Tree Fruit Research & Extension Center

Cullage Assessment & Education

Quick Identification Guide to Apple Postharvest Defects & Disorders

Postharvest Diseases

The Diseases section of the card set includes all the major fungal diseases found in stored Washington apples. This section also includes a Symptom Comparison Table to help. At a later date more cards may be developed for this section which would include any newly discovered pathogens. For ordering information visit the Order Information section of the Introduction. The cards shown on this site are slightly modified to accomodate web formatting. Figures may appear fragmented in some browsers. Please report viewing problems here. Any reproduction of the card images or content without permission is in violation of WSU Copyright policies.

Postscript:  Since the publication of this card set, a new fungal disease was discovered and identified, Phacidiopycnis washingtonensis, AKA Speck rot. This fungas has become a serious quarantine pest for some export markets, such as China. Dr. YK Kim and Dr. CL Xiao, both formerly of WSU, fully describe this disease in their paper found here. Although not found in the printed card set, we have included a description of this disease with the other fungal disease below.



DISEASES: Gray Mold  

Gray mold symptoms

Gray mold (Botrytis cinerea) is a common post-harvest disease on apples worldwide. This fungus has the ability to spread from decayed fruit to surrounding healthy fruit through fruit-to-fruit contact during storage. Because of this, significant losses as high as 20-60% are not uncommon after an extended period of storage, particularly on fruit that were not treated with fungicides prior to storage.

Gray mold symptoms
Gray mold symptoms

Figure 1: Gray mold originating from infection at stem or stem bowl; gray spore masses may be visible at the diseased area under high humidity.
Figure 2: Gray mold commonly originating from infection of wounds on the fruit; decayed area brown, spongy to firm; decayed tissue may become soft in very advanced stage.
Figure 3: Gray mold originating from infection of the calyx of a Red Delicious; white to gray mycelium and gray spores may cover the decayed area under high humidity conditions.




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