NOTE ON THE LARCH DISEASE. 



41 



nurseries, aad the disease was carried from place to place. 

 Where the larch throve best was in mixed woods, where it had 

 a stare of the other trees, and its crown exposed to the free 

 cii'culation of the air. The following extract from Prof. Marshall 

 Ward's valuable book on Disease in Plants, p. 152, will show 

 how the conditions on the low ground made the cultivation of 

 the larch unsuccessful. " The larch fungus is also to he found 

 on trees in their native Alpine home, but there it does very little 

 damage, and never becomes epidemic, except in certain sheltered 

 regions, near lakes and other damp situations. How, then, are 

 we to explain the extensive ravages of the larch disease over the 

 whole of Europe during the latter half of this century ? The 

 extensive plantings providing large supplies for the fungus does 

 not explain it, because there are large areas of pure larch in the 

 Alps which do not suffer. In its mountain home the larch loses 

 its leaves in September, and remains quiescent through the 

 intensely cold winter until May. Then come the short spring 

 and rapid passage to summer, and the larch buds open with 

 remarkable celerity when they do begin, i.e., when the roots are 

 thoi'oughly awakened to activity. Hence the tender period of 

 young foliage is reduced to a minimum, and any agencies which 

 can only injure the young leaves and shoots in their tender stage, 

 must do their work in a few days, or the opportunity is gone, 

 and the tree passes forthwith into its summer state. 



"In the plains, on the contrary, the larch begins to open at 

 varying dates from March to May, and, during the tardy spring, 

 experiences all kinds of vicissitude?, in the way of frosts and 

 cold winds, following on warm days, which have started the root 

 action ; for we must bear in mind that the roots are more easily 

 awakened after our warmer winters than is safe for the tree. 



" It amounts to this, therefore, that in the plains the long 

 continued period of foliation allows insects, frost, and winds, etc., 

 some six weeks or two months in which to injure the slowly 

 sprouting, tender shoots, whereas in the mountain heights they 

 have only a fortnight or so in which to do such damage. That 

 the low^er altitude and longer summer are not in themselves 

 inimical to the larch is proved by the splendid growths made by 

 the trees, first planted a century ago. Then came the epidemic 

 of larch disease; the fungus, which is merely endemic — i.e., 

 obtains a livelihood here and there on odd trees or groups of 

 trees in the warmer or damper nooks in the Alps, — was favoured 



