438 BOAKD OF AGRICULTUBE. 



to this. As, however, the mummied fruit commonly falls to the ground 

 the matter remained a puzzle as to how the spores could rise to the tree. 

 The new observations recently made by us in many orchards showed that 

 the limb canker Was in every case the source of primary infection, and 

 therefore these cankers are much more dangerous than the old mummies. 

 It is not usually easy to discover the cankered spot from the ground, but 

 it is easy to locate it by the diseased spots on the apples. With a little 

 practice, any one with eyes sharp enough to detect these latter can 

 quickly find the former. It seems, therefore, entirely feasible to prevent 

 further infection by a critical examination of the trees at this time of 

 the year and the removal of the cankered limbs and the fruits already 

 diseased from it. 



What the Canker Looks Like. 



Canker occurs on limbs of any size— from those of an inch or two in 

 diameter to last year's fruit spurs. More commonly the spot is two to 

 four inches long. The affected portion is killed by the fungus and the 

 new growth rises as a rim of healing tissue about its border. The spot is 

 therefore sunken to the extent of the later increase in diameter of the 

 limb. It is rough and black and has somewhat the appeai*ance of an old, 

 ragged wound as often results from many causes. By close observation 

 it will be seen that the old bark of the killed portion is still present, 

 though usually variously ruptured and sunken. The fungus which causes 

 the bitter rot of apples is present in this old bark and bears the spores in 

 clustered masses over its sin-face, from which they are washed by the 

 rain to the fruit as described. So far as observed, these cankered spots 

 are few in number, except in the case of one variety, that of the Hunts- 

 man, where they are found to be very numerous. More often only a tree 

 here and there in the orchard has a cankered limb. 



Preventive Measures. 



From what is now known, the following preventive procedure is ad- 

 vised: Examine the orchard tree by tree, following systematically the 

 rows— perhaps on horseback or in some way to look down as much as 

 possible upon the fruit, the infected spots being usually on the upper 

 surface of the apple. At this time of the year these spots are brown, 

 circular and very slightly depressed and show clearly against the light 

 or reddish color of the apple. As soon as one spot is found, search for 

 others and .iiist above the uppermost ones look for the cankered limb. 

 This limb is sure to be in such a position that spores may be washed from 

 it onto the spotted fruit. It will now be an easy matter to cut away the 

 diseased limb and to remove the infected fruit below it. It will be safer, 

 however, to take all the apples from that portion of the tree subjected to 



