THE POPLAR. 329 
Pruning is not to be recommended for the poplar. The 
species which ramify, :uch as P. canescens and P. monilifera, 
can be grown with clean trunks by being inserted <> that they 
will gently press on one another, which will have the effect 
of diminishing the vigour of the side-branch<:, and of pro- 
ducing clean timber. In amputating a large branch, unless 
skilfully performed =o as that the wound will not lodge 
water, the tree is apt to suffer. The wood being extremely 
soft is apt to crack and admit moisture into the tree, which 
becomes ruinous. For this reason none of the species can be 
relied on a: coppice-wood for more than a crop or two. 
Disease —The poplar furnishes food for the larvez of several 
species of moth; but I have never found the tree assailed to 
any serious extent by imsects, or any disease except the atmo- 
stherie blight known as the potato disease, and its influence 
was confined purely to the varieties of P. alba. The nearly- 
related species, P. canescens, on the most trying visitation: of 
this influence, I have found always exempt from injury when 
growing in the same quarter. It was noticed that the finer 
the varieties of the tree, or those that produced the greatest 
contrast in the colours of the leaf, were the sort: on which the 
disease fell with the greatest severity. My experience of this 
disease was not confined to one locality. I have seen the 
influence most distinctly m various places, some of them 100 
miles apart. About twenty year: ago my attention was first 
directed <4 it early in August, one year when the potatoes in 
the fields had flagged and fallen by the disease. I observed 
in the stool ground, or propagating ground, in the nursery, 
the drooping leaves of the white poplar to have fallen - 
taneously with those of the potato. I found afterwards that 
during a succession of bad years of the potato disease the 
stools of this species of poplar died along with those of the 
Svlanum variegatum, or shrubby potato, situated in the same 
propagating ground. At the same time the trees of the white 
poplar throughout the country became much enfeebled, and 
showed quantities of dead branches, and in many districts the 
tree is now :+ldom met with where it formerly abounded. 
