Effect of Bloom Sprays on Alternaria Rot in California Mandarins and Fungicide Efficacy Against .

This study aimed to provide new insights into the management of Alternaria rot and Colletotrichum dieback in mandarins. Field trials were conducted to evaluate the impact of bloom sprays on latent infections, disease progression, and the influence of bloom inoculations on disease development. Detached citrus leaves were used to assess the efficacy of commercial fungicides in reducing infections by spp.

Ochratoxin A Contamination of California Pistachios and Identification of Causal Agents.

Ochratoxin A (OTA) is a potent mycotoxin produced by and spp., which contaminates many crops, including pistachios. Pistachios contaminated with OTA may be subjected to border rejections resulting in significant economic losses to the United States agricultural revenues.

Reassessing the Etiology of Aspergillus Vine Canker and Summer Bunch Rot of Table Grapes in California.

Fungal taxonomy is in constant flux, and the advent of reliable DNA barcodes has enabled the enhancement of plant pathogen identification accuracy. In California, Aspergillus vine canker (AVC) and summer bunch rot (SBR) are economically important diseases that affect the wood and fruit of grapevines, respectively, and their causal agents are primarily species of black aspergilli ( section ). During the last decade, the taxonomy of this fungal group has been rearranged several times using morphological, physiological, and genetic analyses, which resulted in the incorporation of multiple cryptic species that are difficult to distinguish.

Survey on Latent Infection of Canker-Causing Pathogens in Budwood and Young Trees from Almond and Prune Nurseries in California.

Almond band canker and prune Cytospora canker have become more severe in the last decade, especially in young orchards, in California. To test our hypothesis that young trees from nurseries could carry the canker-causing pathogens at latency phase to new orchards through transplanting, a multiyear survey on latent infection of canker-causing pathogens of budwood and young trees of almond and prune nurseries in California was conducted. A total of more than 1,730 samples including shoots of rootstocks and scions and grafting union cuttings were collected from 11 nurseries.

Sporulation and Dispersal of the Biological Control Agent AF36 Under Field Conditions.

Aflatoxins are carcinogens produced by the fungi and that contaminate pistachio crops. International markets reject pistachio when aflatoxins exceed permitted maximum levels. Releasing the atoxigenic strain AF36 of is the leading aflatoxin pre-harvest control method.

Prevalence, Identity, Pathogenicity, and Infection Dynamics of Botryosphaeriaceae Causing Avocado Branch Canker in California.

Botryosphaeria branch canker and dieback of avocado ( Mill.) has expanded in avocado-growing areas in recent years. Twenty-one avocado groves in the major producing regions of California were surveyed in 2018 and 2019.

Pistachio Male Inflorescences as an Alternative Substrate for the Application of Atoxigenic Strains of .

Aflatoxins are carcinogens mainly produced by and in susceptible crops, including pistachio. The primary inoculum sources of these pathogens are plant debris in the orchard soils. In Californian fields, one approach to controlling aflatoxin contamination is based on releasing the atoxigenic strain of AF36 in inoculated (coated) sorghum grains (AF36 Prevail).

Frequency of Genotypes Resistant to SDHI Fungicides in California Pistachio Orchards Determined by Real-Time PCR.

Real-time PCR methods were developed to quantify the frequency of SDHC-H134R and SDHB-H277Y mutants associated with succinate dehydrogenase inhibitors (SDHI) resistance in populations from pistachio. The linearity of the standard curves demonstrated the applicability in the quantification of the assays. The accuracy and reliability of the qPCR protocols to determine the frequency of mutants in real samples were corroborated.

spp. Associated with Dieback Disease in China.

A rare plant species of the family, is considered among the top ten Chinese medicinal herbs for its polysaccharide. Since 2021, when the dieback disease of was first reported in Yueqing City, Zhejiang Province, China, isolates (number = 152) were obtained from 70 plants in commercial greenhouses. The disease incidence ranged from 40% to 60% in the surveyed areas.

Effects of Cultivar Susceptibility, Branch Age, and Temperature on Infection by Botryosphaeriaceae and Fungi on English Walnut ().

Botryosphaeriaceae and fungi have been described as the main causal agents of branch dieback and shoot blight of English walnut ( L.). To date, the effects of biotic and abiotic factors on disease development on this host are still poorly understood.

Characterization, pathogenicity, and fungicide sensitivity of Alternaria isolates associated with preharvest fruit drop in California citrus.

Alternaria rot has been recently described as an emerging fungal disease of citrus causing significant damage in California groves. A survey was conducted to determine latent infections on fruits, twigs, and leaves and investigate their seasonal patterns during 2019 and 2020. On fruits, latent infections were more associated with the stem end than with the stylar end, except during spring when a significantly high percentage of flowers (86%) had latent infections.

Identification and characterization of Colletotrichum species associated with anthracnose on persimmon in Brazil.

Persimmon (Diospyros kaki) anthracnose is a major threat in production areas worldwide. Most of the studies are focused on Colletotrichum horii, but other species have been reported as well. The association of distinct Colletotrichum species present in Brazilian persimmon production regions as well as their host ranges are yet elusive.

