Important postharvest pathogens of pear and their dynamics in plant residues in Dutch pear orchards

Samenvatting

Postharvest diseases of pear cause significant losses. Epidemiological knowledge of these diseases is limited. Packinghouse surveys of postharvest diseases on stored pear fruit were conducted from 2012 to 2018. TaqMan PCR assays were developed for quantification of Neofabraea alba and Cadophora luteo-olivacea in environmental samples from orchards. Various host tissues, dead weeds and grasses, soil and applied composts were collected in 10 pear orchards. The temporal dynamics of pathogens was followed in four pear orchards. The most important pathogens in terms of incidence and severity of stored pears were Cadophora spp., causing side rot, and Fibulorhizoctonia psychrophila, causing lenticel spot. These pathogens, as well as Neofabraea spp., infect fruits during the growing season and remain quiescent until disease symptoms occur after several months in storage. Neofabraea alba was detected in 58% of environmental samples from pear orchards. Cadophora luteo-olivacea was detected in 95% of environmental samples. In these orchards, N. alba and C. luteo-olivacea were found in highest concentrations in pear leaf litter and in dead weeds. Substrate colonization varied considerably between orchards. Knowledge on population dynamics is essential for the development of preventative measures to reduce risks of fruit infections during the growing season.