Paecilomyces Rot: A New Apple Disease

Area of Science:

• Mycology
• Plant Pathology
• Food Science

Background:

• Paecilomyces niveus is a food spoilage fungus known to survive thermal processing and produce the mycotoxin patulin in fruit products.
• The ecology and prevalence of P. niveus, particularly its role in fruit spoilage, remain poorly understood, despite its association with soil contamination.

Purpose of the Study:

• To investigate the ecological distribution of P. niveus in orchard soils.
• To determine the pathogenicity of P. niveus on apple fruit and characterize the resulting disease.
• To assess the potential for P. niveus to cause postharvest rot in popular apple varieties.

Main Methods:

• Surveyed orchard soils and culled apple fruit in New York for the presence of P. niveus.
• Inoculated Gala and Golden Delicious apple varieties with P. niveus to test for infection and disease development.
• Observed and measured lesion development and characterized symptoms of the induced disease.

Main Results:

• P. niveus was detected in 34% of sampled New York orchard soils.
• P. niveus successfully infected and caused a novel postharvest disease, termed Paecilomyces rot, in both Gala and Golden Delicious apples.
• Lesions developed on inoculated apples, with sizes reaching ≥43 mm at 22 days post-inoculation, and potential differences in infection rates between apple varieties were noted.

Conclusions:

• Paecilomyces niveus is a common component of New York orchard soil ecosystems.
• P. niveus is capable of causing a distinct postharvest disease in apples, characterized by specific rot symptoms.
• Further research is needed to ascertain if infected fruit contributes to inoculum in processed apple products.