44 MISC. PUBLICATION 168, U. S. DEPT. OF AGRICULTURE 



sometimes on quince. On the market it is found chiefly on apples 

 grown in Washington, Oregon, and California, the varieties most 

 often affected being Jonathan, Grimes Golden, Winesap, Graven- 

 stein, Yellow Newtown, Ben Davis, and Esopus Spitzenburg. 



Control of the disease depends mainly on proper spraying with 

 commercial lime-sulfur or other sulfur sprays. 



(See U2, 59, 65.) 



Quince Rust 



(See Apple-Cedar and Quince Rusts, p. 10.) 



Red Spots 



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 

 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 latter have been ruptured by the growth of the 

 fruit, 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 mis- 

 taken for the effects of San Jose scale, but they can usually be 

 distinguished by their location at lenticels and by the fact that 

 they do not have 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. 



Rhizopus Rot 

 {Rhizopus sp., probably R. nigricans Ehr. ex Fr.) 



Rhizopus rot is seen occasionally on apples and pears on the 

 market, but always on fruit that has been weakened in some way, 

 as, for example, by overmaturity or freezing injury. Affected 

 tissues are soft and watery and have a sour smell. 



Rhizopus is a fungus that occurs widely in nature, It is dis- 

 tributed both by contact and by means of its spores. It can be 

 distinguished from blue mold (Penicillium) and gray mold (Botry- 

 tis) by its dark-colored, coarse mold if it is present and by the 

 gray salt-and-pepper appearance resulting from the young (white) 

 and mature (black) fruiting bodies. 



Rhizopus rot is not likely to occur on pome fruits if they have 

 been handled carefully throughout the processes of picking, pack- 

 ing, and transporting to market. If it becomes established on 

 these fruits, it can be controlled by keeping the fruit temperature 

 below 50° F. 



San Jose Scale Injury 



(Aspidiotus pemiiciosus Comst.) 



The evidence of injury by San Jose scale most commonly 

 noticed on apples is the presence of small reddish areas about % 

 inch in diameter (pi. 2, C). At the center of each of these reddish 



