Tree Fruit Research & Extension Center

Cullage Assessment & Education

Quick Identification Guide to Apple Postharvest Defects & Disorders Cards

Fruit Finish

The Fruit Finish section of the card set includes sun and heat induced disorders found in Washington apples. This includes sunburn browning, sunburn necrosis and photo-oxidative sunburn (previously refered to as Type III sunburn). At a later date more cards may be developed for this section which would include any emerging or reclassified disorders. 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.

 

 

FRUIT FINISH: Photo-oxidative Sunburn   

Photo-oxidative sunburn

Apples that are suddenly exposed to sunlight after growing in shade, as would occur with hand thinning or late-season pruning, may develop photo-oxidative sunburn. Unlike sunburn browning or sunburn necrosis, this is neither surface temperature, nor UV-B dependent. In addition to happening on the tree, it can also occur after harvest if apple bins are left sitting out in the sun in the field, on a truck, or at the loading dock.

Appearance of photo-oxidative sunburn varies by severity. In general, it appears first as whitened peel (i.e., photo-bleaching) with browning appearing later.

Figure 1: Photo-oxidative sunburn on Granny Smith with slight browning.

Figure 2: Photo-oxidative sunburn on Red Delicious with darker browning.

Photo-oxidative sunburn

 

 

 

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