriculture (CDFA) will help ensure much-needed direct relief to farmers left out of previous aid efforts as well as language and culturally appropriate technical assistance. On behalf of our more than 8,000 farmer members, the Community Alliance with Family Farmers (CAFF) applauds the announcement, the fruit of more than a year of advocating for such crisis support.
Small farmers continue to struggle to recover from significant challenges, particularly pandemic-induced losses sustained by closed and changing markets for their fresh, local food. Previous federal and state relief efforts have failed to reach many smaller-sized farmers, particularly black, indigenous, and people of color farmers. State efforts, supported by the California CDFA, will provide not only direct relief to growers but also allow them to leverage existing and new federal sources, particularly new programs at the U.S. Department of Agriculture. This budget investment will enable CDFA to provide direct small grants to farmers in need and overlooked by other programs; will hire new University of California small farm specialists in at least two regions of the state; and contract technical assistance specialists across the state to provide support in connecting to federal resources.
“Community Alliance with Family Farmers commends Governor Gavin Newsom and the state legislature for providing on-the ground technical assistance to small-scale and socially disadvantaged farmers. CAFF pushed hard for this state support for the small and BIPOC growers in our communities that have felt some of the greatest brunt of the pandemic,” said Paul Towers, Executive Director of CAFF. “This investment will make farmers more successful. Not only is direct aid essential but so is the support from trusted and experienced partner organizations to assist farmers in navigating the myriad of state and federal COVID relief programs.”
State legislative leaders who have championed the needs of small and historically underserved farmers join CAFF in heralding this announcement:
“The investment of over $3 million in SB 85 to provide technical assistance to small and disadvantaged farmers is a big victory and welcome news,” said Senator Susan Talamantes Eggman (D-Stockton). “I’m proud to have partnered with CAFF to help build the support in the State Legislature to make this happen. These types of investments are critical as the agricultural sector works to recover from the effects of the pandemic and are central to efforts to grow and diversify our agricultural economy.”
“I am thrilled to thank the Governor, Speaker Rendon and Pro Tem Atkins for including critical technical assistance funding of $3.35 million for small farmers in this week’s round of early budget actions,” said Assemblymember Cecilia Aguiar-Curry (D-Winters). “This funding to CDFA for the UC Cooperative Extension to provide technical assistance and grants will provide desperately needed relief to our small, mid-sized, and underserved farmers to access federal disaster assistance. Federal programs are almost impossible for small players to even attempt to access–yet they’re some of the hardest hit victims of the economic and health crises of the past year. I want to send my special thanks to Secretary Karen Ross and the Community Alliance with Family Farmers for their work to secure this funding!”
“As Chair of the Assembly Agriculture Committee, I am thrilled to see the State invest in our small scale and socially disadvantaged farmers,” said Assemblymember Robert Rivas (D-Hollister). “By providing critical technical assistance funding to these farmers, this early budget action is a step in the right direction for our State and for equity in our agriculture industry.”
Community Alliance with Family Farmers is a forty-year-old organization dedicated to creating more resilient family farms, communities and ecosystems.
In Mediterranean or arid climates, particularly in areas with marginal soils, crop rotations are often limited to a narrow range of hay, pasture, a handful of winter legumes, or rainy-season grasses. Arid conditions and weathered soils drove Australia’s rainfed grain growers to adopt no-till strategies earlier than their counterparts in California. While beneficial from a water use perspective, successful no-till systems depend on herbicides to control weeds that were traditionally kept in check with tillage.
Dependence on herbicides alone in these systems has resulted in weeds with resistance to multiple modes of action. In Australia, there is one documented population of rigid ryegrass (Lolium rigidum) that is resistant to 15 different herbicides, covering seven different modes of action. Italian ryegrass (Lolium multiflorum), an annual winter species commonly found in small grain production systems in California is also notorious for its ability to develop resistance to entire groups of herbicides. One population collected in California orchards has resistance to four modes of action[1], but this population is not yet widespread.
