THE ENEMIES OF ENGLISH WOODLANDS 299 



the same square mile, it is not unreasonable to lay particular 

 stress on the question as to why the disease (if the disease 

 be the cause) produces a harmless effect in the one case, and 

 a destructive effect in the other ? 



The simplest way to answer this question, if it can 

 be answered, is to consider the prevailing conditions under 

 which most diseased plantations are growing, and notice 

 wherein these conditions differ from what is usually regarded 

 as the ideal. Larch plantations may become badly affected 

 with disease from the time of planting up to twenty years 

 of age, and occasionally older plantations are subject to 

 attack. As a general rule, however, from five to twenty 

 years may be considered the critical period in the life 

 of a young plantation, and, if it reaches the latter age without 

 showing serious signs of injury, little anxiety need be felt 

 regarding it, so far as the genuine blister disease per se is 

 concerned. When plantations are diseased before the age of 

 five years, it may be safely concluded that either the plants 

 were diseased when planted, or that the conditions under 

 which they were planted were very far from right. It 

 would, we suppose, be rank heresy to suggest that the larch 

 disease exists in public nursery stock, although no good 

 reason can be given why it should not. As a matter of fact, 

 however, there is probably little to complain of in this 

 respect, and it may be taken for granted that the plants 

 become diseased after they have been planted out. 



What, then, are the usual conditions under which larch 

 is obliged to exist for the first five years or so after planting ? 

 On heathy soils and moorland this tree is usually slitted or 

 notched, not necessarily, into the soil, but into the upper six 

 inches of material nearest the surface. On heathy soils 

 three or four inches of this material often consist of dry peat, 

 full of the roots of heath or grass. In such cases only the 

 extremities of the larch roots come in contact with the true 

 soil below, and with careless slitting they may only rest on 

 the top of it, as on gravelly soils it is often difficult to get 

 the spade far into the gravel. Planted under such conditions 

 in the spring, what chance has a young larch to grow during 

 a dry summer ? In the first place, it has to form new roots 

 in a soil which is not only poor in itself, but is also suffocated 



