California Department Of Food And Agriculture Research Articles

Limitations of Reporting Requirements under California's Livestock Antimicrobial Restriction Law.

Antimicrobial use in livestock production is considered a key contributor to growing antimicrobial resistance in bacteria. In 2015, California became the first state to enact restrictions on routine antimicrobial use in livestock production via Senate Bill 27 (SB27). SB27 further required the California Department of Food and Agriculture (CDFA) to collect and disseminate data on antimicrobial use in livestock production. The goal of this report is to assess whether CDFA's data release allows us to evaluate how antimicrobial use changed after the implementation of SB27. We combine the CDFA data with feed drug concentration ranges from the Code of Federal Regulation to evaluate the spread of plausible antimicrobial use trends. We also estimate antimicrobial consumption rates using data from the National Agricultural Statistical Service (NASS) and compare these to changes in medicated feed production reported by the CDFA. We show that CDFA's reported data are insufficient to reliably estimate whether antimicrobial usage has increased or decreased, most notably because no information is provided about the mass of antimicrobials approved for use or medicated feed drug concentrations. After incorporating additional external data on feed drug concentrations, one can at best provide uninformative bounds on the effect of SB27. We find some evidence that antimicrobial use has decreased by incorporating data on national sales of antimicrobials for food-producing animals, but the weakness of this inference underlines the need for improved data collection and dissemination, especially as other states seek to implement similar policies. We provide recommendations on how to improve reporting and data collection under SB27. https://doi.org/10.1289/EHP13702.

First report of Phytophthora ramorum on Cotoneaster sp. in the USA.

Cotoneaster (Rosaceae) is a genus of woody plants native to the Palearctic region which includes popular ornamental plants; some are invasive in parts of the USA. In May 2022 symptomatic leaves were detected on Cotoneaster pannosus (Silverleaf Cotoneaster) in Marin County, California (37.89165, -122.56755 ), an area infested heavily by Phytophthora ramorum, causal agent of Sudden Oak Death. Symptoms consisted of dark brown necrotic spots mostly near the tips and sometimes on the margin of the leaves, covering less than half of the leaf surface; no die-back or symptoms on twigs were detected. Diseased leaves were surface-sterilized with 70% ethanol, washed twice with de-ionized water, and placed on PARPH(V8) media. Two Phytophthora ramorum like isolates (NORS058 and NORS059) were obtained from different leaf samples from the same tree and the internal transcribed spacer (ITS) region was sequenced. Both sequences were deposited in GenBank (OR224345 and OR224346). NORS058 and NORS059 showed 99.88% and 99.75% sequence identity to P. ramorum strain Ex-type CPHST BL 55G (MG865581.1). Detached leaves of C. pannosus and C. lacteus (Milkflower Cotoneaster) were inoculated with mycelial plugs of P. ramorum NORS058, and incubated at 20°C. Both species developed necrotic leaf spots seven days post inoculation (dpi). Sporulation of the pathogen was observed on symptomatic leaves of C. lacteus. P. ramorum was reisolated from the symptomatic leaf tissue from both Cotoneaster species. Pathogenicity tests were also performed on whole plants of C. dammeri (Bearberry Cotoneaster) using the strain NORS058. Five plants each were inoculated using three different methods: 1) a zoospore solution (concentration 2.5 x10E5 spores/mL) were sprayed on the plant surface until run off. Ten leaves per plant were wounded with a needle, the remaining leaves were not wounded; 2) 200 µL of the zoospore solution in a PCR tube were attached to 5 leaves of each plant; and 3) 10 mL of the zoospore solution was drenched into the potting mix of the five plants. Control plants were treated as above but with water instead of the zoospore solution. Leaf spots developed 7 dpi on plants sprayed with zoospores on wounded leaves; and 10 dpi on plants treated with zoospores in the tube. P. ramorum was reisolated from symptomatic leaves treated with the first two methods mentioned above. Plants treated with a soil drench did not develop symptoms on the aerial parts or on roots that were sampled 50 dpi. Tests using AGDIA- immunostrips of the roots were negative. Control plants showed no aerial or root symptoms. To our knowledge, this is the first report of P. ramorum occurring on Cotoneaster in the USA. Previously, inoculation of detached leaves of C. dammeri and C. horizontalis with P. ramorum in Serbia resulted in symptom expression (Bulajić et al. 2010). P. ramorum was reported from a Cotoneaster sp. in the UK in 2010, but no further information were presented (FERA 2015). The tree sampled in 2022 showed symptoms again in spring 2023 and official regulatory samples were taken by the CDFA (California Department of Food and Agriculture) and confirmed by the USDA. During a survey in 2023, more symptomatic Cotoneaster plants were detected in Marin County, California, indicating Cotoneaster might play a role in the epidemiology of the disease.

