24 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



to luxuriant development and ripened their spores on the blisters, 

 whOe the spores found ample opportunity of germinating, and of 

 infecting the trees in the close pure woods. To-day but few of 

 the many promising young woods remain. The larches have 

 maintained their ground best in those woods where a few were 

 introduced as advance-growth. The air circulating in the freely 

 developed crowns has not only kept the disease in check, but has 

 also prevented the spores from ripening on diseased specimens. 



Supposing that we have to do with a diseased larch wood, it 

 is first necessary to detei-mine whether the damage is entirely due 

 to the moth, or whether it is a case of fungoid blister. 



Often enough both will appear in company. If it is simply 

 a case of stunting in consequence of the attack of the moth, 

 pruning away the branches till only the vigorous upper part of 

 the crown remains may be permanently beneficial. The upper 

 branches will grow vigorously, and may form a good, perman- 

 ently healthy crown, especially as the moth is most destructive 

 on the lower branches. 



If it is a case of fungoid injury, pruning may assist somewhat 

 only if the bole as a whole, and especially the part in the crown, 

 is sound. If a tree is in vigorous growth, the smaller blisters 

 low down on the stem, although they increase in size, will induce 

 death only at an advanced age. 



Blisters on the branches are, in themselves, of less importance. 

 They merely contribute to the danger of the further spread of the 

 disease by means of spores. 



As regards the future cultivation on plains and at moderate 

 elevations of this so essentially valuable tree, the following points 

 ii^ay be noted in the light of what has been said. It should only 

 be gi-own singly — that is to say, it should form but a small part 

 of a mixture, and it ought, if possible, to be planted somewhat 

 in advance of the other trees. It should never be planted in pure 

 woods, and should always occupy an open situation. Where 

 diseased woods are present in the immediate neighbourhood, it 

 is better to abandon the idea of cultivating this tree. The 

 greatest caution is to be exercised in procuring young trees from 

 outside sources, and plants showing any signs of disease in the 

 seed or plant beds must at once be removed and burned. 