One advantage is that California is still a long way from Australia in terms of herbicide resistance in our small grain cropping systems. We can look to Australia for 20 years of methods and data that have arisen in an effort to combat herbicide-resistant weeds. And, if we can find a way to slow the spread of herbicide resistance, we may be able to continue relying on some of the herbicides that are available in our area.
What is Harvest Weed Seed Control?
When growers need to manage herbicide-resistant populations of weeds without tillage, one strategy is to reduce the amount of seed returned to the seedbank by destroying, or removing weed seed caught during harvest operations. Collectively these strategies are referred to as Harvest Weed Seed Control (HWSC). These methods have long been studied in Australia. Researchers at Washington State University[2], Virginia, Texas, and other parts of the US have been looking into these methods for several years. With increasing herbicide resistance developing in Italian ryegrass populations in California, similar approaches may be worth exploring in the Sacramento Valley.
HWSC methods include several different strategies. Each have their own constraints and challenges, and all are designed to physically destroy seeds during or after small grain harvest. This prevents new seeds from entering the seedbank, including those that are from plants partially or fully resistant to herbicides used in the field. This reduces the rate of resistance development and the spread of resistant genes.
Narrow-windrowing – Sorting straw and chaff into narrow windrows, in an effort to contain weed seed in a small area. Windrows can be burned, grazed, or if narrow enough, allowed to compost/ rot in place. If the windrows are left alone, the high rates of carbon will drive soil microbes to scavenge for nitrogen, which subsequently immobilizes plant available nitrogen. Low available nitrogen adds to a crowded, competitive, and less-than-ideal environment for a large number weed individuals that otherwise thrive in high-nitrogen environments. Although this reduces the overall area for the crop, the tradeoff is reduced weed pressure in the rest of the field. This method is improved by the use of controlled-traffic farming, which ensures that the chaff lines end up in the same area after every harvest (maintaining the competitive environment and containing the weed seed). The material in the windrows can also be destroyed with burning or by grazing. Burning in windrows has been shown to greatly reduce the survival rate of Italian ryegrass seeds, while additional studies have shown that other species of ryegrass have a roughly 10% survival rate in ruminant stomachs. However, grazing and burning, particularly in the context of California’s wildfire risks, have their own understandable challenges associated with them.
Chaff lining/ Chaff tramlining – This technique is similar to narrow windrowing, but in this case only the chaff is funneled into a narrow area and straw is spread throughout the field as normal. Chaff can also be moved to the sides of the combine (using a lateral conveyor belt), being deposited under the path of the wheels (this process is referred to as “tramlining”). Controlled traffic farming ensures that the seed is concentrated in the same place every year. In the case of tramlining, tractor wheels run over the weedy areas with every field operation, ensuring that any weed seeds that germinate end up growing in compacted, competitive, and highly-trafficked soil.
Direct Baling – Collecting straw and chaff immediately into bales, usually using a tow-along baler behind the combine. After harvest, bales can be moved off the field, thereby removing a large proportion of weed seed before it can disperse into the soil. However, removal of this much biomass can be problematic for growers with low organic matter soils that otherwise benefit from maintaining residues on the ground.
Integrated impact mills – In these systems, chaff is still ejected back into the field, but only after initially going through a hammer mill that shatters and destroys the seed. High initial equipment investments can cool grower enthusiasm. However, one 2017 report from Australia indicated that 29% of growers considered impact mills to be part of their future operations, indicating that at least some growers consider the benefits to outweigh the costs. Combine compatibility can also be a problem as most of the mills are designed to accommodate the larger combines of the midwest, whereas most California combines are typically optimized for relatively smaller acreage.
