Inoculum sources and infection pathways of pathogens causing stem‐end rots of ‘Hass’ avocado(PerseaAmericana)

Abstract

Species of Colletotrichum, Botryosphaeria, and Phomopsis causing postharvest rots in avocado (Persea americana Miller) fruits are present in the living and dead branches and twigs of avocado trees, and in the living pedicels. They dominate the fungal population within the extra-cambial tissues but are less common within the xylem elements. There is no evidence that invasion of these tissues is pathogenic. With the possible exception of C. gloeosporioides they appear to be discontinuously present and are more properly termed phellophytes rather than endophytes. There was a higher incidence of stem-end rots than of body rots in untreated (control) 'Hass' avocados in New Zealand experiments and most of these stem-end rots were associated with B. parva and Phomopsis spp. A high proportion of stem-end infections appeared to be initiated during harvesting. Picking the fruit by snapping the pedicels instead of clipping, as in commercial practice, resulted in an unusually high level of stem-end rots caused by C. acutatum. Frequently sterilising the clippers used to harvest the fruits reduced the incidence of stem-end infections, in particular those caused by B. parva, indicating that contamination of the clippers is an important source of infection. It is suggested that this contamination is probably present as fragments of infected extracambial tissue.

Characterisation and pathogenicity of fungal species associated with branch cankers and stem-end rot of avocado in Italy

“…Recently, Twizeyimana et al (2013) showed that the pathogens causing cankers may be a source of inoculum for stem-end rot. Conversely, fungal species associated with stem-end rot could cause branch cankers (Hartill and Everett 2002;Menge and Ploetz 2003). In Mediterranean environments, pathogens belonging to the fungal groups mentioned previously are reported to cause diseases on a range of woody plants species and their fruit.…”

“…Frost-or mechanical injuries such as pruning wounds may allow these canker-causing pathogens access to initiate infection. Various species of the Botryosphaeriaceae cause stem-end rot of avocado (Hartill and Everett 2002;Menge and Ploetz 2003). Stem-end rot starts as a dark-brown to black rot at the stem-end of the fruit with darkening of the internal vascular bundles.…”

“…Simmonds) and Pestalotiopsis spp. (Hartill and Everett 2002;Valencia et al 2011). Recently, Twizeyimana et al (2013) showed that the pathogens causing cankers may be a source of inoculum for stem-end rot.…”

Isolation and Pathogenicity Evaluation of Postharvest Fungal of Some Fruits in Cameroon

“…Fruits play an important role in socioeconomic. Surveys conducted by Hartill and Everett (2002), Everett et al (2007) showed that anthracnose, stem rot, galls, fruit spot and fruit rot were the most important fungal diseases. The incidence of these diseases can be up to 90% in areas with high relative humidity (COLEACP, 2008).…”

Exotic plant disease threats to the New Zealand avocado industry and climatic suitability: a review

“…These pathogens have a wide host range and may have originated from infected host material already present in New Zealand or from infected avocado plant material imported in 1907, 1917 and 1940. Most fungi that infect fruit to cause rots will also asymptomatically infect vegetative tissue (Everett et al 1999;Hartill & Everett 2002;Everett et al 2003). The first record of an avocado fruit rot was of C. gloeosporioides Pathogens 1 (Brien 1939), and the first record of a root disease was of Phytophthora cinnamomi (Zentmeyer 1965), then the vascular wilt pathogen V. dahliae (Fletcher 1976).…”