Penicillium: Species causing blue mold on stored apple fruits

Blue mold, caused by the fungal species of genus Penicillium, is one of the most significant post harvest apple diseases. It is estimated that apple blue mold causes multimillion-dollar losses annually. It can affect any apple variety, due to mechanical damage, inadequate protection or storage conditions. Various Penicillium species can cause apple blue mold, but the most significant is Penicillium expansum. Besides economic losses, Penicillium species cause a threat to human health, due to mycotoxin production. To prevent the apple blue mold, the application of preventive measures is necessary, such as careful handling of fruits during harvest, and maintaining hygienic conditions in the storage. Most of the current preharvest fungicides are applied days before harvest and may not be effective in combating this disease, since Penicillium infections usually occur after the harvest. Therefore, post harvest fungicide applications remain the most effective chemical way to control blue mold. In addition to chemical protection, efforts are made to provide efficient biological solutions for the control of this disease. The incidence of apple blue mold is significantly reduced since controlled atmosphere storages are in use, but it still remains the most important post harvest disease of apple fruits.