DISEASES OF PEARS 1047 



oozing, the presence of colonies of bees in an orchard will result 

 in a general infestation. They will not carry the bacteria, how- 

 ever, unless the latter are oozing from infested areas, and the 

 bees cannot inoculate any part of the tree" except the blossom. 

 We believe that these insects do far too much good in cross-pol- 

 linating flowers- to exclude them if we could, and that our efforts 

 at control would better be' directed toward cleaning up sources of 

 infection. Control measures directed toward sucking and biting 

 insects are helpful in reducing the number of new infections. 



As the bacteria are ordinarily unable to enter uninjured tissue, 

 spraying the trees with a fungicide is not effective. None of the 

 numerous blight remedies on the market that we have tried have 

 proved effective in controlling this disease, and -some of them have 

 injured the tree. Growers should not buy such remedies except 

 for experimental purposes. 



When blight infections become general in an orchard, efforts 

 at control by removal of infected areas may be unavailing. An 

 attempt should then be made to stop growth and harden the wobd 

 by ceasing cultivation and even by seeding to a cover crop; in 

 fact, unless one is prepared to fight blight, intensive* cultivation 

 and fertilization may prove to be impracticable. 



Certain varieties, especially Kieffers and Seckel, usually have 

 a shorter susceptible period than do most other trees and are there- 

 fore less likely to become blighted. Cases are known, however, 

 in, which orchards of large Kieffer trees have become badly 

 blighted and in the nursery these varieties blight as badly as any. 

 Grafting susceptible varieties on such stock with the idea of 

 avoiding blight has not given general satisfaction. 



The method of control outlined will not prove successful unless 

 the measures recommended are regularly and systematically car- 

 ried out. The person engaged in it should study the disease in 

 order to be able to recognize all its stages and all the forms in 

 which it may appear, not permitting other work to interfere at 

 any time. For this reason, the general farmer is not prepared 

 to fight fire blight, and in fact there are comparatively few grow- 

 ers prepared to do it. Those who wish to practice good cultural 

 methods and to keep the disease under control would do wisely 

 to employ a person capable of carrying on the work for them. 