Limitations and project work
The caveat to all of this is that in order for HWSC to be effective, fields need to be harvested before weed seeds shatter (falling from the plant to the ground). As of yet the shatter patterns of Italian ryegrass in California are not well known. Additionally, previous research has indicated that Italian ryegrass seed retention at small grains harvest can be highly variable across different locations. For example, researchers from the inland Pacific Northwest have reported Italian ryegrass seed retention rates at harvest of 27-50% whereas a 58% of seed retention has been found in Australia. Furthermore, grains in California are planted at different times of the year and our harvest season occurs at different times of the year relative to Australia (not to mention the Pacific Northwest).
Shatter patterns might well be the same as those in other areas of the world but calling for a full scale HWSC revolution isn’t very useful unless we know that a good amount of the weed seed has not yet shattered in the field when small grain crops are harvested.
In an effort to address this, UC researchers will begin collecting data on the shatter status of Italian ryegrass populations in several areas of the Sacramento Valley leading up to harvest. If we consistently see that a significant portion of the Italian ryegrass seed remains attached to the plant at harvest, then HWSC strategies may offer viable control options for California. Conversely, if ryegrass seed has largely shattered by the time our grain crops are harvested, then California growers may need to consider other options for control.
Of course, the best control strategies for herbicide-resistant weeds still include a mixture of different tools such as: the use of herbicides with different modes of action (including pre-emergent and post-emergent types where possible), the use of diversified crop rotations, and well-timed mechanical control. However, a better understanding of the potential for HWSC in California may give growers an edge in reducing the spread of herbicide resistance.
If growers in Sacramento, Solano, or Yolo County are interested in collaborating with UC Cooperative Extension Agronomists in trials focusing on control of Italian ryegrass in small grain crops or have related questions, please reach out to Konrad Mathesius (kpmathesius@ucanr.edu). — By Konrad Mathesius, with contributions from Thomas Gets, Jose Luis Carvalho de Souza Dias, Brad Hanson, and Mark Lundy (UC Cooperative Extension)
A recent report of viral disease on lettuce from our neighbor (Yuma, Arizona) caught our attention since this is highly relevant to our production system (please find information on the first link below). The name of the virus is “Impatient Necrotic Sport Virus” (INSV), which is a tospovirus, similar to the virus that attacks tomato to cause tomato spotted wilt virus symptoms. This virus (INSV) was first reported affecting lettuce crops in Salinas Valley of California in 2006. Subsequently, it was reported to cause crop loss in 2012 and 2015 in the same area. This virus is transmitted by western flower thrips (Frankliniella occidentalis), which is very common and abundant in the low desert region. Early symptoms of infection by INSV are brown to dark spots and dead (necrotic) areas on leaves, which is often mistaken as chemical burn as shown in the picture below on the left-hand side (Photo Credit: Steven T. Koike, UCANR). As the disease progress, multiple leaves could be affected and result in distorted, twisted and dwarf plants (picture on the right). Most of the lettuce types are susceptible to this virus. Several weed species also believed to be the hosts of this virus. Thrips, that also feed on the alternate host weeds can facilitate INSV transmission to lettuce and other crops.
The good news is that this virus has not been reported from Imperial Valley to our best knowledge. However, we must keep an eye on anything unusual, especially the symptoms shown in the pictures below. 
If you observe similar symptoms on your lettuce or related crops, please bring to our attention, contact us at (442) 265-7700 or bring the sample to our office, 1050 E Holton Road, Holtville, CA 92250.
For more information:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=7309
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=17351
-By Apurba Barman & Oli Bachie, UC Cooperative Extension
Apurba Barman joined UC Cooperative Extension as low desert integrated pest management advisor on Jan. 11, 2021. He will be headquartered at the UCCE Imperial County office, which adjoins the UC Desert Research and Extension Center in Holtville.
“I am very excited for my new role as an IPM advisor based in Southern California and for the opportunity to serve one of the most important vegetable production regions in the state,” Barman said. “The diversity and intensity of crop production in this region demand targeted research to solve pest management issues and effective extension programs to reach diverse clientele. I feel prepared for this job with my experience and passion to serve the community.”
