Three new fungicides (i.e., azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or mixtures 500 mg/liter component) lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive -resistant isolates Penicillium digitatum. In laboratory studies aqueous solutions 9 21 h after inoculation,...

ABSTRACT The causal organism responsible for the recent outbreak of almond and peach anthracnose in California was identified characterized as Colletotrichum acutatum. Isolates C. acutatum from were found to be similar strawberry isolates South Carolina apple based on conidial morphology, temperature relationships, fungicide sensitivity, polymerase chain reaction (PCR) methods using DNA species-specific primers. On almond, blossoms immature or mature fruit affected by disease, causing direct...

In surveys from 2006 to 2014, streptomycin resistance in Erwinia amylovora pear-growing areas California declined very high incidence and 2007 low 2013 2014. The majority of resistant strains were designated as moderately resistant-low (MR-L), almost exclusively found Sacramento County, whereas highly (HR) only recovered Sutter-Yuba San Joaquin counties. Resistance HR was associated with a mutation codon 43 the chromosomal rpsL gene that results change lysine arginine, same originally...

Tomato and pepper plants were grown hydroponically in a greenhouse using phosphate or technical commercial formulations of phosphite as sources phosphorus nutrition to determine the effects on plant development susceptibility Phytophthora root crown rot. Phosphite-treated tomato deficient developed phosphorus-deficiency symptoms. Growth (leaf area leaf, stem, dry weights) that fertilized with was significantly (P < 0.05) reduced compared phosphate-fertilized plants. In capsici-inoculated...

Genetic and biochemical mechanisms of fludioxonil pyrimethanil resistance in isolates Penicillium digitatum were evaluated compared to those characterized other fungi. Resistant naturally occurring packinghouses not associated with crop losses. For the phenylpyrrole fludioxonil, EC50 values 0.02 0.04 microg/ml for sensitive, 0.08 0.65 moderately resistant (MR), > 40 highly (HR) isolates. Two fludioxonil-sensitive also significantly more sensitive unrelated dicarboximide fungicide iprodione,...

In laboratory studies and experimental packingline trials that closely simulated fungicide treatments under commercial conditions, the “reduced-risk” fungicides fenhexamid fludioxonil were highly effective in managing postharvest brown rot gray mold decays of peach, nectarine, plum caused by Monilinia fructicola Botrytis cinerea, respectively. Tebuconazole was more against than mold. Additionally, tebuconazole significantly reduced incidence Rhizopus stolonifer. studies, QoI azoxystrobin not...

Few postharvest treatments are available for managing sour rot of citrus caused by Galactomyces citri-aurantii and they generally not very effective. The demethylation-inhibiting (DMI) triazole fungicides propiconazole cyproconazole were found to be highly effective more efficacious than other DMIs evaluated, such as metconazole tebuconazole, in reducing citrus. Additional studies conducted with a treatment because it has favorable toxicological characteristics food crop registration the...

A new technique, the spiral gradient dilution method, was evaluated for determining 50% effective concentrations (EC 50 values) of fungicides inhibition mycelial growth and conidial germination various fungi. In this an agar medium is plated with a fungicide solution by means plater, which applies in 2.5-log continuous radial concentration gradient. Fungal inoculum then placed along lines across After incubation plates, distinct shapes were observed different fungus-fungicide interactions....

Ganoderma lucidum and G. tsugae are two members of the complex that have had a controversial taxonomic relationship. The authenticity widely distributed wood-rotting species was demonstrated by comparative studies. Specimens isolates both were obtained from several locations in North America. is restricted to hardwoods. Its basidiospores “smooth” walled, characterized narrow, numerous inter-wall pillars, as observed bright-field scanning electron microscopy. Isolates produced chlamydospores...

Three new fungicides, azoxystrobin, fludioxonil, and pyrimethanil, that belong to different chemical classes are highly effective in managing citrus green mold being registered for postharvest use the United States. Recirculating in-line drenches provided a significantly improved efficacy compared with standard low-volume spray applications. To prevent pathogen contamination of drench solutions, two oxidizing disinfectants, sodium hypochlorite hydrogen peroxide/peroxyacetic acid (HPPA) were...

Stem-end rot of harvested avocado fruit commonly occurs wherever the crop is cultivated. Multiple fungal species have been described as causal agents. To determine pathogens stem-end in California, isolations were conducted from symptomatic fruit, and fungi identified by morphological molecular techniques. In 2010 2011, a total 177 isolates recovered 290 collected seven orchards one major growing areas Southern California. The majority was Neofusicoccum luteum (65%), with remainder either...

