10 Nebraska Agricultural Exp. Station, Resea.rch Bui. 12 
state of maturity, seldom attains sufficient size to be worth 
harvesting. Stromata are rarely formed in large numbers. 
These symptoms, while most commonly found associated with 
drouth conditions, are by no means confined to trees under 
such conditions. Badly affected roots or trunk may induce 
the same symptoms. 
DESCRIPTION OF THE FUNGUS 
CONIDIAL STAGE 
As before stated, blisters appear during the late summer 
months upon the surface of the newly cankered areas. These 
blisters are caused by the formation of circular interwoven 
masses of mycelium just beneath the surface of the bark. 
Conidiophores arise from the surface of these stromata. They 
are short and usually more or less branched. Several conidia 
may be borne on the tip of each branch. Both conidiophores 
and conidia are nearly hj^aline. Gloyer^o jiot inaptly uses the 
term ''honey colored" in describing them. The conidia are 
oval, rather sharply pointed at the attached end, and measure 
about 5 by 8 microns, altho they are often smaller. The spores 
are set free by the layer of bark which covers the stromata 
being ruptured by the pressure of the conidiophores and spores 
beneath. 
Conidia may be produced during the latter part of the sea- 
son on one-year-old cankers. The same stromata may produce 
conidia the next spring and for several seasons thereafter. 
These subsequent crops of spores occur, however, only on 
cankers protected from direct sunlight. In many instances 
spores are not produced until the spring following the appear- 
ance of the canker. As before stated the stromata in many 
instances never produce spores at all, due to the death of the 
limb or tree cutting off the food and water supply of the 
fungus. During favorable seasons conidia are produced thru- 
out the growing season but as a rule under Nebraska condi- 
tions they occur most abundantly in the early spring during 
the months of April, May, and June, and to a less extent in 
September and October. 
Hasselbringii stated that he was unable to germinate the 
conidia, but Gloyer^o found them to be quite viable and that 
they germinated readily in distilled and well water, prune de- 
coction, and a 4 per cent sugar solution even after having 
been kept in the laboratory for three months. 
The writer found no difficulty in germinating conidia, 
when taken as soon as they matured, in water, and synthetic 