Barman earned a bachelor’s degree at Assam Agricultural University in India, and master’s degrees in Indiana and at Texas Tech University, Lubbock. In 2011, he completed a doctorate degree at Texas A&M University in College Station, where he developed a research program to understand the extent of damage and management of thrips in the Texas High Plains region.
Barman comes to UC Cooperative Extension from the University of Georgia, where he led a whitefly monitoring and management progress across cropping systems in the southern region the state.
Barman can be reached at (209) 285-9810 and akbarman@ucanr.edu. His Twitter handle is @Ento_Barman.
Biopesticides contain active ingredients of natural or biological origin that include plant extracts, microorganisms, microbial metabolites, organic molecules, minerals, or other such natural materials that have pesticidal properties. Pests such as herbivorous arthropods, pathogens, parasitic nematodes, mollusks, rodents, and weeds cause significant crop damage when they are not managed. Pest suppression is a critical part of crop production to maintain plant health, prevent yield losses, and optimize returns. As agriculture advanced from subsistence farming to a global enterprise, crop protection also evolved over millennia. When farming was less organized, nature maintained a balance and provided solutions initially. Then natural solutions were actively implemented until industrialization led to the use of synthetic inputs in the 20th century. While synthetic fertilizers and pesticides contributed to a tremendous improvement in the yield potential, the indiscriminate use of some of them and the resulting damage to the environment and human health steered food production in the recent past towards organic farming with the use of nature-based solutions.
Although biopesticides have been around for a few decades, the growth of organic farming gave an impetus to the biopesticide industry during the past few years resulting in the development of new active ingredients and improved formulations. Now, biopesticides are considered an important part of integrated pest management (IPM) strategies in both organic and conventional systems. With a considerable industry investment in research and development, the quality and efficacy of biopesticides have also significantly improved. This has also contributed to optimizing the cost of some formulations. However, there is still a need to fill the knowledge gaps in biopesticides and their use. Depending on the active ingredient, the mode of action for biopesticides, their target pests, their storage and handling, and the use strategies are quite diverse, and a thorough understanding of these aspects is critical for their successful use. As emphasized in the new IPM model (Dara, 2019), while biopesticide use is an integral part of crop protection, understanding the pest biology, using biopesticides appropriate for the target life stage of the pest, applying them at the right time and rate using the right technology, avoiding incompatibility issues, building and sharing effective use strategies, and continuously investing in research and outreach are essential elements of biopesticide use. Biopesticides also play an important role in insecticide resistance management (IRM) to address resistance issues associated with synthetic pesticides. This article provides an overview of various biopesticide categories and general strategies for their successful use for IPM and IRM.
Biopesticides can be used for managing arthropod pests, bacterial or fungal pathogens, plant-parasitic nematodes, weeds, and snails and slugs. Some formulations or active ingredients have multiple roles and can be effective against more than one category of pests. While some active ingredients are very specific to a particular pest or related species, others have a broad-spectrum activity. Based on the source, biopesticides can be placed in four broad categories: i) botanicals, ii) microbials, iii) toxins, and iv) minerals and other natural materials.
Botanical extracts: Plants are a rich source of numerous phytochemicals or secondary metabolites that have a wide range of properties including pesticidal activity. Acids, alkaloids, flavonoids, glycosides, saponins, and terpenoids in plant extracts or oils obtained from seeds and other plant parts are some of the compounds present in various biopesticides (Pino et al., 2013). Azadirachtin, BLAD (polypeptide from sweet lupine seeds), citric acid, essential oils, pyrethrins, soybean oil, and extract of the giant knotweed are used for their acaricidal, insecticidal, fungicidal, nematicidal, or herbicidal properties.