Anthracnose crown rot of strawberry, caused by Colletotrichum acutatum, is an important disease affecting California nursery and fruit production. Preplant dip treatments transplants with fludioxonil-cyprodinil or azoxystrobin are industry standards for managing the have been used extensively. Following reports reduced efficacy in field, high levels quinone outside inhibitor (QoI) resistance were detected isolates pathogen. Resistance was associated G143A mutation cytochrome b gene, similar...

Phytophthora root rot, caused by several species of Phytophthora, is an important disease citrus in California and other growing regions. For chemical management, mefenoxam potassium phosphite have been available for many years, resistance spp. has reported both compounds. We evaluated the efficacy new Oomycota fungicides ethaboxam, fluopicolide, mandipropamid, oxathiapiprolin, each with a different mode action, against rot field greenhouse studies. Root balls navel orange trees on 'Carrizo...

Phytophthora root rot (PRR), caused by cinnamomi, is the most destructive disease of avocado worldwide. In United States, mefenoxam and phosphonate products are currently only registered fungicides for managing PRR. Four new Oomycota-specific two fungicides, all with different modes action, were evaluated. Seventy-one isolates P. cinnamomi from in California, them collected between 2009 to 2017, tested their vitro sensitivity six fungicides. Baseline ranges mean values (in parentheses)...

Scab of peach and almond is caused by Venturia carpophila but little known regarding the population genetics pathogen, which aids understanding epidemiology disease guiding its management. Isolates (735) V. were sampled from orchards in eastern U.S.A. California, respectively. The aims to determine genetic diversity structure carpophila, compare populations pathogen each host, mating type ratios. Measures gene genotypic indicated greater among as compared pathogen. Mating types consistently...

ABSTRACT In recent years, almond anthracnose has developed into a major problem for the California industry. The identification of causal pathogen as Colletotrichum acutatum was confirmed using species-specific primers and restriction fragment length polymorphisms ribosomal DNA in comparative studies with isolates C. from strawberry gloeosporioides citrus. Two distinct clonal subpopulations among were identified. These two differed their colony appearance (pink versus gray cultures),...

Wood from trunks of Canary Island date palm (Phoenix canariensis) was decayed for 12 weeks with white-rot fungi (Ganoderma colossum, G. zonatum, Phanerochaete chrysosporium, Scytinostroma galactinum, or Trametes versicolor) brown-rot (Wolfiporia cocos, Gloeophyllum trabeum, Fomitopsis pinicola). Using the vermiculite-block assay, caused significantly more weight loss (63%) than (32%). Of fungi, colossum greatest (81%), while S. galactinum least (36%). In contrast, by similar. Chemical...

Isolates of six species Ganoderma in the G. lucidum complex were evaluated for their ability to decay wood Quercus hypoleucoides A. Camus and Abies concolor (Gord. Glend.) Lindl. ex. Hildebr. by using vitro agar block tests. Morphological, ultrastructural, chemical studies decayed used determine extent delignification or simultaneous caused each Ganoderma. All both white fir oak wood; however, less percent weight loss (%WL) occurred than oak. In fir, isolates two undescribed (RLG16161,...

Citrus black spot, caused by Guignardia citricarpa, is a serious fruit spot disease and widely distributed in Asia, southern Africa, South America, but does not occur North America or the Mediterranean region. A nonpathogenic species, G. mangiferae, cosmopolitan with wide host range can colonize citrus leaves saprophytically. Detection identification of spp. on necessary for epidemiological, management, regulatory purposes. In this study, we compared published unpublished polymerase chain...

Comparative field studies on the management of fire blight were conducted in California Asian and Bartlett pear using single-bactericide, mixture, rotation treatments selected compounds. Treatment efficacy was evaluated based natural occurrence disease or after inoculation with Erwinia amylovora. Kasugamycin at 100 mg/liter demonstrated similar higher pre- post-infection activity than industry standards, streptomycin oxytetracycline. Phytotoxicity caused by kasugamycin observed only when...

ABSTRACT Here, we report the complete genome sequence of Xanthomonas arboricola pv. juglandis 417, a copper-resistant strain isolated from blighted walnut fruit ( Juglans regia L. cv. Chandler). The consists single chromosome (5,218 kb).