THE SYCAMORE SOOTY BARK FUNGUS 15
P. H. Gregory, del.
Fig. 1. Diagram of Cryptostroma corticale on thin-barked specimen of Acer
pseudoplatanus, x 50 approx. Pg., phellogen; R, roof stroma; Col, columns;
Cap, capillitium; Sp, spore mass; Phi., phialide layer; F, floor stroma; Phl,
phloem; C.S., cambial stroma; M.R. medullary ray. (From: Trans. Brit.
mycol. Soc. 34,585, 1951).
Before death of the affected part of the tree and sporulation of
the fungus other symptoms of infection can often be found. Some-
times before any other external signs of disease are present, the
leaves on one or more branches wilt suddenly. Early stages of in-
fection are also associated with characteristic yellow to brown
staining of the wood.
There are many questions about the fungus to which we have