MAINE APPLE DISEASES. 3/3 



branches, and all old neglected trees such as one frequently sees 

 along the roads and burn them. Branches which show bad can- 

 kers should be cut off back of the canker and burned. In the 

 case of young cankers, the branch can frequently be saved by 

 cutting away the diseased tissue down to healthy wood, disin- 

 fecting with a solution of copper sulphate, one ounce to one 

 gallon of water, or corrosive sublimate, one part to looo of 

 water, and then painting over with pure white lead in boiled 

 linseed oil or coating with a good quality of grafting wax. The 

 trees should be gone over carefully a number of times each year 

 and developing cankers and wounds should receive attention. 

 Spraying for apple scab will help to control the cankers by 

 reducing the amount of material for infection and by covering 

 wounds with the fungicide. All decayed fruit should be de- 

 stroyed, since the black rot of the fruit and this canker are 

 caused by the same fungus. The treatment outlined should go 

 far toward controlling cankers caused by other fungi in this 

 State. 



Bitter rot canker. This canker caused by the fungus which 

 causes bitter rot of the fruit is of rare occurrence in Maine. 

 On the dead bark the fungus produces little black pustules from 

 which, when they are mature, pinkish masses of spores exude. 

 The spores from cankers cause much of the early infection of 

 fruit on the tree each year. The appearance of the diseased 

 bark of a young tree caused by inoculation with the bitter rot 

 fungus is shown by Fig. 260. 



Myxosporimn canker. The fungus causing this disease has 

 been much confused in the past with Sphaeropsis malorum. 

 Edgcrton's* study of the fungus has shown that the two are 

 entirely distinct. This fungus is of very frequent occurrence 

 in Maine, but its economic. importance in this State is somewhat 

 in doubt. So far as observed the damage which it does is con- 

 lined to killing outer portions of the bark on old limbs and the 

 killing Ijack of the bark on younger limbs and twigs rather than 

 to the production of true cankers. On such branches the fruit- 

 ing pustules arc found on the part which was first killed. The 

 dead bark is separated from the healthy bark by a sharp line 

 and is sunken as is shown in Fig. 261. The appearance of these 



* Edgerton, C. W. Two little known Myxosporiums. Annales 

 Mycologici VI : 47-52. 1908. 



