MENACE TO ORCHARDING. 207 



left covered with a heavy coat of asphaltum. 



Now is the time to cover all these exposed cankered surfaces, to 

 prevent the scattering of spores which are formed during July, 

 August and September. This same covering will also guari against 

 the scattering of the spores which are formed beneath the surface 

 next spring. 



The third class of trees are those which are so badly diseased 

 that they no longer bear. For this class there is no remedy but to 

 ■cut down and cast into the fire. 



The Question of Disinfectants and coverings for wounds, is a 

 very important one in orcharding. The ravages of blister canker dur- 

 ing the last ten years has especially emphasized the need of reliable 

 disinfectants and covers for pruning and other wounds. Orchard 

 sanitation is an absolute prerequisite to success in orcharding today. 

 Under present conditions of the prevalence of disease two operations 

 are necessary in dresing tree wounds. The wound must be sterilized 

 to destroy any fungi or bacteria which may be present, and it must 

 be covered to prevent infection through the later entrance of fungous 

 or bacteria. 



The sterilization of the wound may be accomplished by applying 

 some anticeptic or germ killing material directly to the wounded sur- 

 face by means of a brush or a small hand spray. The most satis- 

 factory disinfectants are carbolinsum, corrosive sublimate or carbolic 

 acid, though gasoline, kerosene, copper sulphate solution, formalde- 

 hyde, etc., may be used. Wlien the cover is applied immediately the 

 disinfectant may be mixed with it and one application be made to 

 answer both purposes. 



Where there is evidence of disease in the orchard all pruning 

 tools should be disinfected after finishing each tree, or after cutting 

 through any diseased limb, by dipping in some one of the before 

 mentioned materials or by swabbing off with them. 



The cover must consist of such materials that the wound will 

 not be allowed to dry out. They must be impervious to water and 

 exclude air. They must be adhesive and not be so affected by changes 

 in temperature that they will erack or fall away from the wound. In 

 order to secure a good covering the material must be of such a 

 consistency that it will spread easily and evenly, and must be cheap 

 enough not to be prohibitive. 



White lead and linseed oil, Venetian red and linseed oil or 

 chrome yellow and linseed oil make good coverings for small prun- 

 ing wounds, but are useless for coverings for large wounds for if 

 applied in a thin coat the Wound checks, and if applied in heavy 

 coats the paint blisters and peels off. 



Tars of various sources are often used as coverings for tree 

 wounds. 



Coal tar, which is a byproduct of coal oil refineries and which 

 contains gasoline or naptha or both is said to be injurious to the 