Outreach Efforts to Prevent Newcastle Disease Outbreaks in Southern California.

In May 2018, an outbreak of virulent Newcastle disease (vND) affected backyard and commercial premises in Southern California. The re-occurrence of these outbreaks since the 1970s suggests that some poultry communities may not have reliable and stable resources available regarding biosecurity and disease prevention. Therefore, staff at the University of California, Davis (UCD) School of Veterinary Medicine (SVM), and the California Department of Food and Agriculture (CDFA) began organizing educational events and learning more about the gamefowl breeder community through a needs assessment exercise, during which local feedstores and neighborhoods were also visited. Focus groups were organized with breeders in various cities within the regional quarantine area, established by the CDFA during the vND outbreak. The focus groups were aimed at creating open communication networks with gamefowl breeders in the affected area, as well as to learn about their current sources of information, learning preferences, and current management practices. With the input from gamefowl breeders, as well as funding and input from the CDFA and the United States Department of Agriculture (USDA), a quality assurance program called the “Gamefowl Wellness Program” was established. Educational content was created and published through the UCD Gamefowl Wellness Program poultry health website. Additionally, with the help of the CDFA, the USDA, and pharmaceutical companies, Newcastle disease vaccines and training for their application were provided to feedstores with gamefowl breeder clientele. Nurturing trust with these poultry communities allowed us to receive the information needed to develop effective outreach strategies that could better serve them. Responding to community concerns might be a way to garner the trust necessary to prevent or at least promptly detect foreign animal disease outbreaks.

Web crawling of social media and related web platforms to analyze backyard poultry owners responses to the 2018-2020 Newcastle Disease (ND) outbreak in Southern California.

As social media becomes an ever-increasing staple of everyday life and a growing percentage of people turn to community driven platforms as a primary source of information, the data created from these posts can provide a new source of information from which to better understand an event in near real time. The 2018-2020 outbreak of Newcastle Disease (ND) in Southern California is the third outbreak of ND in Southern California within a 50-year time span. These outbreaks are thought to be primarily driven by non-commercial poultry (i.e. backyard and game fowl) in the region. Here we employed a commercial 'web crawling' tool between June of 2018 and July of 2020 which encompassed the majority of the outbreak in order to collect all available online mentions of 'virulent Newcastle Disease' (vND), the terminology commonly used by the California Department of Food and Agriculture (CDFA), United States Department of Agriculture (USDA), and the general public, in relation to the outbreak. A total of 2498 posts in English and Spanish were returned using a Boolean logic-based string search. While the number of posts was relatively small, their impact as measured by the number of visitors to the website and the number of people viewing the post (where provided) was much larger. Posts with negative sentiment were found to have a larger audience relative to posts with a positive sentiment. In addition, posts with negative sentiment peaked in May of 2019 which preceded the formation of the anti-depopulation group Save Our Birds (SOB). As the usage and impact of social media grows, the ability to utilize tools to analyze social media may improve both response and outreach-based strategies for various disease outbreaks including vND in Southern California which has a large non-commercial poultry population.

The potential threat of branched broomrape for California processing tomato: A review

Branched broomrape (Phelipanche ramosa), a parasitic weed that was the focus of a $1.5 million eradication effort four decades ago in California, has recently re-emerged in tomato fields in several Central Valley counties. Processing tomatoes are important to the California agricultural economy; the state produced over 90% of the 12 million tons of tomatoes grown in the United States in 2018. Branched broomrape is listed as an “A” noxious weed by the California Department of Food and Agriculture (CDFA); discovery of broomrape in California tomato fields leads to quarantine and crop destruction without harvest, resulting in significant economic loss to growers. In countries where broomrape is common, yield reductions caused by this parasitic weed can range from moderate to 80%, depending upon the infestation level, host and environmental conditions. Developing a detailed understanding of the biology of this weed under local conditions is an important step towards developing effective management plans for California. In this review, we discuss branched broomrape in the context of California production systems, particularly of tomato. We also discuss the potential management practices that could help to prevent or reduce the impacts of branched broomrape in tomatoes and other host crops.

