We sequenced and comprehensively analysed the genomic architecture of 98 fluorescent pseudomonads isolated from different symptomatic and asymptomatic tissues of almond and a few other Prunus spp. Phylogenomic analyses, genome mining, field pathogenicity tests, and in vitro ice nucleation and antibiotic sensitivity tests were integrated to improve knowledge of the biology and management of bacterial blast and bacterial canker of almond. We identified Pseudomonas syringae pv. syringae, P. cerasi, and P. viridiflava as almond canker pathogens. P. syringae pv. syringae caused both canker and foliar (blast) symptoms. In contrast, P. cerasi and P. viridiflava only caused cankers, and P. viridiflava appeared to be a weak pathogen of almond. Isolates belonging to P. syringae pv. syringae were the most frequently isolated among the pathogenic species/pathovars, composing 75% of all pathogenic isolates. P. cerasi and P. viridiflava isolates composed 8.3 and 16.7% of the pathogenic isolates, respectively. Laboratory leaf infiltration bioassays produced results distinct from experiments in the field with both P. cerasi and P. syringae pv. syringae, causing significant necrosis and browning of detached leaves, whereas P. viridiflava conferred moderate effects. Genome mining revealed the absence of key epiphytic fitness-related genes in P. cerasi and P. viridiflava genomic sequences, which could explain the contrasting field and laboratory bioassay results. P. syringae pv. syringae and P. cerasi isolates harboured the ice nucleation protein, which correlated with the ice nucleation phenotype. Results of sensitivity tests to copper and kasugamycin showed a strong linkage to putative resistance genes. Isolates harbouring the ctpV gene showed resistance to copper up to 600 μg/ml. In contrast, isolates without the ctpV gene could not grow on nutrient agar amended with 200 μg/ml copper, suggesting ctpV can be used to phenotype copper resistance. All isolates were sensitive to kasugamycin at the label-recommended rate of 100μg/ml.

In California, the most significant insect pest of almonds and pistachios is the navel orangeworm, Amyelois transitella (Walker) and is a pest of walnuts. This pest attacks the nuts and infestation is associated with aflatoxin contamination. While there are multiple integrated pest management (IPM) practices available, anecdotal evidence suggests that not all tools are equally utilized. To understand current industry practices and barriers to adoption, the authors surveyed tree nut growers and industry professionals across 7 University of California Cooperative Extension meetings in California's Central Valley. Findings indicate that as managed acres decreased, participants were less likely to report using as many IPM tools, and pest control advisers reported higher use of multiple practices compared to orchard owners and managers. Key barriers to adoption varied by practice and included high economic costs, low labor availability, environmental conditions, and/or timing constraints. Many respondents were skeptical of the efficacy of mating disruption, a relatively new strategy compared to other IPM tools. Finally, a cluster analysis identified thirteen aggregate grower profiles. Groups primarily differed in their use of monitoring practices, although some groups were also less likely to use sanitation or pesticides. Two groups were distinguished as "early adopters" through their use of mating disruption and/or ovibait traps. These findings document variability in adoption of IPM practices for A. transitella in tree nuts. Identification of the primary barriers and constraints for specific grower groups will inform research and extension efforts to further promote adoption of key IPM strategies.

The black fig fly, Silba adipata McAlpine (Diptera: Lonchaeidae), is a Mediterranean insect that exclusively reproduces on figs, Ficus carica L. (Rosales: Moraceae). Widely considered a pest of figs throughout southern Europe, North Africa, and the Middle East, S. adipata was recently discovered infesting figs throughout southern California, representing the first report of this pest in the United States. Here, we provide background information on the distribution, biology, ecology, monitoring, and management of this pest, as well as outline research and extension efforts that have been catalyzed by this recent invasion. California accounts for a majority of both fresh and dried fig production in the United States. To date, S. adipata infestations have been limited to orchards in coastal and southern California, whereas most commercial fig production takes place in the inland Central Valley region. Better knowledge of temperature thresholds is currently needed to estimate potential range expansion to these more inland regions of the state.

Almond canker diseases are destructive and can reduce the yield as well as the lifespan of almond orchards. These diseases may affect the trunk and branches of both young and mature trees and can result in tree death soon after orchard establishment in severe cases. Between 2015 and 2018, 70 almond orchards were visited throughout the Central Valley of California upon requests from farm advisors for canker disease diagnosis. Two major canker diseases were identified, including Botryosphaeriaceae cankers and Ceratocystis canker. In addition, five less prevalent canker diseases were identified, including Cytospora, Eutypa, Diaporthe, Collophorina, and Pallidophorina canker. Seventy-four fungal isolates were selected for multilocus phylogenetic analyses of internal transcribed spacer region ITS1-5.8S-ITS2 and part of the translation elongation factor 1-α, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase gene sequences; 27 species were identified, including 12 Botryosphaeriaceae species, Ceratocystis destructans, five Cytospora species, Collophorina hispanica, four Diaporthe species, two Diatrype species, Eutypa lata, and Pallidophorina paarla. The most frequently isolated species were Ceratocystis destructans, Neoscytalidium dimidiatum, and Cytospora californica. Pathogenicity experiments on almond cultivar Nonpareil revealed that Neofusicoccum parvum, Neofusicoccum arbuti, and Neofusicoccum mediterraneum were the most virulent. Botryosphaeriaceae cankers were predominantly found in young orchards and symptoms were most prevalent on the trunks of trees. Ceratocystis canker was most commonly found in mature orchards and associated with symptoms found on trunks or large scaffold branches. This study provides a thorough examination of the diversity and pathogenicity of fungal pathogens associated with branch and trunk cankers of almond in California.