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



spots on the fruit than are common for apple scab and occurs more 

 frequently on the twigs than apple scab. On Seckel and possibly 

 other varieties very small scab spots that may be mistaken for 

 other blemishes if not carefully examined sometimes occur. 



Pear scab is an important disease in many of the commercial- 

 pear-growing sections. It can be controlled by the treatment rec- 

 ommended for apple scab (p. 47) . 



(See 59, 65.) 



Scald 

 common form 



A brown to black discoloration of the skin of Bartlett, Bosc, 

 and some other commercial varieties of pears is known as scald. 

 The disease is apparently much less common on the market than 

 apple scald, and it is not understood so well. Although there is no 

 definite proof that it is caused in the same way as apple scald 

 (p. 47), certain investigations have shown that, like apple scald, 

 it is worse on immature than on mature fruit and is most likely 

 to occur when ventilation is poor. In early stages the disease is 

 entirely superficial, but it progresses rapidly into the flesh at 

 moderate or high temperatures. In late stages the skin becomes 

 weakened and sloughs off readily, so that scald is very likely to 

 be followed by blue mold rot and other decays. 



The taste and odor of affected fruit are characteristically dis- 

 agreeable and sickening even before discoloration appears. The 

 ordinary form of scald has been found to develop on pears of the 

 Bartlett variety in 30 to 35 days at 43° F. and in 70 to 80 days at 

 36°, and it generally does not develop at all at 31° during the or- 

 dinary storage period for this variety. On other commercial varie- 

 ties stored at 32° scald does not usually develop to any serious 

 extent until near the end of their maximum storage period. Oiled 

 paper used as for apple scald has not given control of this common 

 form on pears. 



(See 86, 103.) 



ANJOU SCALD 



On Anjou pears scald causes a brown or dark discoloration 

 (pi. 14, D), which detracts materially from the appearance of the 

 fruit, but it is not accompanied by sloughing of the skin or by 

 unpleasant odors as in the common form and does not impair 

 eating quality. The condition occurs (1) on both washed and un- 

 washed fruit, (2) on precooled fruit and on fruit that has not 

 been precooled, and (3) on fruit held constantly at 32° F., as well 

 as on fruit held for various lengths of time at other temperatures. 



The disease may be controlled by wrapping in oiled paper, so 

 that in this respect Anjou scald seems to be similar to apple scald. 



(See 5k, 56.) 



Side Rot 



Side rot, caused by Phialophora malorum, occurs on pears grown 

 in the Pacific Northwest, and at times it has been serious. The 

 decay spots are relatively small and dark brown to black (pi. 13, F). 

 They never have pale centers like those of bull's-eye rot on pear. 

 (See also Apples, Side Rot, p. 48.) 



