WSU Tree Fruit Research & Extension Center

Tree Fruit Market Diseases

Sunday, March 24, 2019

WSU-TFREC/Postharvest Information Network/Tree Fruit Market Diseases/redspots

Aphids, particularly the green apple aphid, sometimes cause red spots or specks on yellow or green varieties of apple. These may be confused with the red spots caused by San Jose scale, but they differ from them in not having a light-colored center.

Similar-appearing red skin spots are particularly common on Yellow Newtown and may occur on other green or yellow apples on the side that has been exposed to the sun. They consist of narrow reddish halos or bands surrounding mechanical injuries or lenticels. If the lenticels have been ruptured by the growth of the fruits, they are more subject to spotting. Exposure to intense sunlight or penetration of the skin by spray materials also seems to stimulate localized reddening on green varieties or on the green portions of red varieties. Such spots are sometimes mistaken for the effects of San Jose scale, but they can usually be distinguished by their location at lenticels and by the absence of white or light-colored centers. The spots have been known to develop extensively just before harvest on apples that up to that time were free of them.

No photos available for this section.

Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us