Jose L. Henriquez

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. N. alba also was identified from tissue of small cankers and pruning stubs on pear trees using PCR. Bulls eye rot pathogens were isolated from fruit of nine different European pear cultivars, Asian pear, and quince. Overall, N. alba was the most prevalent species in 2001 whereas N. perennans was more prevalent in 2002. An undescribed species of Neofabraea was identified in samples from Medford, OR that corresponds to a species previously found by others using molecular methods. This information increases the known geographic distribution of this undescribed species.

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 bulls eye rot of pear fruit. The highest proportions of successful infections followed inoculations made in fall and winter. Cankers induced by N. perennans were larger than those induced by N. alba. Small, superficial cankers were obtained after inoculations with conidia of N. perennans on wounded branches of pear trees. Sporulation of both pathogens on mycelial-induced cankers occurred throughout the year, with the largest amount of conidia produced at the end of summer and during fall. Sporulation on cankers induced by N. perennans spanned at least 2 years. Copper sulfate reduced sporulation on cankers induced by N. alba, while copper sulfate, trifloxystrobin, and ziram applied to sporulating cankers reduced germination of conidia of N. perennans.

Control of grey rot of apple fruits by biologically active natural products

Biorend SC (chitosan), BC-1000 EC (grapefruit extract plus bioflavonoids) and ECO-100 SC (bioflavonoids plus organic acids, citric phytoalexins, fatty acids, glycerides and sugars), respectively, suppressed grey rot of apple caused by B. cinerea by 80.1%, 79.0% and 76.5% when used as post-harvest treatments under controlled conditions. When applied as combined pre- and post-harvest treatments Biorend SC inhibited fruit rot by 49.9 %, while BC-1000 EC and ECO-100 SC were ineffective. None of the products inhibited fruit rot when applied as pre-harvest treatments under controlled conditions or as post-harvest treatments under commercial conditions. The algal polysaccharide ulvan used in post-harvest treatments suppressed grey rot by 56.0% under controlled conditions, but had no inhibitory effect on combined pre- and post-harvest treatments. The inability of products to activate defense mechanisms (chitinase and peroxidase) of fruits was consistent with the unsuccessful control of rot by pre-harvest treatment. The results suggest that the natural products used have potential for use in integrated management of Botrytis rot when applied after harvest.

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

Bulls 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. Bulls 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. Highest infection levels were associated with exposure closest to harvest. Over-tree irrigation and late harvest resulted in higher bulls eye rot incidence than under-tree irrigation and early or mid-season harvest. Fruit were inoculated prior to harvest with Neofabraea perennans to determine the effect of environmental factors on the development of bulls eye rot. The effect of temperature was inconsistent; disease was greatest at 10°C in one year of study but greatest at 30°C in the second year. Bulls eye rot developed independently of wetness durations longer than 0.5 h.

First records of Eocr Onartium muscicola (Basidiomycota, Eocronartiaceae) in Chile on two new hosts

El hongo heterobasidiomycete Eocronartium muscicola es un parasito obligado registrado en alrededor de 21 especies de musgos, principalmente del hemisferio norte. Interactua con los musgos reemplazando el esporofito y de esta forma aprovechando el flujo de agua y nutrientes que va desde el gametofito a traves de tejidos especializados. Este trabajo reporta E. muscicola por primera vez en Chile central y sur con los musgos nativos Eurhynchium corralense y Eurhynchiella acanthophylla en diferentes tipos de formaciones boscosas. Ademas, se comentan los tipos de relaciones entre hongos y briofitas y se discute el estatus taxonomico de los musgos chilenos hospedantes y su relacion con E. muscicola.

Genetic and biological characterization of Macrophomina phaseolina (Tassi) Goid. causing crown and root rot of strawberry

In recent years, crown and root rot of strawberry (Fragaria ×ananassa Duchesne ex Rozier) caused by Macrophomina phaseolina (Tassi) Goid. has affected strawberry production areas worldwide, and in developed countries its emergency has been attributed to the replacement of methyl bromide. The disease was reported in strawberry crop in Chile in 2013, in fields without fumigation. The use of resistant cultivars rises as an alternative to the management of this disease. The objective of this study was to perform a biological and molecular characterization of isolates obtained from two growing regions in Chile and Spain. A total of 35 isolates were characterized for mycelial growth at different temperatures and for chlorate sensitivity. Seven simple sequence repeat loci were used for genetic characterization. Differences were found between Chilean and Spanish isolates in both characterizations. The optimal temperature for mycelial growth was lower in Chilean than in Spanish isolates (30 and 35 °C, respectively). Meanwhile, Chilean isolates were more sensitive to chlorate. In terms of genetic characterization, Polymorphism Information Content (PIC) ranged from 0.38 to 0.85, two main groups were identified, the first group included Spanish isolates and the second group corresponded to Chilean isolates, results were supported by a population structure analysis. This study determined clear differences between two populations of Chilean and Spanish M. phaseolina isolates as causal agent of crown and root rot of strawberry.