Outbreak of rabbit hemorrhagic disease virus 2 in the southwestern United States: first detections in southern California.

An outbreak of rabbit hemorrhagic disease virus 2 (RHDV2)-associated disease occurred in the southwestern United States following its first detection in New Mexico in March 2020. The disease spread throughout several states and was diagnosed for the first time in California on May 11, 2020, in a black-tailed jackrabbit (Lepus californicus). The following day, the California Department of Food and Agriculture (CDFA) issued an order banning the entrance into California of several lagomorph species and their products from any state in which the disease had been detected in the last 12 mo. RHDV2 is a threat to wild lagomorph species in California, including the endangered riparian brush rabbit (Sylvilagus bachmani riparius). Therefore, the California Department of Fish and Wildlife (CDFW) started tracking any mortality event in wild lagomorph populations. As of August 9, 2020, RHDV2 had been detected in wild and domestic lagomorphs of several counties in southern California that were submitted to the California Animal Health and Food Safety laboratory system by the CDFA or the CDFW. These positive cases included 2 additional black-tailed jackrabbits and 3 desert cottontail rabbits (Sylvilagus audubonii). In addition, the infection spilled over to domestic populations, whereby it was confirmed on July 10, 2020, in a domestic rabbit (Oryctolagus cuniculus).

Action Plan for Asian Citrus Psyllid and Huanglongbing (Citrus Greening) in California

This document sets forth the California Department of Food and Agriculture (CDFA), Citrus Pest and Disease Prevention Division (CPDPD) statewide Action Plan for Asian citrus psyllid (ACP) and Huanglongbing (HLB). This document details the program implemented by CPDPD to sustain and protect California’s commercial citrus production, residential citrus plantings, and natural resources.

Comparação entre índices de potencial de lixiviação para agrotóxicos utilizados na Sub-Bacia do Natuba, Vitória de Santo Antão-Pernambuco

A contaminação ambiental por agrotóxicos vem sendo crescentemente abordada por diversos autores na literatura e discutida pela sociedade civil, por causa de suas externalidades negativas. Este estudo visou calcular e comparar o potencial de lixiviação e contaminação dos princípios ativos de agrotóxicos que são utilizados na sub-bacia hidrográfica do rio Natuba, município de Vitória de Santo Antão-Pernambuco. Para tanto, utilizou-se índices que se propõem a avaliar a capacidade de um determinado princípio ativo de agrotóxico lixiviar ou ser transportado no meio ambiente, a saber: Groundwater Screening Index (GSI), Groundwater Ubiquity Score (GUS), Relative Leaching Potential Index (RLPI), Leaching IndeX (LIX), Leaching Index (LEACH) e critério da California Departament of Food and Agriculture (CDFA). Os dados dos índices GSI, GUS, LIX, LEACH e RLPI demonstraram valores semelhantes por meio da análise de variâncias, ou seja, cada índice tende a indicar, em sua faixa de valores, a mesma propensão de lixiviação do agrotóxico. Assim, ao comparar os enquadramentos de cada um dos agrotóxicos, destacaram-se, pelo risco ambiental: picloram, hexazinone, clorantraniliprole, carbofurano, thiamethoxam, 2,4 D sal dimetilamina, imidacloprido, azoxistrobina, cartape, dicloreto de paraquate. Dessa forma, deve-se evitar o uso desses ingredientes ativos e substituí-los por outros com menor potencial de lixiviação, visando à proteção da área.

First Report of Citrus viroid V Naturally Infecting Grapefruit and Calamondin Trees in California.

