294 ENGLISH ESTATE FORESTRY 



the fact that the mycelium was eating its way into the latter. 

 In such cases it is possible to remove the entire diseased area 

 with the point of a knife during the summer, as it will slip 

 out like an acorn out of its cup, owing to the cork layer which 

 separates the dead and living tissues. 



Leaving the opinions or theories of the scientists for a 

 time, let us look at those advanced by practical foresters, 

 which, from a forestry point of view, are equally as important. 

 The most prevalent are those which attribute the existence 

 of the blister to frosts in April and May, at a time when the 

 dwarf shoots are coming, or have come into leaf. The injury 

 done to larch by these frosts depends a good deal upon their 

 severity in the first place, and upon the state of the trees 

 when the frost comes in the second. What may be termed a 

 ground frost of five degrees or less rarely cuts larch back, 

 unless it happens to be seedlings or young trees of not more 

 than 3 or 4 feet high. Now ten degrees of ground frost are 

 not uncommon in March, but it is seldom that larch is far 

 enough advanced in that month to suffer from them, although 

 in early districts a certain amount of damage is undoubtedly 

 done in this month. But in the south of England, April 

 frosts of more than two or three degrees are not common 

 except in low-lying hollows, in which frost is almost of 

 double intensity to that on high ground. But in all cases 

 frost injuries are most severe at the surface of the soil on 

 low flat ground, and decrease the higher the leaves or 

 branches stand above it, or the surface rises above the 

 general level ; and one can almost define the level of the 

 frost-line in a coppice or plantation, to a foot, which has cut 

 back the tender shoots as late as the month of May. If 

 spring frosts are sufficient in themselves to account for larch 

 blister, therefore, we ought to find it more numerous on the 

 branches near the ground, and on trees growing in low-lying 

 situations, than on branches higher up the stem, or on trees 

 on hillsides or eminences. Yet, when we come to test this 

 theory on the ground, can any conscientious observer 

 maintain that it is supported by facts, or that facts justify 

 one in forming a theory on such a basis ? 



That spring frosts do injure larch to a great extent no 

 reasonable individual would attempt to deny ; but, when an 



