MAEKET DISEASES OF APPLES, PEAKS, QUIN-QES 57 



Investigations made in England have shown that the ripening of 

 apples can be retarded without ill effects on the fruit by reducing 

 the amount of oxygen in the air and increasing the amount of carbon 

 dioxide. These results were obtained, however, only when the pro- 

 portions of oxygen and carbon dioxide in the air of the storage room 

 were kept constant at the figure that had been found most satisfac- 

 tory (carbon dioxide 10 to 15 percent and oxygen about 10 percent) 

 and the temperature was maintained at approximately 40° F. If 

 the carbon clioxide was allowed to increase beyond 10 percent an 

 internal browning was produced which these investigators called 

 brown heart. 



Fruits that have deteriorated badly because of faulty gas storage 

 are usuallv discolored inside and out and have a fermented odor and 

 taste. (4, il^, l^S, 138, HI, 228.) 



SOOTY BLOTCH 



(See Apples, Spray Injury, p. 46) 



SPRAY INJURY 



(See Apples, Sooty Blotch, p. 45) 



STIGMONOSE 



(See Apples, Stigmonose, p. 47, and pi. 14, C, D) 



QUINCES 

 BLACK ROT 



(See Apples, Black Rot, p. 10) 

 BLACK SPOT 



{Fatraea maculata (Lev.) Atk.) 



Black spot appears as black, circular, slightly sunken spots vary- 

 ing in diameter from about one sixteenth to three eighths of an inch. 

 They are usually surrounded by a red ring, and in late stages may 

 show cracking as in pear scab (pi. 16, E). They may occur on any 

 part of the fruit. 



The disease does not develop or spread in storage or transit and is 

 not commonly followed by rot of any kind. It occurs on both pears 

 and qfuinces and is most common in regions east of the Mississippi 

 River. It has not been reported on fruit from California or the 

 Northwest. 



The pathogene causes a spotting of the leaves of pear and quince 

 that is occasionally quite serious, especially on nursery stock. 



Commercial control of the disease can be obtained by spraying 

 with lime-sulphur 1 to 50, to which iron sulphate has been added, as 

 a sticker, at the rate of 3 pounds to 50 gallons. The first application 

 should be made soon after the first leaves appear, followed at in- 

 tervals of about 3 weeks by 3 or 4 other applications. (5, 61, 100, 

 1U,1S8.) 