The Citrus Clonal Protection Program–National Clean Plant Network, University of California, Riverside (UCR), received citrus budwood samples in June 2016 from the California Department of Food and Agriculture (CDFA) for virus and viroid testing under the mandatory California (CA) §3701 Citrus Nursery Stock Pest Cleanliness Program. Samples originated from nonsymptomatic budwood sources, two redblush grapefruit (RG) (Citrus paradisi Macfadyen) and four variegated calamondin (VC) (C. madurensis Lour.), and were found in a nursery in Tulare County, CA. TRIzol-extracted RNA was tested with a SYBR green I reverse transcription quantitative polymerase chain reaction (RT-qPCR) for the universal detection of citrus viroids (Osman et al. 2017). Amplicons with melting temperatures similar to the Citrus viroid V (CVd-V) control (Vidalakis and Wang 2013) were produced in 50% of the RG and 25% of the VC samples. Citron (C. medica L.) Arizona 861-S-1 indicators were graft-inoculated with RG and VC blind buds (two citrons each) and maintained under warm greenhouse conditions (27 to 41°C). By 8 months, all citrons had developed mild stunting and leaf bending coupled with midvein necrosis, indicative of viroid infection. Sequential polyacrylamide gel electrophoresis of the symptomatic citrons identified circular and linear viroid-like RNAs with electrophoretic mobility similar to CVd-V. RT-PCR with primers specific for the full CVd-V genome (Wang et al. 2013) produced amplicons of the expected size of 294 bp from both the RG and VC samples and from the four indicator citrons. Cloning and sequencing of the RT-PCR CVd-V amplicons produced complete viroid genome sequences (GenBank MF477857 to MF477876). The RG isolates (MF477857 to MF477866) had 99% similarity with the KM isolate (JQ348924, Pakistan), with one nucleotide change (A₆₅ > U). The VC isolates (MF477867 to MF477876) had 99% similarity with the MO isolate (JQ348925, Pakistan), with two nucleotide changes (G₆₉ > A and A₂₅₁ > U). To further test the infectivity of the identified viroid, RNA extracts from the RG and VC graft-inoculated citrons were slash-inoculated onto four new citrons budded on rough lemon (C. jambhiri Lush.) rootstock. All citrons developed symptoms, and CVd-V was identified with RT-PCR, cloning, and sequencing. The CVd-V identification results were independently verified by CDFA’s Plant Pest Diagnostic Center, and the original source trees were destroyed. CVd-V was first reported in Spain (Serra et al. 2008a) and has been detected in various samples including a source from UCR, but the source of the UCR field material was not recorded (Serra et al. 2008b). This note reports the natural occurrence of CVd-V in CA and corroborates the CVd-VCᴬ variant report from the UCR source (Serra et al. 2008b). This note also demonstrates the importance of regulatory testing of propagative materials and elimination of infected citrus germplasm source trees to prevent the spread of viroids into commercial citrus.

Mark Hoddle: Smiting weevils

Profile Mark Hoddle: Smiting weevils flying insects — have shown that the weevils have the potential to fly tens of miles in a day. The weevil is also known to carry a pathogen known as the red ring nematode which also infects the Canary Island palm, making weevil infestations particularly deadly. The nematode hasn’t yet been found on the weevils trapped in the United States, but Hoddle says it’s probably only a matter of time until it appears. So far, the Hoddle family monitoring program hasn’t found any South American palm weevils north of San Diego County. But the insect appears to be well-entrenched in some areas, such as the Sweetwater River Trail, a natural area near Bonita in San Diego County where many palms grow wild and unmanaged, amidst thickets of willows. Areas like this provide reservoirs for the weevil population to grow and spread into new areas. As one part of their monitoring effort, the Hoddles have assigned GPS coordinates to 300 trees in and near the Sweetwater River Trail area, and are monitoring them to better understand the dynamics of the weevil’s spread. Hoddle will be using drone- mounted cameras to do regular monitoring of the trees in in- fested areas, many of which are difficult to reach. Hoddle has been working with the California Department of Food and Agriculture (CDFA) to draw attention to the infesta- tion, yielding media coverage all the way up to an article in the New York Times. People finding a South American palm weevil UC Riverside entomology specialist Mark Hoddle and his son, Nicholas, set weevil traps along the Sweetwater River Trail in San Diego County, a natural area where weevils have infested many unmanaged Canary Island palms. http://calag.ucanr.edu • JANUARY–MARCH 2017 21 Christina Hoddle Mike Lewis M ark Hoddle’s research article in this issue documents a major achievement in invasive species control — a successful eradication, in this case of the Asian palm weevil, Rhynchophorus vulneratus, from Laguna Beach. Hoddle, a UC Riverside-based entomology specialist and di- rector of the Center for Invasive Species Research (CISR), is now working to address another weevil infestation. This time, the invader is Rhynchophorus palmarum, the South American palm weevil. Over decades, the insect has steadily increased its range northward in Mexico, enabled by abundant plantings of Canary Island palms which the weevil infests in irrigated desert areas. These unnatural oases have provided step- ping stones for the weevil through inhos- pitable habitat all the way to California. The South American palm weevil, The South Rhynchophorus palmarum (actual American palm wee- size), infests the Canary Island palm, a vil was first found in common landscape tree in California. the United States in 2011, just north of the border near San Diego. After that detec- tion, a two-year, federally supported trapping program con- cluded that the infestation hadn’t spread beyond San Diego and Imperial counties. After 2013, funding for the trapping effort ran out, leaving no system for monitoring the weevil. After a visit to Tijuana last May, Hoddle found 125 weevil-killed palms in a day of driving around the city with a colleague from Tijuana. After this he de- cided to take matters into his own hands. The following month, he and his wife, Christina — also an entomology researcher at UC Riverside and a co-author on the research paper in this issue — began a family mission to assess the state of the infestation in California. “We are spending a significant amount of our spare time trapping in San Diego,” he said. They bring along their three- year-old son, Nicholas, who likes hunting for the satisfyingly large black weevils. “It was easy to get him on board, because we are looking for super cool big beetles,” said Hoddle, who grew up in New Zealand and has loved hunting for bugs since he was a small boy. Because Canary Island palms are such a ubiquitous part of the California landscape, they could provide food for weevil invasion all the way up to Northern California. Laboratory tests Hoddle has conducted using “flight mills” — treadmills for

