Larix 363 



by frost, weight of snow, insect punctures, or otherwise, and that it is usually worst 

 in sheltered hollows, where damp air lies and spring frosts are severely felt, and 

 that on high situations facing north and east the disease rarely causes much 

 injury. 



All this I admit in full, but I am also convinced that, as the spores of the 

 fungus are now so generally present everywhere, it is impossible to eradicate it, 

 the only way by which it can be combated is by planting only on soils and in 

 situations which experience has shown enable the tree to grow vigorously, and on 

 poor and dry soils mixing it with hardwoods, the fall of whose leaves enriches the soil 

 and keeps it cool and free from grass. 



Heart-Rot in Larch. — Though sometimes confused with Peziza by careless 

 observers, this is a totally different disease. C. M'lntosh^ describes it very fully, 

 and Hartig refers to it under the name of root-rot. Forbes believes, as I do, that 

 it is the direct result of unsuitable soil, either too wet or too dry. It is most 

 common on very poor limestone, sand, and chalk, but also occurs on clay and 

 gravelly soils. In my experience it is especially noticeable where larch follows 

 larch on soils containing insufficient nourishment, and can only be avoided by not 

 planting larch where it is found to be prevalent. It usually attacks trees of about 

 twenty years old, when they have got over their first period of vigorous growth and 

 have practically exhausted the available sources of nutrition. According to Mr. 

 Simmonds, late Deputy Surveyor of Windsor Forest, larch grown on what is called 

 iron pan in that district gets red rot at the heart and is then said to be " pumped." 



Larch Bug. — What is commonly known as larch aphis or larch bug is an insect 

 called Chermes laricis. The life-history of this insect is at present somewhat obscure, 

 some continental observers believing that it passes through an intermediate stage of 

 existence on the spruce, as no males have yet been found on the larch, in which case 

 it is evident that the insect cannot spread or become numerous unless spruce exists 

 in the neighbourhood. But this is contested by Dreyfus, and I have observed 

 that in England at any rate it multiplies exceedingly where no spruce are near. 

 The females pass the winter under the bark, and are wingless, oval, of a purplish- 

 black colour, and have a long bristle-like sucker through which they feed on the sap 

 of the leaves. In spring they lay eggs which produce young, which grow rapidly, 

 and are covered later by a whitish woolly down, and when numerous give the trees a 

 whitish appearance. They increase rapidly by successive broods, and seriously 

 weaken the constitution of the trees when young, rendering them especially liable to 

 succumb to the attacks of Peziza, which often accompany and succeed them. When- 

 ever I have seen bad attacks of the bug I have noticed that the Peziza is more than 

 usually destructive, and it seems as though the climatic conditions which favour the 

 one also favour the other. In the autumn the bark of the trees in a badly attacked 

 plantation appeared quite black ; and though this plantation was in a high situation, 

 exposed to the east, and was heavily thinned the year afterwards, the greater part of 

 the trees, which were thirteen years planted from Tyrolese seed, and had been 

 growing vigorously at first, were so sickly on the thinner and drier parts of the land 



' The Larch Disease (iS6o). 



