68 
Frederick A. Wolf, 
permitted to overwinter in wire baskets out of doors no evidence has 
been found of the occurrence, on them, of an ascigerous stage. On the 
contrary acervuli, bearing conidia which germinated within 24 hours in 
water culture, were still present April 24, 1913, on diseased leaves which 
had been collected during the previous autumn and had been exposed 
to conditions comparable to those presented to fallen leaves in the grove. 
Since the fungus remains viable in the conidial stage upon fallen leaves 
until the trees are again in full leaf it seems quite probable, at any rate, 
that no ascigerous stage exists, at least in this vicinity, for this species 
of Cylindrosporium. It is not improbable also that under certain environ¬ 
mental conditions a perfect stage might develop since some species of 
this genus are known 4 ), to possess an ascomycetous form. 
That this disease may be quite easily controlled has been demonstrated 
by some experimentation conducted during the past summer. The diseased 
fallen leaves had been gathered up, from beneath the trees upon which 
the fungicides were to be used, and destroyed, during the autumn, in 
order to lessen the chances of infection from this source. Certain of the 
trees were sprayed with self boiled lime sulphur, 8 — 8—50, the first 
application being made May 3 rd , at a time when the newly formed leaves 
had almost attained their mature size. A second application was made 
on July 2 nd . By July 29 th , a considerable amount of spotting, comparable 
to that on the untreated trees, had developed, indicating the ineffectiveness 
of this fungicide. Several trees, however, were sprayed with Bordeaux 
mixture, 4—4—50, the first application having been made on July 31 st , 
and a second on Aug. 27 th . It is to be noted that leaf spot had already 
appeared on these trees when the first spray was applied so that it was 
only hoped to check the disease. This end was very satisfactorily attained 
and these trees retained their foliage until the frosts caused them to fall. 
As a result of this work it may be recommended that a satisfactory control 
of walnut leaf spot may be obtained by the destruction of diseased leaves 
during the trees’ dormancy, and by the application of Bordeaux mixture, 
as a supplementary measure, at the inception of the disease. 
While searching available literature for the identity of the species 
of Cylindrosporium under investigation, it was found that one form only 
has previously been reported upon Juglans. This species, C. nanum 
Cooke 1 2 ), has been reported from New Zealand. It has been impossible 
to secure specimens of C. nanum for comparison with the form upon 
English walnut, but the two are most certainly not identical, and, judging 
from the original description of C. nanum , are not to be referred to the 
same species. 
There has also been described from London, Canada, upon Car y a amara 1 
a form, Cylindrosporium caryogenum E. et E. 3 4 ) which is very similar 
morphologically to the form upon the leaves of English walnut. 
The two are, however, very different 4 ) in macroscopic characters. 
Because of this structural similarity and the possibility that the macroscopic 
1) IIlGGGINS, B. B., The perfect stage of Cylindrosporium on Prunus 
avium (Science N. S. 1913, 37, Nr. 956, 637—638). 
2) Cooke, M. C. (Grevillea, 14, 130). 
3) Ellis, J. B. and Everhart, B. M., New species of North American 
fungi (Proc. Acad. Sei. Philad. 1893, p. 168). 
4) Comparisons with the type material, N. A. F. 2451, collected Sept. 1889, have 
been made by Prof. G. F. Atkinson of Cornell University and Mrs. Flora W. Pat- 
