Stone fruit are highly perishable and susceptible to numerous postharvest pathogens. P.
expansum is a well-known pathogen of stone fruit but little is known about other Penicillium
spp. that could potentially cause decay. This study aims to determine pathogenicity profiles
of P. expansum, P. crustosum, P. solitum and P. digitatum on selected nectarine and plum
cultivars, and in part examine the disease cycle within new fruit-Penicillium interactions to
observe the potential of the pathogens to cross-infect. Lesions caused by Penicillium spp.
isolated from the pear and citrus handling chain environments were not different on nectarine.
P. digitatum was the most aggressive species on most nectarines and plums evaluated. Decay
was associated with older fruit (long stored). The highest aggression was observed on
Nectargold, May Glo and African Rose. P. expansum and P. crustosum had the highest
disease incidences and were the second and third most aggressive species respectively. P.
solitum caused small lesions. Its role in the fresh produce market can be negligible.
Scanning electron microscopy confirmed infection and provided new information on the
growth and reproduction of P. expansum, P. crustosum and P. digitatum on infected
nectarine, pear and lemon. Pear and lemon can serve as cross-infection sources for stone fruit
in the fresh produce chain. To our knowledge this is the most complete description of disease caused by P. digitatum, P. crustosum and P. solitum on nectarine and plum. Rapid decay
caused by P. digitatum highlighted the potential of the species to contribute to losses in the
stone fruit industry. Future research should investigate the presence and impact of P.
digitatum in the stone fruit supply chain. The role of fruit maturity in fruit-Penicillium
interactions requires further investigation.