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- 
