HEART-ROT 123 



mycelium is incapable of growing in it. Thus a trench 

 filled to the surface with lime -might prove to be an effective 

 barrier. But conidia and spore infection through the air 

 is probably too common to make such a trench worth the 

 labour of digging. Vigilance and forethought will help us 

 much more than trenches. Heart-rot is a particularly 

 insidious disease because its presence is not generally dis- 

 covered till the trees are cut, so that not only have the 

 trunks been getting more and more rotted, but they have 

 been filling for many years a plot that might have been 

 earning a useful rent. A skilled woodman can generally 

 distinguish pumped trees by the hollow sound they emit 

 when struck with the back of an axe or a stick, and by 

 this time they are often ' gouty ' at the base. But these 

 means do not aid in the discovery of the disease till much 

 damage has been done. Testing a tree with an increment 

 borer, however, will disclose the presence of heart-rot as 

 soon as the trunk is affected, and it is recommended that 

 foresters should test their larch plantations from time to 

 time with this instrument. It should be remembered that 

 trees usually become pumped in groups, and if every tenth 

 tree is bored every other year, an epidemic will be dis- 

 covered before the loss or value becomes serious. Where 

 one tree is found to be attacked, others in the immediate 

 vicinity must be bored, and all the trees that are diseased 

 should be cut out. They will only be wasting themselves 

 and the land on which they are growing. Sometimes it 

 may be necessary to clear fell, and in this case it is safer 

 to grow a rotation of broad-leaved trees before replanting 

 with larch or other conifer. 



Land which is being afforested for the first time presents 

 a special case. Here pumping must be anticipated, and yet 

 the exclusion of larch and spruce, and to a less extent 

 Scots pine, would prove a serious obstacle in afforesting 

 new land. Either the conifers may be grown in a mixture 

 with hard woods and the former removed in the earlier 

 thinnings, or, where it is thought advisable to plant pure 

 coniferous woods, the forester must watch them carefully 



