Cytospora species are destructive canker and dieback pathogens of woody hosts in natural and agroecosystems around the world. In this genus, molecular identification has been limited due to the paucity of multi-locus sequence typing studies and the lack of sequence data from type specimens in public repositories, stalling robust phylogenetic reconstructions. In most cases a morphological species concept could not be applied due to the plasticity of characters and significant overlap of morphological features such as spore dimensions and fruiting body characters. In this study, we employed a molecular phylogenetic framework with the inclusion of four nuclear loci (ITS, translation elongation factor 1-alpha, actin, and beta-tubulin) to unveil the biodiversity and taxonomy of this understudied important genus of plant pathogens. Phylogenetic inferences based on 150 Californian isolates revealed 15 Cytospora species associated with branch and twig cankers and dieback of almond, apricot, cherry, cottonwood, olive, peach, pistachio, plum, pomegranate, and walnut trees in California. Of the 15 species recovered in this study, 10 are newly described and typified, in addition to one new combination. The pathogenic status of the newly described Cytospora species requires further investigation as most species were associated with severe dieback and decline of diverse and economically important fruit and nut crops in California.

Clinical and epidemiologic studies suggest that the intake of potassium chloride lowers blood pressure. To investigate whether supplemental potassium chloride (96 mmol of microcrystalline potassium chloride a day) reduced the need for antihypertensive medication in hypertensive men on a restricted-sodium diet, we conducted a randomized, placebo-controlled, double-blind clinical trial. A total of 287 men 45 to 68 years of age, 142 given potassium chloride and 145 given placebo, were followed for an average of 2.2 years after the withdrawal of their antihypertensive medication. Men in both groups received instructions on following a low-sodium diet. Overnight urinary sodium excretion fell from 63 mmol per eight hours at base line to an average of 45 mmol per eight hours during follow-up. Participants given supplemental potassium chloride had significantly higher (P less than 0.001) serum potassium levels and urinary potassium excretion (averaging 4.5 mmol per liter and 42.5 mmol per eight hours, respectively) during follow-up than participants given placebo (4.2 mmol per liter and 20.0 mmol per eight hours). Seventy-nine participants in each group required reinstitution of antihypertensive medication according to strict indications defined by the protocol. No significant differences in systolic or diastolic blood pressure were observed between the two groups. During follow-up, systolic and diastolic blood pressure averaged 130.6 and 82.5 mm Hg, respectively, for participants given supplemental potassium, and 132.5 and 83.1 mm Hg for participants given placebo. We conclude that supplemental potassium chloride does not reduce the need for antihypertensive medication in hypertensive men on a restricted-sodium diet.

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 in severe cases can result in tree death soon after orchard establishment. 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 multi-locus phylogenetic analyses of ITS1-5.8S-ITS2 (ITS), and part of the translation elongation factor 1-α (TEF1- α), β-tubulin (TUB2), and glyceraldehyde 3-phosphate dehydrogenase (GPD) gene sequences, which identified 27 species 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 C. destructans, Neoscytalidium dimidiatum and C. californica. Pathogenicity experiments on almond cv. Nonpareil revealed that N. parvum, N. arbuti and N. 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.

Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Prior to this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, sixteen pruning wound treatments were tested using hand-held spray applications, against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81-100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol, T. atroviride SC1 (recommended 2 g/liter) after pruning.

A survey was conducted during 2015 and 2016 in pistachio orchards throughout the San Joaquin Valley of California to investigate the occurrence of canker diseases and identify the pathogens involved. Cankers and dieback symptoms were observed mainly in orchards aged >15 years. Symptoms of canker diseases included brown to dark brown discoloration of vascular tissues, wood necrosis, and branch dieback. In total, 58 fungal isolates were obtained from cankers and identified based on multilocus phylogenetic analyses (internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, β-tubulin, calmodulin, actin 1, and translation elongation factor 1α) representing 11 fungal species: Colletotrichum karstii, Cytospora californica, Cytospora joaquinensis, Cytospora parapistaciae, Cytospora pistaciae, Diaporthe ambigua, Didymella glomerata, Diplodia mutila, Neofusicoccum mediterraneum, Phaeoacremonium canadense, and Schizophyllum commune. Pathogenicity tests conducted in the main pistachio cultivars Kerman, Golden Hills, and Lost Hills using the mycelium-plug method indicated that all fungal species were pathogenic to Pistacia vera. All species tested caused cankers in pistachio branches, although virulence among species varied from high to moderate. Overall, N. mediterraneum and Cytospora spp. were the most widespread and virulent species associated with canker diseases of pistachio in California.

The genus Ceratocystis (Sordariomycetes, Microascales, Ceratocystidaceae) was proposed in 1890 based on C. fimbriata, which was first described as the causal agent of black rot of sweet potato (Ipomoea batatas) in the USA (Halsted 1890). The genus now comprises 39 species (Marin-Felix et al. 2017, Barnes et al. 2018, Liu et al. 2018) and consists of a complex of many cryptic and some host-specialized species (Harrington 2000, Oliveira et al. 2015a) that cause various wilt and canker diseases on a wide range of economically important crops around the world (Kile 1993, Harrington 2013). Hosts impacted by Ceratocystis species include Coffea arabica (coffee), Eucalyptus spp., Ficus carica (fig), Hevea brasiliensis (rubber tree), Mangifera indica (mango), Platanus spp. (sycamore or plane trees), Populus spp. (aspen and other poplars), Prunus spp. (almond and other stone fruits),

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Actionable information must be provided to SOH that will facilitate case management and injury prevention programs and lower costs.