Penicillium Species Associated with Preharvest Wet Core Rot in South Africa and Their Pathogenicity on Apple.

Symptoms associated with the core region of apple fruits (Malus domestica) can be classified as moldy core (MC), wet core rot (WCR), and dry core rot (DCR). Infections leading to WCR are thought to occur primarily postharvest, although in South Africa preharvest symptoms also have been reported. The first aim of this study was to investigate the causative agent(s) of preharvest WCR by isolating fungi from eight internal positions in asymptomatic, MC, WCR, and DCR fruits.

Bacterial Canker of Sweet Cherry in Oregon-Infection of Horticultural and Natural Wounds, and Resistance of Cultivar and Rootstock Combinations.

This study was done to (i) compare seven types of natural or horticultural injuries and wounds for incidence, severity, and mortality of infection of sweet cherry (Prunus avium) by Pseudomonas syringae pv. syringae; (ii) determine the relative resistance to bacterial canker of 14 cultivar-rootstock combinations; (iii) determine if P. syringae pv.

Description of Cryptosporiopsis kienholzii and species profiles of Neofabraea in major pome fruit growing districts in the Pacific Northwest USA.

The objectives of this study were i) to give a taxonomic description of a fungus phylogenetically related to Neofabraea and assign the name Cryptosporiopsis kienholzii to this fungus, ii) to expand previous Neofabraea species profiles from infected apple and pear fruit collected from major pome fruit production districts in Oregon and Washington, and iii) to determine the sensitivity of Neofabraea alba, Neofabraea malicorticis, Neofabraea perennans, and C. kienholzii to a range of fungicides. A name is given herein to the anamorph of the fungus previously called 'Neofabraea sp.

Methodology for Determining Relationships Between Inoculum Concentration of Botrytis cinerea and Penicillium expansum and Stem End Decay of Pear Fruit.

The objective of this research was to determine quantitative relationships between incidence of stem end decay of pear fruit and inoculum concentration of Botrytis cinerea and Penicillium expansum using dry conidia applied to pear fruit in a settling tower. Five concentrations of conidia were applied to pear fruit, fruit were stored at -1°C for 8 months, and stem end decay was evaluated. In addition, conidia were washed from the surface of inoculated fruit, and DNA was extracted and quantified with real-time polymerase chain reaction (PCR).

Effects of Environmental Factors and Cultural Practices on Bull's Eye Rot of Pear.

Bull's eye rot of pome fruits caused by Neofabraea spp. is characterized by infection occurring in the orchard throughout the growing season whereas rot lesions develop during long-term storage after harvest. Bull's eye rot was observed on pear fruit exposed to natural infection for any of six to nine sequential 1-to-2-week exposure periods during two growing seasons.

Reconstructing the early evolution of Fungi using a six-gene phylogeny.

The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species.

Inoculum Sources of Botrytis cinerea Important to Pear Orchards in Oregon.

Botrytis cinerea was capable of colonizing and persisting in tissue pieces of six common weed species found in pear orchards in Oregon from midsummer until pear harvest in early September. Sporulation occurred on blackberry mummies in orchard perimeters and ranged from 5,700 to 55,000 conidia per mummy at pear harvest. Conidia of B.

Induction of Cankers on Pear Tree Branches by Neofabraea alba and N. perennans, and Fungicide Effects on Conidial Production on Cankers.

Cankers formed on pear branches after inoculations with mycelia of Neofabraea alba or N. perennans, causal agents of bull's eye rot of pear fruit. The highest proportions of successful infections followed inoculations made in fall and winter.

Etiology of Bull's Eye Rot of Pear Caused by Neofabraea spp. in Oregon, Washington, and California.

A collection of Neofabraea isolates from pear fruit grown in Oregon, Washington, and California was screened with species-specific primers in a multiplex polymerase chain reaction (PCR). Neofabraea alba was identified most frequently in samples from Oregon and California, whereas N. perennans was found most frequently in samples from Washington.

Incidence of Postharvest Decay of 'd'Anjou' Pear and Control with a Thiabendazole Drench.

Postharvest decay causes losses to commercial pear industries. The incidence of decay in air and controlled-atmosphere (CA)-stored 'd'Anjou' pear fruit was investigated, and the effect of a prestorage thiabendazole drench on decay in CA-stored fruit was determined. In air storage, bull's-eye rot (31.

Sensitivity of Populations of Botrytis cinerea from Pear-Related Sources to Benzimidazole and Dicarboximide Fungicides.

Botrytis cinerea is responsible for a major portion of postharvest decay in winter pears in the Pacific Northwest. The baseline sensitivity levels (mean EC values) of a wild-type B. cinerea population to thiabendazole and iprodione were 6.

Populations of Botrytis cinerea and Penicillium spp. on Pear Fruit, and in Orchards and Packinghouses, and Their Relationship to Postharvest Decay.

The aims of this study were to examine the sources and population sizes of Botrytis cinerea and Penicillium spp. in 'd'Anjou' pear orchards, packinghouses, and storage, and to determine the relationship between population sizes and postharvest decay. Densities of B.

Disease Incidence-Inoculum Dose Relationships for Botrytis cinerea and Penicillium expansum and Decay of Pear Fruit Using Dry, Airborne Conidia.

The objective of this research was to determine quantitative relationships between incidence of pear fruit decay and inoculum dose of Botrytis cinerea and Penicillium expansum using dry conidia applied to wet or dry pears in a settling tower. On wet fruit, incidence of gray mold fruit rot increased from 0.1 to 83.

Pear Scab: Components of Potential Ascospore Dose and Validation of an Ascospore Maturity Model.

Variables necessary to calculate potential ascospore dose (PAD) for Venturia pirina, the causal agent of pear scab, were measured: area of individual leaves averaged 20.0 cm, number of lesions per infected leaf ranged from 1.8 to 2.

Control of Postharvest Decay in Pear by Four Laboratory-Grown Yeasts and Two Registered Biocontrol Products.

Control of blue mold decay in Bosc pears was studied with the laboratory-grown yeasts Rhodotorula glutinis, Cryptococcus infirmo-miniatus, and two strains of Cryptococcus laurentii, as well as registered biocontrol products Aspire, containing the yeast Candida oleophila, and Bio-Save 11 (now Bio-Save 110), containing the bacterium Pseudomonas syringae. Both thiabendazole (TBZ)-sensitive and TBZ-resistant strains of Penicillium expansum were used. Aspire treatment reduced the average lesion diameter by approximately 65 and 45%, and reduced decay incidence by 27 and 9% with TBZ-resistant and TBZ-sensitive P.