222 REPORT OF THE DEPARTMENT OF BOTANY OF THE 
curved spores measuring 5-7 x 3.5-4 4; and a Fusarium with hya- 
line, curved spores usually 3-septate and measuring 35-53 X 5-7 » 
Both species were whitish, but the Dendrodochium was in little 
heaps which often showed a tinge of pink, whereas the Fusarium ~ 
was more diffuse in habit and with a tendency to become bluish 
green.®? Although no inoculation experiments have been made we 
are of the opinion that the Dendrodochium and Fusarium are only 
saprophytes and that Colletotrichum trifolu is the cause of black 
crown. One reason for this opinion is the following observation: 
On September 26, 1907, 14 pieces of blackened woody tissue from 
as many different alfalfa crowns were placed in a moist chamber. 
From each piece the bark had been completely removed exposing 
a clean, smooth surface of blackened wood. At the end of 48 
hours a microscopic examination was made. ‘Twelve of the pieces 
were thickly covered with acervult of Colletotrichum trifolu. Both 
spores and sete were produced in abundance. There was little or 
no superficial mycelium —the Colletotrichum acervuli were seated 
directly on the cut surface of blackened wood covering it almost 
completely. On some of the pieces Dendrodochium and Fusarium 
also developed. 
From our limited observations on this Colletotrichum we should 
say that the greater part of the damage done to alfalfa results from 
its attack on the crown of the plant and that the stem spots are 
1elatively unimportant. We have never seen the leaves affected. The 
bad reputation of this fungus in Tennessee makes it of consider- 
able interest to New York farmers. To what extent it occurs in 
New York clover fields we are unable to say, no investigation of 
clover fields having been made. 
ROOT-ROT AND DAMPING OFF. 
(Rhizoctoma sp. and Pythium de baryanum Hesse.) 
In various parts of Europe there is a destructive root-rot of al- 
falfa caused by Rhizoctonia medicaginis DC. The disease mani- 
fests itself in the form of circular dead spots in the field. The roots 
of affected plants are thickly covered with a violet-colored myce- 
lium. Fortunately, this fungus is rare in America. No record of 
its occurrence in New York is known to us and we have never seen 
* Grown in pure culture on plugs of sugar beet this Fusarium is bluish 
green very much like Penicillium glaucum. On unneutralized alfalfa agar it 
is cream colored. 
