Postharvest decay of nectarine and plum caused by Penicillium spp.

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 aggressiveness 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 and 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. [GRAPHICS] .