APPLE DISEASES 75 



courts. The mycelium lives over in the tree from year to year 

 and the sporophores live for several years. One case is 

 recorded where the sporophore reached an age of eighty years. 

 Each year the mycelium making the sporophore fills up the old 

 tubes and builds on a new layer of pores just below the layer 

 of the preceding year. 



Control. 



For the orchardist, it will be well to consider the possible 

 source of the trouble. It has been pointed out that the disease 

 may be found on a wide range of broad-leaved trees. Should 

 the orchard stand in close proximity to the forest, more than 

 the usual amount of trouble may be expected to ensue. In 

 such an event the destruction of diseased forest trees and the 

 removal of sporophores become important. Perhaps the 

 most important matter after all is the avoidance of wounds. 

 Pruning wounds should in no case be left uncovered ; a wound- 

 dressing should be applied within a short time after pruning 

 operations. Coal-tar will be found entirely satisfactory. 



The making and handling of cuts have been discussed on 

 page 53. In cases where trees are already affected with 

 heart-rot the treatment of such areas is an important matter 

 in the control of the disease. It should be borne in mind that 

 the normal heart of a tree is practically dead tissue. It gives 

 only rigidity, and may be completely removed without infrac- 

 tion on the normal functions of the tree beyond impairing its 

 strength, which is a serious consideration, however, because the 

 limbs may be broken, or the tree may be blown over by the 

 wind. Decaying wood can be of no use to a tree ; on the other 

 hand, it may act detrimentally and should therefore be re- 

 moved. The operation should be thorough, all decayed wood 

 being removed. A mallet, a chisel and a gouge are the chief 

 tools needed. If the rot extends for a considerable distance 

 down the limb, a hole, which will serve as a drain, should be 

 bored at the lower extremity. Cavities in shade and orna- 