Microbials: Some of the microbial pesticides have live microorganisms (such as entomopathogens, Bacillus spp., Streptomyces spp., and Trichoderma spp.) while others (such as Burkholderia rinojensis and Chromobacterium subtsugae)have heat-killed microorganisms and fermentation solids as the active ingredients. Entomopathogenic microorganisms [Bacillus thuringiensis (bacterium), Beauveria bassiana and Cordyceps fumosorosea (fungi), Heterorhabditis spp. and Steinernema spp. (nematodes), and granuloviruses and nucleopolyhedroviruses] primarily kill their hosts through infection; microbe-based fungicides antagonize plant pathogens through competitive displacement and production of toxic metabolites; nematophagous fungi parasitize plant-parasitic nematodes; and plant pathogenic bacteria, fungi, and viruses infect and suppress weeds. Bacteriophages, which are viruses that parasitize bacteria, are used against the plant pathogenic species of Clavibacter, Erwinia, Pseudomonas, Xanthomonas, Xylella, and other genera.
Toxins and other organic molecules: There are multiple examples of toxic organic molecules derived from various organisms. Avermectins from the bacterium Streptomyces avermitilis and spinosad from the bacterium Saccharopolyspora spinosa, strobulurin from the mushroom Strobuluris tenacellus, and cerevisane from the yeast Saccharomyces cerevisae are some of the microbial toxins that are effective against insects, plant-parasitic nematodes, or snails and slugs. A venom peptide from the Blue Mountains funnel-web spider, Hadronyche versuta, from Australia is a recently developed insecticide active ingredient with its unique mode of action class. Chitosan, a polysaccharide from the exoskeleton of shellfish, is a fungicide.
Minerals and other natural materials: Diatomaceous earth, mineral oil, and minerals such as sulfur are used for controlling multiple categories of pests. Potassium salts of fatty acids of plant or animal origin, known as insecticidal soap, have insecticidal and fungicidal properties. Organic acids such as acetic acid and citric acid are derived from plants and have fungicidal and herbicidal properties. Since these are different from other botanical extracts, they are placed in this category.
Except for the microbial pesticides that have live microorganisms, most biopesticides have chemical molecules of microbial, fungal, botanical, or mineral origin and work through various modes of action similar to synthetic pesticides. Several synthetic pesticides are developed from natural molecules. Abamectin, pyrethroids, neonicotinoids, spinetoram, and storbulurins are synthetic analogs based on avermectins, pyrethrins, nicotine, spinosad, and strobulurin, respectively, and were developed for improved stability, safety, or ease of commercial-scale production.
Integrated pest management and resistance management: Biopesticides are very diverse in their origin and mode of action and have been successfully used in several cropping systems for managing a variety of pests. They have complex interactions with plants, soil microbiota, pests, and environmental conditions. It is critical to have a good understanding of the source of biopesticides and how they act on their target pests. Certain biopesticides may have special storage and handling requirements or tank-mixing restrictions. It is essential to refer to the manufacturer’s guidelines or label instructions to avoid incompatible tank-mix combinations, understand proper application sequences, and to store, transport, and apply under unfavorable conditions. While it is very important to use biopesticides as a part of the IPM program and tools for IRM, caution is warranted to avoid repeated use of the same or a similar type of biopesticide. Pests can develop resistance to biopesticides just as they do to synthetic pesticides (Dara, 2020).
Strategies for using biopesticides: From the seed or transplant treatment to soil or foliar application, biopesticides can be used throughout crop production. Certain combinations can have an additive or a synergistic effect on pest suppression. At the same time, certain inputs or practices can negatively impact biopesticide efficacy. For example, alkaline tank-mix components breakdown the protein coat of entomopathogenic viruses and Bacillus thuringiensis. Botanical oils can be incompatible with cold water. Some fungicides such as captan and thiram are incompatible with entomopathogenic fungi like Beauveria bassiana while several others are compatible (Dara et al., 2014).
