68 



Canker on Apple and Pear Trees. 



by the Bacillus amylovorus in America. The treatment which 

 has been found successful in arresting this disease in trans- 

 atlantic orchards may prove equally successful in this 

 country. It is simple, consisting merely in cutting out and 

 burning every particle of infected wood before the sap begins 

 to rise. The infected centres may, however, be cut away at 

 all times of the year. American experts advise that a 

 careful inspection should be made of all apple and pear trees 

 two or three times during the summer. It takes two or three 

 years for the disease to become a serious epidemic; but the 

 early removal of the first cases will prevent this development, 

 and will, at the same time, save much labour later, as well 

 as many valuable trees.* 



Specimens of diseased apple branches were sent to the 

 Board of Agriculture from Victoria, British Columbia, in 

 February last, by Mr. Palmer, Inspector of Fruit Pests, who 

 found that while the disease affecting them was much the 

 same as that described as canker, or Nectria ditissima, in this 

 Journal for December, 1895, it differed in certain respects, 

 although its effects on the trees were similar. The branches 

 sent were from a Rhode Island Greening- apple tree, the whole 

 of which is affected more or less, and will, it is thought, 

 succumb during the present year. Mr. Palmer writes : -' It 

 seems to me that you may have in England other forms of 

 canker besides Nectria ditissima , one ot w T hich may be iden- 

 tical with the specimens now sent." An examination of these 

 indicated that the cause of the disorder was not Nectria. 

 ditissima, though, as Mr. Palmer said, there was consider- 

 able resemblance in certain points of the affection. There 

 were scars or wounds, and decay of the tips of the branches ; 

 but there was, in addition, a peculiar shrinking and 

 cracking of the skin generally, close above or below or all 

 round the bases of the twigs. In cutting deeply into the 

 branch the green layer under the epidermis and the 

 cambium layer were seen to be discoloured. There was no flow 

 of viscous liquid traceable, as the branches had been cut off 

 in winter and before the flow began. There was dried 



* Yearbook of the U.S.A. Department of Agriculture, 1895. 



