140 Report or THE DEPARTMENT OF BOTANY OF THE 
THE SPOROTRICHUM BUD-ROT OF CARNATIONS 
AND THE SILVER TOP OF JUNE GRASS.* 
F.C. STEWART anv H. E. HODGKISS. 
SUMMARY. 
The carnation bud-rot herein described is identical with the dis- 
ease discussed by Heald and Wolcott tn Nebraska Experiment Sta- 
tion Bulletin No. 103. It is known to occur in several greenhouses 
in New York, Illinois and Nebraska, but probably it is not of great 
economic importance. 
Silver top is a widespread grass trouble well known to ento- 
mologists, but not thoroughly understood. The flower panicles 
wither before they have become fully expanded. In New York, 
June grass (Poa pratensis) is very generally affected with 
silver top. 
Carnations affected with bud-rot are invariably infested with a 
certain fungus almost constantly associated with a particular species 
of mite. The same fungus and mite are frequently found similarly 
associated on June grass culms affected with silver top. It has 
been proven that the fungus, by itself, is capable of producing bud- 
rot of carnations. The relation of the mite to the carnation disease 
is not entirely clear. ‘Probably it acts as a carrier of the fungus. 
The relation of the fungus and mite to the silver top of grass has 
not been investigated. 
Although the fungus of carnation bud-rot and the fungus on June 
erass have received different names (the former S poro- 
trichum anthophilum. Pk. and,‘the , latter,, pornos 
trichum poe Pk.), laboratory studies and inoculation experi- 
ments show them to be oneand the same species. S. po@, being 
the older of the two names, must be given precedence. 
The mite is the same as the one to which Wolcott gave the name 
Pediculoides dianthophilus ; but it has been identi- 
fied positively as Pediculopsis graminum Reut. which, 
according to Reuter, is the chief agent in the production of silver 
top of grasses in Finland. 
*A reprint of Technical Bulletin No. 7. 
