296 ENGLISH ESTATE FORESTRY 



still oftener on branches too small to carry more than a few 

 grains of snow at the most. In fact, the more one ponders 

 on this theory, the more one is convinced of its unsoundness, 

 and it may be put on one side as exploded. 



Another theory, which has found much favour at one 

 time or another, is that which attributes the disease to cold, 

 wet soils, tending to produce badly ripened wood. When 

 larch is diseased on such soils, it is quite possible that badly 

 ripened wood has something to do with it, as we know, by 

 experience of other trees and parasitic fungi, that badly 

 ripened wood is most susceptible to attack. The larch has 

 a great tendency to prolong its growth well into September, 

 and when the succeeding October is wet and cold, and 

 accompanied by frosty nights, the last year's growth runs a 

 great risk of getting cut back when severe weather sets in 

 later on. The ends of shoots thus damaged facilitate spore 

 infection to a much greater extent than ordinary wounds. 

 In its capacity as a saprophyte the fungus attacks these dead 

 ends, vegetates within them for a time, and ultimately finds 

 its way to otherwise healthy tissue. When small branches 

 near the main stem are cut back in this way, the dead branch 

 often forms the nucleus of a blister which may prove 

 permanent, and considerably depreciate the market value of 

 the tree. But, as blister is quite as prevalent and destructive 

 on dry soils as on wet, it is obvious that the occurrence of 

 the disease on the former is not explained by the theory that 

 badly ripened wood is the sole cause of it, although it may 

 quite possibly be one of the causes when the conditions are 

 as stated above. 



The theory that larch has deteriorated through the use 

 of home-grown or badly selected seed has received the 

 support of many experienced foresters of late years. It is a 

 well-known fact that many breeds of plants and animals 

 deteriorate when bred away from their native habitat, and 

 that it is necessary to constantly introduce fresh blood from 

 the original stock in order to preserve their stamina and 

 constitution. This deterioration is all the more likely to 

 occur in the case of a breed originating in a cold climate and 

 transferred to a warmer one. The more stimulating and 

 exciting conditions bring about a more rapid but less robust 



