238 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



named the fungus Diaporthe parasitica. It appeared three 

 years ago, and the disease immediately assumed an epidemic 

 character. Numerous instances have occurred of attack by 

 both insects and fungi which have reached Europe from over 

 seas ; who can say that our own chestnuts will not soon become 

 infested with this new parasite ? 



The disease is spread by means of spores carried by wind, 

 birds, squirrels, insects, or otherwise. The spores enter the tree 

 through wounds on the trunk or branches. From the point of 

 entry the mycelium spreads in all directions into the liber and 

 cambium, until it completely encircles the trunk or branch. 

 Several of the outer wood-rings may be penetrated by it, and it 

 probably enters the medullary plates in search of the reserve 

 material that they contain ; but the chief seat of the disease is 

 the inner bark and the cambium layer. 



In the early stage, the presence of the disease is not easily 

 detected. It usually first attacks small branches, which are 

 speedily encircled by it; and, when this has been effected 

 their foliage turns yellow and subsequently withers. The 

 attack then becomes very conspicuous ; it is developed in a 

 clearly defined ring, the effect of which might have been 

 produced by a deep incision round the trunk or branch. The 

 girdled stems or branches do not, however, usually completely 

 die until the second year of the attack. There has been no 

 previous instance of aerial fungi killing, within the space of two 

 years, and over large areas, trees of the dimensions shown in 

 the photographs received from America. No fewer than 1400 

 attacked trees have been felled in Brooklyn Park, New York, and 

 in another of the city's parks there are 4000 sweet chestnuts, of 

 which many are already dead, while it seems improbable that 

 any of those still living will ultimately survive. 



The sweet chestnut is extensively cultivated as a forest-tree 

 in the United States. Its timber being very durable, it is much 

 used for posts, poles, and railway sleepers, while it is also 

 valued by cabinet-makers. After the White (Weymouth) pine, 

 it is, probably, the most profitable of the forest-trees grown in 

 the States. 



M. Henry describes certain diseases which, in Europe, attack 

 chestnut trees, especially grafted trees, grown for the sake of 

 their fruit, but also attack those grown for the sake of their 

 timber. F. B. 



