Citrus fruit are exposed to numerous postharvest pathogens throughout
the fresh produce supply chain. Well-known postharvest citrus fruit
pathogens are Penicillium digitatum and P. italicum. Lesser-known
pathogens include P. crustosum and P. expansum. This study examined
pathogenicity and aggressiveness of Penicillium spp. present in fresh
fruit supply chains on various Citrus spp. and cultivars. The impact of
different inoculation methods and storage conditions on decay were
also assessed. P. digitatum and P. italicum were the most aggressive
Penicillium spp. on citrus but aggressiveness varied significantly over
the evaluated citrus range. Decay and tissue-response lesions caused by P. crustosum were observed on ‘Nules Clementine’, ‘Nova’, ‘Owari
Satsuma’, ‘Delta Valencia’, ‘Cambria Navel’, ‘Eureka’ seeded, and
‘Star Ruby’ for the first time. Likewise, these lesions caused by P.
expansum were noted on Nules Clementine, Owari Satsuma, Delta
Valencia, ‘Midknight Valencia’, and Eureka seeded for the first time.
Tissue-response lesions affect fruit quality and some Penicillium spp.
sporulated from the lesions, causing the inoculated species to complete
their life cycle. New citrus–Penicillium spp. interactions were observed
and the importance of monitoring inoculum loads of pathogens and
nonhost pathogens were highlighted.