Apple growers need to spray fungicides to control destructive apple diseases that are present on leaves and fruit. Paecilomyces niveus is a fungus found in soil that can survive in orchard soils and can infect fruit through wounds.
Researchers Megan N. Biango-Daniels and Kathie T. Hodge, of the section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science at Cornell University in Ithaca, NY, conducted research to observe similarities and differences between P. niveus and other common fungi that cause post-harvest apple diseases. They demonstrated that apples can be infected through wounds on the fruit. Paecilomyces rot looks similar to other apple diseases, such as black rot, bitter rot and bull’s-eye rot.
External symptoms of Paecilomyces rot include brown, circular, concentrically-ringed lesions, with an internal rot that is firm and cone-shaped. P. niveus has been known to be present in soils, and Biango-Daniels and Hodge’s work showed that it was present in some New York orchard soils. Infected fruit may be important because P. niveus makes patulin, a mycotoxin, and spores of this fungus are able to survive high temperatures. This mold is already known as an important food spoilage fungus. Patulin is also made by blue mold rot in apples and can cause acute toxicity symptoms that include convulsions; sub-acute toxicity can include gastrointestinal disorders, and there are concerns that it is carcinogenic.
Growers know that fruit that falls from the tree to the ground can be infected by bacteria and fungi through wounds and soil contact. This work points out another thing to consider: that it could be possible for apples infected with this disease to cause food spoilage in finished products. The researchers say that more studies are needed to understand this fungus on apples, and they hope that now that it’s been described, growers will keep an eye out for it and consider the consequences that might arise from using damaged fallen fruit that has contacted the soil for processing.