Investing in biopesticides: Environmental safety and resistance development are two major concerns for excessive use of synthetic pesticides and incorporating biopesticides into IPM will help address both issues. Substituting biopesticides for synthetic pesticides will reduce the total amount of the latter during a production season and their potential negative impact on the environment and human health. Several biopesticides are not harmful to pollinators and in some production systems, pollinators are used to deliver biopesticides to the crops they pollinate. Adding biopesticides to the standard crop protection program will also increase pest control efficacy. Additionally, by not continuously using synthetic pesticides, the risk of resistance will be reduced and thus their efficacy will continue to be maintained. Although some biopesticides can be more expensive than synthetic pesticides, investing in them will be a good strategy for both the short-term benefit of effective pest suppression and the long-term benefit of a healthy and resilient ecosystem. Since pests do not have boundaries, area-wide implementation of good agricultural practices with a balanced use of synthetic and natural inputs is necessary for maintaining the productivity of the cropping systems.
Productive collaborations among the pesticide industry, researchers, extension educators, and the grower community are critical for successfully using biopesticides for sustainable food production. While research helps to develop effective formulations and their use strategies, outreach helps with the implementation of those strategies. — By Surendra K. Dara, UC Cooperative Extension Advisor, Entomology & Biologicals
California’s $86 million date industry produces more than half of the nation’s dates. Most of the fruit is grown in the arid Coachella Valley. Despite efforts by growers to conserve water, data was lacking on date palms’ actual water use to refine the best irrigation management for the crop until a recent research project led by Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial and Riverside counties.
“California dates are grown in the hottest and most arid climate in North America and require substantial amounts of water in order to bring a successful crop to fruition,” Albert Keck, Coachella Valley date grower and chairman of the California Date Commission, wrote in a letter of support for this project. “In addition, there is scant modern research specifically and technically focused on growing dates in North America.”
Montazar said there is a lack of irrigation management information on date palms worldwide.
“The information developed in this study is expected to have a worldwide impact,” he said.
To determine the evapotranspiration rate and crop coefficients for California date palms, Montazar teamed up with scientists at UC Davis, California Department of Water Resources, USDA Agricultural Research Service, and USDA Salinity Laboratory.
The experiment was carried out in six date orchards in the Coachella and Imperial valleys. The sites represent various soil types and conditions, irrigation management practices, canopy characteristics, and the most common date cultivars in the region.
“The findings of the project indicate that there is considerable variability in date palm consumptive water use, both spatially and temporally,” Montazar said. In other words, the amount of water the trees use varies considerably depending on each site’s growing conditions.
He estimated the water needs for date palms planted in different soil types in the low desert region.
“Growers will be able to use the science-based information and tools developed by this project to determine their date palm water needs and optimize the efficiency of water and fertilizer use in their groves,” Montazar said.
The peer-reviewed article “Determination of Actual Evapotranspiration and Crop Coefficients of California Date Palms Using the Residual of Energy Balance Approach” is published in the journal MDPI Waterat https://www.mdpi.com/2073-4441/12/8/2253.
“With a large quantity of new date plantings in the region, coupled with increasingly limited water resources in the Colorado River Basin Watershed, the knowledge anticipated to be developed by this research project has the potential to yield large dividends through not only improved water use efficiency, but also best management practices and crop quality,” said Keck of the California Date Commission.
Although the research focused on Coachella Valley dates, Montazar said the results are likely to be useful to growers who have orchards with similar varieties, irrigation practices, and canopy and soil features in other locations.
Montazar’s co-authors are Robert Krueger of the USDA-ARS National Clonal Germplasm Repository for Citrus and Dates; Dennis Corwin of USDA-ARS U.S. Salinity Laboratory; Alireza Pourreza UC Cooperative Extension specialist based at UC Davis Department of Biological and Agricultural Engineering; Cayle Little of California Department of Water Resources; Sonia Rios, UC Cooperative Extension advisor in Riverside County; and Richard L. Snyder UC Cooperative Extension specialist emeritus in the UC Davis Department of Land, Air and Water Resources.
The date palm irrigation project was funded by the CDFA Specialty Crop Block Grant Program. — By Pamela Kan-Rice, UCANR