Preparing for an uncertain future with climate smart agriculture

Editorial Preparing for an uncertain future with climate smart agriculture by Karen Ross, Secretary, California Department of Food and Agriculture C alifornia is the nation’s leading agricultural state, with 76,400 farms producing more than 400 commodities with a farm-gate value of $54 billion. The mission of the California Department of Food and Agriculture (CDFA) is to promote and protect agriculture. It’s a complex job — and one that is getting more complex as the climate changes. Karen Ross sustainability, build resilience to climate change and reduce greenhouse gas emissions: The State Water Efficiency and Enhancement Program (SWEEP) is an emergency drought program imple- mented at the direction of Gov. Jerry Brown to assist farmers in moving to efficient water irrigation systems that save water, conserve energy and reduce green- house gas emissions. To date, SWEEP has funded 233 projects totaling almost $18 million with $10.5 mil- lion in matching grower funds. The program is built With the current drought in its fourth year, on a strong scientific foundation and supported by a California has already started to experience some of collaborative partnership involving other agencies, the anticipated impacts of climate change. resource conservation districts, the California State With drought, we have seen economic University (CSU) system and UC ANR Cooperative losses including job losses, fallowed land, Extension (UCCE). The academic institutions play and greater demand for a limited amount a key role in providing technical evaluations of ap- of water. A concerted approach is ur- plications for water savings and reductions in energy gently needed to prepare California agri- consumption. culture for future climate change impacts. The Dairy Digester Research and Development One essential approach is embracing Program, launched in 2014, provides incentives for and implementing the concept of climate dairy operations to install manure digesters. Digesters smart agriculture. capture methane from dairy lagoons, allowing the gas Practicing climate smart agriculture to be used to generate electricity. Methane is a short- means following three principles: de- lived climate pollutant that is 28 times more potent veloping agricultural systems that are as a greenhouse gas than carbon dioxide. In 2015, resilient to climate change; reducing CDFA awarded $11.1 million for the development of greenhouse gas emissions from agricul- five digesters at California dairies. Matching funds by ture; and preparing for climate change in a way that developers totaling $19 million were allocated to these keeps farms productive and profitable. projects. The digester program is supported by several I heard a lot about climate smart agriculture during scientific experts from the University of California a recent visit to the Netherlands with a delegation of as well as a technical advisory sub-committee. The agricultural leaders from California. The Netherlands program highlights the many opportunities to use ag- is a leading agriculture distributor in Europe and the ricultural byproducts for multiple benefits, including world’s second largest (after the United States) agri- the generation of electricity. cultural exporter. Climate smart agriculture is already strongly integrated into Dutch economic and food se- curity strategies. Our delegation not only heard about the threats from higher precipitation, but also about how overly dry conditions in the summer threaten the stability of peat dikes, which dry up to the point that they may simply float away, compromising the levee structure in a region where most of the land is below sea level. In California we can prepare for such multi-faceted impacts through our own climate smart agricul- ture initiatives. At CDFA, we have a variety of pro- grams and efforts underway to support agricultural 4 CALIFORNIA AGRICULTURE • VOLUME 70 , NUMBER 1 Evett Kilmartin More-efficient irrigation technologies — like this drip system in an almond orchard in Yolo County — save water, conserve energy and reduce greenhouse gas emissions.