Characterization of Isolates Causing Colletotrichum Dieback of Citrus in California.

Dieback caused by spp. is an emerging disease in California citrus groves. A large-scale survey with emphasis on seasonal variations of latent infections was conducted throughout citrus orchards in Fresno, Kern, and Tulare counties in 2019 and 2020.

Update of pistachio leaf spot caused by Septoria pistaciarum in light of new taxonomic advances in Italy.

Septoria leaf spot is one the most widespread disease affecting pistachio (Pistacia vera) in countries of the Mediterranean region. Traditionally, three species have been associated with pistachio, including Septoria pistaciae, Septoria pistaciarum and S. pistacina.

Etiology of Botryosphaeria Panicle and Shoot Blight of Pistachio () Caused by Botryosphaeriaceae in Italy.

Pistachio () is an important crop in Italy, traditionally cultivated in Sicily (southern Italy) for several decades now. In recent years, new orchards have been planted in new areas of the island. Field surveys conducted in 2019 revealed the presence of symptomatic trees showing shoot dieback, cankers, fruit spots, and leaf lesions.

Resistance to and in Almond Advanced Selections and Cultivars and Its Interaction with the Aflatoxin Biocontrol Strategy.

Aflatoxin contamination of almond kernels, caused by and , is a severe concern for growers because of its high toxicity. In California, the global leader of almond production, aflatoxin can be managed by applying the biological control strain AF36 of and selecting resistant cultivars. Here, we classified the almond genotypes by K-Means cluster analysis into three groups (susceptible [S], moderately susceptible [MS], or resistant [R]) based on aflatoxin content of inoculated kernels.

Baseline Sensitivity of and to Natamycin and Control of Alternaria Rot on Stored Mandarin Fruit.

Alternaria rot caused by and is one of the major postharvest diseases on mandarin fruit in California. In this study, natamycin, a newly registered biofungicide, was evaluated for its potential as a postharvest treatment to control Alternaria rot on mandarin fruit. The baseline sensitivities of and to natamycin were determined.

Limited Evidence for Accumulation of Latent Infections of Canker-Causing Pathogens in Shoots of Stone Fruit and Nut Crops in California.

Prevalence of latent infections of the canker-causing fungi and species of , , , , and in young shoots of almond, prune, and walnut trees in California was studied to test the hypotheses that latent infections accumulate from current-season shoots to 1-year-old shoots in the orchard and there are distinct associations among pathogen taxa present as latent infections in the same shoot. Samples of newly emerged and 1-year-old shoots were periodically collected in each almond, prune, and walnut orchard for two growing seasons. A real-time quantitative PCR assay was used to quantify latent infection with three parameters: incidence, molecular severity, and latent infection index.

Phylogenetic, Morphological, and Pathogenic Characterization of Species Associated With Fruit Rot of Mandarin in California.

Alternaria rot caused by species is one of the major postharvest diseases of mandarin fruit in California. The aims of this study were to identify these species via phylogenetic analyses and morphological characteristics and test their pathogenicity on mandarin. Decayed mandarin fruits exhibiting Alternaria rot symptoms were collected from three citrus fruit packinghouses in the Central Valley of California.

Effect of Cultivar Resistance and Soil Management on Spatial-Temporal Development of Wilt of Olive: A Long-Term Study.

wilt, caused by , challenges olive cultivation and an Integrated Disease Management (IDM) approach is the best-suited tool to combat it. Since 1998, an IDM strategy in an orchard (called Granon, Spain) of the susceptible cv. Picual was conducted by increasing planting density with moderately resistant cv.

Quantification of the Aflatoxin Biocontrol Strain AF36 in Soil and in Nuts and Leaves of Pistachio by Real-Time PCR.

The species and are commonly found in the soils of nut-growing areas in California. Several isolates can produce aflatoxins that occasionally contaminate nut kernels, conditioning their sale. Strain AF36 of , which does not produce aflatoxins, is registered as a biocontrol agent for use in almond, pistachio, and fig crops in California.

Cross-Resistance Among Demethylation Inhibitor Fungicides With Brazilian Isolates as a Foundation to Discuss Brown Rot Control in Stone Fruit.

Despite the resistance problems in , demethylation inhibitor fungicides (DMIs) are still effective for the disease management of brown rot in commercial stone fruit orchards in Brazil. This study aims to investigate the sensitivity of isolates and efficiency of DMIs to reduce brown rot. A set of 93 isolates collected from Brazilian commercial orchards were tested for their sensitivities to tebuconazole, propiconazole, prothioconazole, and myclobutanil.

Further Investigation on Limb Dieback of Fig () Caused by in California.

Fig limb dieback is a cosmopolitan disease caused by (Botryosphaeriaceae), characterized by branch and shoot cankers, discoloration of woody tissues, and dieback. The present study investigated the etiology of the disease in California that seems to have become prevalent among fig orchards in the last several years. During orchard surveys in Fresno, Kern, and Madera Counties over 3 years, we isolated consistently and evaluated the pathogenicity of under laboratory and field conditions.