COE SE LS el CN ES SIN to oe ea ESS FS ee a 
Notes on a parasitic Gnomonia* 
CLAUDE WILBUR EDGERTON 
In the month of July, 1906, while looking for the presence of 
anthracnose on the canes of the blackberry, Rubus nigrobaccus, in 
the vicinity of Ithaca, New York, I found in the garden of Pro- 
fessor Whetsel a few canes that were affected with a pyrenomycete, 
a member of the genus Gromonia. Thinking that this might be 
the perfect stage of the anthracnose, I gathered material and made 
a study of it. The result of the study showed that the fungus 
had no connection with the Gloeosporium, yet from the fact that 
it seems to be undescribed in this country and. may occasionally 
cause disease of the blackberry canes, it seems well to make a 
note of it with drawings and photographs. 
The disease evidently made its appearance in the spring, as 
Spots were noticed on the canes at pruning time. But no effect 
on the canes had been noticed at that time. Leaves developed 
normally, blossoms appeared on the stems, and the fruit set, so 
that the plants had the appearance of being perfectly healthy. It 
was not until the fruit was a little over half grown that the effect 
of the disease was noticed. Very suddenly, the leaves and the 
fruit above the spots wilted and dried up. The effect on the plant 
seemed to be that of girdling. The appearance of the canes 
was very similar to the cane blight of raspberries caused by a 
species of Coniothyrium, as described by Stewart and Eustace. 
The plants were in this condition when they were first observed 
by the writer. The spots at this time were very evident, being 
two to five inches in length and completely encircling the stems, 
somewhat lighter in color than the healthy regions and possessing 
a dry, dead appearance. 
An examination of the spots showed the presence of numerous 
black perithecial beaks, which appeared to the naked eye as small 
black setae, protruding through the dead cortex (FIG. I). The 
main body of the perithecium was imbedded in the host tissue. 
* Contribution from the Department of Botany, Cornell University, No. 123. 
+ New York Experiment Station Bulletin no. 226, Geneva, N. 
* 
