American Pomological Society. 177 



however, made some preliminary experiments which seem to give some 

 indication of the methods to be used in combatting it. The first and 

 most difficult demand of the grower is that we cure the diseased plant. 

 In most cases this is impossible or the value of the plant does not warrant 

 the effort required to save it. But in this case the saving of a tree just 

 coming into bearing seemed worth the while. I, therefore, treated can- 

 kered trees in various ways. I will not burden you with unsuccessful or 

 doubtful remedies. The treatment, which at present appears most suc- 

 cessful, is to clean out the canker, i. e., remove with a sharp knife all 

 diseased tissue, swab out the wound with a (one-fifth per cent) solution 

 of corrosive sublimate or a three per cent solution of copper sulphate, and 

 when dry paint over thoroughly with some heavy paint. The painting 

 should be repeated later in the season. This sort of treatment was given 

 in the spring or early summer, so that wounds would have time to heal 

 well, which they did in most cases. A sharp watch should be kept for 

 the appearance of these cankers, and they should be promptly cut out 

 and treated. 



It has long been known that highly fertilized and cultivated pear 

 orchards suffered most from attacks of the twig blight, and it is not sur- 

 prising that the same seems to be true of the apple trees. Although 

 my observations on this point are limited, they seem sufficient to make it 

 a safe statement that cultivation and fertilization greatly increases the sus- 

 ceptibility of the apple tree to this disease. This seems to have been shown 

 in the case of one orchard visited. One end of the orchard had not been 

 cultivated for several years, while the remainder had been cultivated every 

 year since setting until the last two seasons. The untilled portion showed 

 a very low percent of affected trees, while the cultivated trees had al- 

 most completely gone out. 



My observations seem to show that there is also considerable differ- 

 ence in resistance of different varieties to the disease. Of those varie- 

 ties that have come under my notice, only one seems to be entirely im- 

 mune to attacks of the organism. In an orchard of some 200 trees all 

 have gone out except seven Wolf Rivers, which show not a single canker 

 and are strong and thrifty. A provisional arrangement of the varieties 

 observed according to their resistance ability may be said to be: Wolf 

 River, Talman Sweets, Pewaukee, Red Astrachans, Tetofsky, Grimes 

 Golden, Winesap, Fameuse. The more susceptible varieties seem to be : 

 Baldwins, Ben Davis, Mann, Hubartson, Fall Pippin, Stark, Greenings. 



Observations made in several orchards where top grafting has been 

 practiced indicate that desirable varieties especially susceptible to the 

 canker may be grown by top grafting on resistant stocks. Talman Sweets 



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