New license plate supports youth agricultural programs

New license plate supports youth agricultural programs

Community air monitoring for pesticides—part 2: multiresidue determination of pesticides in air by gas chromatography, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry

Two multiresidue methods were developed to determine pesticides in air collected in California. Pesticides were trapped using XAD-4 resin and extracted with ethyl acetate. Based on an analytical method from the University of California Davis Trace Analytical Laboratory, pesticides were detected by analyzing the extract by gas chromatography-mass spectrometry (GC-MS) to determine chlorothalonil, chlorthal-dimethyl, cycloate, dicloran, dicofol, EPTC, ethalfluralin, iprodione, mefenoxam, metolachlor, PCNB, permethrin, pronamide, simazine, trifluralin, and vinclozolin. A GC with a flame photometric detector was used to determine chlorpyrifos, chlorpyrifos oxon, diazinon, diazinon oxon, dimethoate, dimethoate oxon, fonophos, fonophos oxon, malathion, malathion oxon, naled, and oxydemeton. Trapping efficiencies ranged from 78 to 92% for low level (0.5μg) and 37-104% for high level (50 and 100μg) recoveries. Little to no degradation of compounds occurred over 31days; recoveries ranged from 78 to 113%. In the California Department of Food and Agriculture (CDFA) method, pesticides were detected by analyzing the extract by GC-MS to determine chlorothalonil, chlorpyrifos, cypermethrin, dichlorvos, dicofol, endosulfan 1, endosulfan sulfate, oxyfluorfen, permethrin, propargite, and trifluralin. A liquid chromatograph coupled to a MS was used to determine azinphos-methyl, chloropyrifos oxon, DEF, diazinon, diazinon oxon, dimethoate, dimethoate oxon, diuron, EPTC, malathion, malathion oxon, metolachlor, molinate, norflurazon, oryzalin, phosmet, propanil, simazine and thiobencarb. Trapping efficiencies for compounds determined by the CDFA method ranged from 10 to 113, 22 to 114, and 56 to 132% for 10, 5, and 2μg spikes, respectively. Storage tests yielded 70-170% recovery for up to 28days. These multiresidue methods represent flexible, sensitive, accurate, and cost-effective ways to determine residues of various pesticides in ambient air.

Asian citrus psyllid and huanglongbing disease threaten California citrus

Research news Asian citrus psyllid and huanglongbing disease threaten California citrus Santa Clara San Benito Merced Madera Fresno Inyo Tulare Monterey Kings San Luis Obispo Kern M.E. Rogers A sian citrus psyllid is slowly spreading in California, and huanglongbing disease (also known as citrus greening) will likely become established in the state, requiring citrus farmers and residents with citrus in their landscapes to become ac- customed to a new reality. “Asian citrus psyllid and huanglongbing dis- ease have played out this way around the world, including in Florida, Texas and other states,” said UC Cooperative Extension specialist Beth Grafton- Cardwell. “There is no reason to believe California will be immune to the natural progression of this dis- ease complex.” The aphid-sized Asian citrus psyllid was first iden- tified in California in 2008 and is currently found in Imperial, San Diego, Los Angeles, Orange, Riverside, and San Bernardino counties. Asian citrus psyllid injects a toxin when it feeds on citrus leaves or stems, causing shoot deformation and plant stunting. Of greater concern is the fact that it vectors the bacterium associated with huanglongbing disease. Every tree infected with the pathogen will suffer a premature death, sometimes in as little as 3 years. But that doesn’t mean UC researchers and UC Cooperative Extension specialists and advisors are Asian citrus psyllid carries the vector of huanglongbing disease, also known as citrus greening. One symptom of the disease is mottling and chlorosis of leaves. giving this serious citrus disease free rein in the Golden State. UC is working with officials from the citrus industry, U.S. Department of Agriculture and California Department of Food and Agriculture (CDFA) to wage an all-out battle. They aim to contain psyllid populations, catch the infection early in order to rapidly remove infected trees, and monitor commercial citrus using geospa- tial technology. Meanwhile, scientists in university laboratories are exploring the trees, the pest and the pathogen at the molecular and genetic levels to find a long-term cure, while advisors are engaging and educating the public to help in the fight against the disease’s spread. Spread of the psyllid San Bernardino In March 2012, huanglongbing disease was de- tected in California for the first time. The multigrafted citrus tree in a Los Angeles County backyard was destroyed, but it is likely there are more infected trees nearby or in other areas. The disease is also spreading Riverside Orange northward in Mexico toward California. The psyllid and disease together present a grave ACP Observations Imperial threat to California’s $2.1 billion citrus industry, the Commercial Citrus San Diego livelihood of citrus farmers and thousands of farm- Counties workers, and the fragile economies in California’s rural citrus belt, extending from San Diego through Asian citrus psyllid total trap count, 2008–2012. The Geographic Information Systems Facility interior and coastal Southern California and up at the UC Kearney Agricultural Research and Extension Center in Parlier has entered a into the San Joaquin Valley. Their presence prevents partnership with the Citrus Research Board and CDFA to develop a statewide citrus mapping database, enabling the citrus industry to make strategic responses to ACP and HLB outbreaks. exports to countries that do not have this pest and To date, the database has mapped 29,865 Asian citrus psyllid detections. disease. The loss of citrus trees in urban areas of Santa Barbara Ventura Los Angeles http://californiaagriculture.ucanr.edu • October–December 2012 127

