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: Symptom Comparison Table  

Symptoms Blue Mold Gray Mold Sphaeropsis Rot Mucor Rot
Texture Soft, watery; lesion with a sharp margin; decayed tissue completely separable from the healthy tissue, leaving it like a “bowl” Spongy or firm; decayed tissue not separable from the healthy tissue Firm Very soft; juicy
Decay Color Light tan to dark brown Light brown to dark brown Brown to dark brown, advanced decay area may turn black Light brown to brown
Signs of Pathogen White mycelia and blue or blue-green spore masses; sporulation often starts at the infection sites (wounds) Fluffy white to gray mycelia; sporulation under high humidity; gray to brown spore masses; black sclerotia may form White mycelia under high humidity; advanced stage: pycnidia may form on decayed fruit Gray mycelium with dark sporangia
Internal Color Brown Light brown to brown Brown; decay advances along the vascular tissue; decay turning it brown Light brown to brown
Odor Earthy, musty Generally not detectable Strong distinct “bandagelike” odor Sweet



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