ON A DISEASE OF THE BEECH CAUSED BY BULGARIA POLYMORPH A WETT
Annals of Applied Biology
With Plate I . ) During the last few years, a number of t h e pollard beech trees a t Burnham Beeches have suffered from a disease which has apparently caused the death of several specimens, and is seriously affecting some others. At various points on the surface of the bark a brown liquid exudes which rapidly concentrates to a dark viscous gum', collect,ing in gouts near the point of exit and, if in quantity, trickling down to lower levels. The material is partially soluble in water, with the
... in water, with the result that in wet weather it is washed down and may be thus distributed over a considerable area of the lower part of the trunk. The effect is very unsightly and the trees attacked are readily detected (Fig. 1) . Frequently the gum provides a medium for t,he growth of various saprophytes, yeast, bacteria, moulds, &., and t,hen becomes of a creamy consistency and buff or pinkish in colour. The bark from which the gum proceeds is already dead, and since the affected areas are often rapidly extended, the life of the tree may be seriously threatened. These pollards are probably some of the oldest beeches in existence. Their life has been prolonged far beyond what is generally regarded as the normal limit of the species by the systematic pollarding, whichas was usual in ancient forestry-was done a t such a height as to protect the young shoots from browsing animals. The cessation of cutting, however, permitted the growth of a few o€ the more favoured shoots and the trees now bear severiil fine limbs rising from the crown. The symptoms of the disease are very marked. The effect on the tree is very serious. This substance has been referred to throughout a8 gum, though its exact nature has pot yet been determined.