The Development of Gnomonia erythrostoma, Pers. 
The Cherry-Leaf-Scorch Disease. 
BY 
F. T. BROOKS, M.A. 
Senior Demonstrator of Botany, Cambridge University. 
With Plates XLVIII and XLIX. 
I N 1886 Frank ( 17 ) gave a short account of the development of this 
Pyrenomycete and showed that it was the cause of an epidemic disease 
of Cherry trees in the district of Altenlande in Germany. The chief 
features of the life-history of the fungus as described by Frank may be 
summarized as follows :— 
Infection of the leaves first takes place in the spring, and the mycelium 
which develops in them passes towards the base of the leaf-stalks where it 
prevents the formation of the absciss layer. By this means infected leaves 
do not fall in the autumn but remain hanging on the trees to cause infection 
of the new foliage in the following spring. Where the mycelium is present 
in the leaves, spermogonia giving rise to spermatia, and coiled structures 
with trichogynes, are found. Frank considers that the spermatia fertilize 
the coils, after which the latter develop into perithecia which liberate their 
spores in the spring. Frank’s brief account only dealt with the grosser 
development of the fungus, and it was obvious that a cytological investiga¬ 
tion was to be desired. The absence of figures of the ascogonia, trichogynes, 
&c., in Frank’s account, and the lack of detailed knowledge of the develop¬ 
ment of the perithecium of the Pyrenomycetes generally, made this all the 
more imperative. 
The present investigation was begun at the suggestion of Professor 
V. H. Blackman, to whom I am much indebted for advice and criticism. 
Material was obtained from the Cherry-growing districts of Kent, where 
the disease caused by Gnomonia erythrostoma is known as the ‘ Cherry 
Leaf Scorch ’ on account of the appearance presented by the retained 
foliage of infected trees in autumn and winter. At the outset of the 
investigation attempts were made at Cambridge to cause infection of some 
of the varieties of Cherries most susceptible to this disease. For this 
purpose specimens of such trees were obtained, and in the spring, at the 
[Annals of Botany, Vol. XXIV. No. XCV. July, 1910.] 