Characterization of Curtoviruses Associated with Curly Top Disease of Tomato in California and Monitoring for These Viruses in Beet Leafhoppers.

Curly top disease is caused by a complex of curtoviruses (family Geminiviridae), and it continues to plague tomato production in California. To better understand the etiology of curly top of tomatoes in California, polymerase chain reaction (PCR)-based methods were developed and used to characterize the curtoviruses involved, and to monitor for these viruses in the beet leafhopper vector, Circulifer tenellus. From 2002 to 2008, 86 processing and fresh market tomato fields in the Central Valley of California were surveyed for the incidence of curly top symptoms. Representative samples with curly top symptoms were collected from the surveyed fields, as well as from another 24 fields. The incidence of curly top symptoms in most fields ranged from trace (<1%) to low (1 to 5%); however, in 2002, 2003, and 2008, some fields had medium (5 to 20%) or high (>20%) incidences. PCR with general and species-specific primers was used to establish that the predominant species associated with tomato curly top disease were Beet mild curly top virus (BMCTV) and, to a lesser extent, Beet severe curly top virus (BSCTV). The incidence, relative amount, and species of curly top virus in leafhoppers, collected at monthly intervals by the California Department of Food and Agriculture (CDFA) personnel during 2003 to 2008, was also determined. The predominant species detected were BMCTV and BSCTV. The highest incidences of curly top in tomato fields were associated with high populations of leafhoppers (e.g., in 2003 when populations were two times greater than average) having high incidences and levels of curly top virus early in the growing seasons (e.g., March to May 2003 and 2008). Detection of curly top virus in leafhoppers early in the growing season was consistent with acquisition of virus from reservoir hosts in the foothills. However, continued detection of curly top virus in leafhoppers throughout the growing season and development of curly top in late-planted fresh market tomatoes were consistent with the presence of inoculum sources (e.g., weeds or crop plants) in the agricultural areas of the Central Valley. Geographical locations or "hotspots" having higher proportions of curly top virus-positive leafhoppers were identified, which may reveal areas having high concentrations of curly top virus reservoir hosts. The application of these molecular tools has provided new insight into curly top of tomato in California, and may lead to improved curly top management.

The Mediterranean Fruit Fly ( Ceratitis capitata )

after its repeated eradication” (p. 53). These claims are similar to the arguments put forth in letters sent to the Science editor by the late Henry Voss (Voss 1992), then Director of the California Department of Food and Agriculture (CDFA), and the late Steven Saul (Saul 1992), then an entomologist at the University of Hawaii, after my article appeared in 1991. I am disappointed that the “pathways theory” is still being used to account for

Critical Comparison of Humic Acid Test Methods

The colorimetric method and the California Department of Food and Agriculture (CDFA) method of evaluating the humic acid content of five raw humate ores and three humate products were compared to the classical technique of extraction in a dilute base followed by precipitation of humic acid by extract acidification and ash removal by hydrochloric/hydrofluoric acid (HCl/HF) wash. Compared to the classical procedure, the colorimetric and CDFA methods overestimated the humic acid content of the eight samples by 120% and 52%, respectively. Therefore, these procedures do not produce a reliably accurate value for the humic acid contents of humates and products produced using materials extracted from them.

