FORESTS 



FORESTS 



345 



stumps, and the like, so that the method of control 

 is practically the same as that recommended for 

 the oak timber worm, especially as applied to 

 chestnut and red oak. 



General advice. 



It should be remembered that after a tree is 

 once attacked and seriously injured by one or more 

 of these wood-boring insects, nothing can be done 

 to repair the damage, and that therefore preven- 

 tion is of primary importance. Thus it will be 

 seen that the control of an outbreak of any of the 

 principal insect enemies of the woodlot involves 

 the adoption of methods of management by which 

 the utilization of the infested trees at the proper 

 time will destroy the insects and bring about the 

 desired results with little or no additional expense, 

 and this is to be supplemented by other features 

 in the management which will prevent future 

 trouble. 



Some of the rules of general application are as 

 follows : 



Fell and utilize or destroy, in the fall or winter, 

 all dying or recently dead trees before the broods 

 of destructive enemies have had time to develop 

 and emerge ; utilize or destroy all tops, large 

 branches, and logs from living trees cut the pre- 

 vious winter, spring and summer, and burn the 

 brush over the stumps. 



Avoid injury of any kind to the bark and wood 

 of living timber, especially of oak and chestnut. 



Cut and utilize the old trees which show evi- 

 dences of deterioration, and those which have been 

 injured by lightning, storm or other causes ; and 

 if the trees are infested by destructive insects, do 

 the work in the fall and winter. 



Forest and Timber Diseases. Figs. 492^97. 

 By Hermann von Sehrenk. 



The diseases which affect forest trees manifest 

 themselves in various ways, depending on the part 

 of the tree which is attacked. Diseased trees may 

 be recognized by the yellowing or other discolor- 

 ation of their leaves, a much reduced growth of the 

 trunk and branches, the dying of the tops, the ap- 

 pearance of swellings on leaves or branches, and 

 by the growth on trunks or branches of punks or 

 toadstools. A diseased tree forms less wood than a 

 healthy one, and in many cases decays at the heart, 

 (Fig. 492), with a resultant total destruction of 

 the wood, and ultimate death. 



Trees are liable to become diseased from the first 

 year on. They are most liable during the latter 

 part of their life. A number of fungi attack seed- 

 ling trees and cause their death, by strangling them 

 or by killing the young leaves. As the trees grow 

 older, the destruction of certain branches and leaves 

 may not have any very serious results ; but after 

 they have reached a period of maturity, they 

 become more subject to disease, because larger 

 branches will be broken off ; and more wounds are 

 made in old trees than in young ones. Practically 

 all kinds of trees are subject to disease, and some 

 more than others. The redwood, cypress and the 



various cedars are comparatively free from disease ; 

 so, also, are trees like the red gum, sycamore and 

 sassafras. The oaks, beech, birch and other hard- 

 woods are rarely attacked when young, but become 

 very liable to disease after they have reached the 

 age of fifty years or more ; the same is true of 

 pines, firs and spruces. 



Causes of disease, and points of attack. 



Diseases of forest trees may be due either (1) to 

 unfavorable conditions of soil and climate, or (2) 

 to parasitic enemies, as insects, fungi and higher 

 plants. Wet, soggy soil will produce stag-headed 

 trees ; excessive quantities of sulfur gas in the air 

 will result in a discoloration of the foliage of the 

 entire tree, and frequently in its ultimate death. In 

 dry years there will be very much less disease than 



Fig. 492. Section showing how fruiting body of wood-destroy- 

 ing fungus grows, and the resulting internal rot. 



in years of heavy rainfall. Trees that are grown 

 very close together will be much more subject to 

 disease than those that are farther apart. Wood- 

 lots in which all of the trees are of one kind will 

 be much more liable to disease than woodlots in 

 which different kinds of trees are grown. In seed- 

 beds, diseases will be favored by poorly drained 

 soil and by excessive mulching. Thrifty trees will 

 always be very much less subject to disease than 

 weak ones. 



The diseases due to fungi can be divided into 

 (1) diseases of the living parts, and (2) dis- 

 eases of the dead parts. The diseases of the living 

 parts affect the leaves, the younger branches and 

 the smaller roots, and a thin layer of the body 

 of the tree, including the most recently formed 

 wood and the inner bark. The diseases of the 

 dead parts affect the older wood of the trunk, 

 roots and branches, known as the "heart-wood." 

 The fungi that cause disease of the living parts 

 bring about local or general disturbances, which 

 at first weaken the tree and may ultimately kill 

 it ; those that attack the heart-wood bring about 

 the decay of the heart-wood, resulting in the loss 

 of wood, and when the decay goes far enough, 

 in the weakening of the tree so that it is easily 

 broken off. 



