83 



ments for their growth and distribution. For this reason the fungus of the 

 so-called larch canker, the Dasyscypha (Pesk.a) U'UlkommU, is so abundant 

 in old larch plantations and the trunks of the young cop'^e wood are covered 

 with lichens. 



The complaint that the trees in northwest and middle Germany and in 

 France, on an average, show no satisfactory growth is explained by these 

 conditions of growth on the plains diametrically opposed to the nature of the 

 tree. This is also the reason for the reaction which has taken place in the 

 usual enthusiasm of foresters for the cultivation of the larch. 



The comprehension of our mistakes in growing the larch and the in- 

 tenability of the widespread assum.ption that it can be grown in any place 

 has recently been gathering force in forestry circles. A little paper publish- 

 ed by the First Commissioner of Woods and Forests in Hameln^ is 

 ot the greatest significance. He observed that the larch canker occurs only 

 \\'here the tree is grown under hindering conditions or is crowded by its 

 neighbors. The point which he makes strongly is "that the sun is the nurse 

 of the larch." Com.plete agreement with this discovery has com.e from an 

 extensive inquiry on the part of the English Dendrological Society contained 

 in Sommerville's reports-. From this report canker seems to be in- 

 creasing in England on the larch and attacks trees from seven to fifteen 

 years old most easily. Dampness in dense growths favors the disease which 

 occurs less often on altitudes than in hollows. Many practical foresters 

 maintain that the disease is inherited through the seed ; aiid, while Sommer- 

 ville does not share this point of view, he cannot dispro\e the assumption of 

 an hereditary predisposition. Also the assertion that nurseries spread the 

 disease may not be repudiated entirely. 



We completely understand such statements also heard frequently in 

 Germany. Such predisposition to sickness lies in the changed mode of 

 grow^th which is a result of the removal of the tree frf-m mountains to 

 plains, thus destroying its natural immunity. It is reasonable that nurseries 

 with their rapid forcing of the seedlings in manured soils, excusable because 

 of agricultural reasons, increase this weakening of the larch. W^e find simi- 

 lar conditions also for other conifers ; for example, we have examined pine 

 seedlings from nurseries and forestry seed-beds which had begun to suffer 

 from leaf cast, and we have always been able to prove that the beginning of 

 resinosis was present even in the iirst annual ring. 



Weber^ observed in beech foliage conditions similar to the larch 

 in regard to the difference in the ash content. From in\estigations from 

 eleven different habitats it was found that the percentage of ash in beech 



1 Die Larche, ihr leichter und sicherer Anbau in Mittel-und Norddeutschland 

 durch die erfolgreiche BekJimpfung- des Larchenkrebses. Leipzig- 1899. 



- Report by Dr. Sommerville on the inquiry conducted by the Society into the 

 disease of the larch. Transact, of the English Arboricultural Society. Vol. Ill, 

 Part IV. 1893-94. 



3 Weber, Einflufs des Standorts auf den Aschengehalt des Buchenlaubes. Allg-. 

 Forst.-u. Jagdzeitung-, 1875, p. 221, cit. in Beidermann's Centralbl. f. Agrikultur- 

 chemie, 1875, II, p. 325. The percentage of ash content and especially of calcium 

 and silicic acid becomes greater the more slowly the plants grow. 



