Susceptibility of rosaceous fruits and apple cultivars to postharvest rot by Paecilomyces niveus

Paecilomyces rot of apples is a postharvest disease caused by Paecilomyces niveus, a problematic spoiling agent of fruit juices and derivatives. The fungus produces ascospores that can survive food processing and germinate in finished fruit products. Processing apple fruits infected with Paecilomyces rot can lead to P. niveus contaminated juices. Because the fungus produces the mycotoxin patulin, juice spoilage by P. niveus is an important health hazard. Little is known about the disease biology and control mechanisms of this recently described postharvest disease. Following Koch’s postulates, we determined that a range of previously untested rosaceous fruits and popular apple cultivars are susceptible to Paecilomyces rot infection. We also observed that two closely related food spoiling fungi, Paecilomyces fulvus and Paecilomyces variotti, were unable to infect, cause symptoms in, or reproduce in wounded fruits. Our results highlight the unique abilities of Paecilomyces niveus to infect a variety of fruits, produce patulin, and form highly-resistant spores capable of spoiling normally shelf-stable products.