Detection Surveys and Population Monitoring forPseudacysta perseaeon Avocados in Southern California

The avocado lace bug, Pseudacysta perseae (Heidemann) (Hemiptera: Tingidae), is a foliar pest of avocados, and the known distribution of P. perseae includes the Caribbean, the southeastern USA, Mexico, Guatemala, Venezuela and French Guyana (Humeres et al. 2009). Pseudacysta perseae was detected for the first time in California (USA) in Sep 2004 from 2 residential avocado trees in Chula Vista and San Diego in San Diego County (Hoddle et al. 2005). We present surveys that delineate the range of P. perseae in California, selected monitoring sites, and long-term monitoring studies to determine population growth trends from 3 years of population data. Two detection surveys for P. perseae with a pest detection grid system established by the California Department of Food and Agriculture (CDFA) were performed in San Diego County during spring (Mar 20-Jun 30) and fall (Sep 20-Oct 30) of 2006 to delineate the geographic distribution of this pest. The CDFA grid square used for surveys was 2.6 km2. If P. perseae was present, or if avocado trees exhibited possible symptoms characteristic of P. perseae feeding (e.g., large necrotic areas on mature leaves, or trees were defoliated), samples were collected and sent to the San Diego County Department of Agriculture, Weights and Measures' Entomology Laboratory for official determination.

High Levels of Exotic Armored Scales on Imported Avocados Raise Concerns Regarding USDA–APHIS’ Phytosanitary Risk Assessment

Between 1914 and 2007, a quarantine protected California avocado, Persea americana Mill., groves from pests that might be introduced into the state along with fresh, imported avocados. Soon after Mexican avocados were first allowed entry on 1 February 2007, live specimens of several species of armored scales (Hemiptera: Diaspididae) not believed to be present in California were detected on 'Hass' avocados entering the state from Mexico. Initially, the California Department of Food and Agriculture (CDFA) prevented avocados infested with these scales from entering the state or required that they be fumigated with an approved treatment such as methyl bromide. After a Science Advisory Panel meeting in May 2007, U.S. Department of Agriculture-Animal and Plant Health Inspection Service (USDA-APHIS) reaffirmed its position that armored scales on shipments of fruit for consumption (including avocados) pose a "low risk" for pest establishment. In compliance with APHIS protocols, as of 18 July 2007, CDFA altered its policy to allow shipments of scale-infested avocados into the state without treatment. Here, we report on sampling Mexican avocados over an 8-mo period, September 2007-April 2008. An estimated 67 million Mexican Hass avocados entered California over this period. Based on samples from 140 trucks containing approximately 15.6% of this volume of fruit, we estimate that approximately 47.6 million live, sessile armored scales and an additional 20.1 million live eggs and crawlers were imported. We found eight probable species of armored scales in the samples, seven of these are not believed to occur in California; 89.3% of the live scales were Abgrallaspis aguacatae Evans, Watson and Miller, a recently described species. In contrast to the USDA-APHIS opinion, we believe the volume of shipments and levels of live scales they contain present a significant risk to California's US$300 million avocado industry and to other crops that might become infested by one or more of these exotic species.

Peel Fluorescence as a Means to Identify Freeze-damaged Navel Oranges

The use of ultraviolet fluorescence to identify freeze-damaged navel oranges (Citrus sinensis) was evaluated using fruit harvested following a natural freeze that occurred in California in Jan. 2007. Navel oranges were harvested after the freeze from 14 sites that were previously determined to have a slight to moderate amount of freeze damage. The fruit were evaluated for the presence of small yellow spots characteristic of freeze damage that fluoresce when viewed under a ultraviolet-A (365 nm) source and were then cut and rated using a method currently used by the California Department of Food and Agriculture (CDFA) to determine the presence of internal freeze damage. The percentage of freeze-damaged fruit in each lot as determined by the CDFA method ranged from 0% to 89%. The accuracy of classifying fruit as freeze damaged in each lot by peel fluorescence averaged 44%, with the fruit lots containing the greatest amount of freeze damage having the highest classification percentages. False-positives occurred at a lower rate than false-negatives among the lots. Although some fading was evident, the fluorescence persisted and was readily visible for at least 9 weeks after the freeze event. Removal of fruit with ultraviolet peel fluorescence was ineffective in reducing the percentage of damaged fruit within the examined lots. In the second part of the test, eighteen lots of potentially freeze-damaged fruit were obtained from a packing house, immediately evaluated for freeze damage using ultraviolet light, and then after 4 weeks of storage, were evaluated again using the CDFA method. Fruit that had a slight to moderate degree of freeze damage were tasted and evaluated for sensory characteristics. Both methods of freeze damage detection were poorly related to the sensory characteristics.