LEAF-SPOT OF ALFALFA AND RED CLOVER. 21 
has not been necessary in the case of inoculations with Pseudopeziza 
trifolii, since the Pseuclopeziza leaf-spot has not occurred on any spe- 
cies of Trifolium about Madison during the time this work was in 
progress. The following host plants have been inoculated with pure 
cultures of both species of Pseudopeziza. 
HOST PLANTS INOCULATED. 
Medicago sativa with Pseuclopeziza medicaginis. — In seven or eight days, 
under greenhouse conditions, infections begin to show as minute brown spots 
scattered over the foliage. If infection is very abundant these leaves quickly 
die. If only four or five infections are scattered over each leaflet, apothecia 
begin to appear in about two weeks. For instance, one inoculation made on 
December 2, 1915, produced abundant apothecia on the spots by December 15. 
On December 20 spores discharged from apothecia on one of the leaves of this 
plant were cultured, and the fungus was recovered. An inoculation made on 
April 17, 1915, on plants in the field before the natural infection developed 
showed abundant spotting 11 days later.. The weather turned cold after this 
date and no fruiting was observed. 
Leaves of all ages are attacked. Leaves which have grown to full size 
appear to develop more abundant infections than leaves which are not full 
grown, but leaves which are yellow and weak do not seem to become infected 
as easily as those which are more vigorous. 
None of the infection experiments performed during three winters has failed 
to develop a greater or less amount of typical leaf-spot. 
Medicago sativa with Pseudopeziza trifolii. — Inoculation experiments have 
been repeatedly conducted parallel with those already cited on alfalfa, using 
plants of different ages. No infections visible to the naked eye have been 
produced. 
Medicago lupulina with Pseudopeziza medicaginis. — Plants of this host have 
never been very thrifty under greenhouse conditions, and therefore not a large 
number have beeen available for inoculation. In no case has any infection been 
obtained. Attempts to secure infection by setting Medicago lupulina plants 
in the garden among alfalfa plants which were heavily infected with Pseu- 
dopeziza medicaginis also failed to produce infection. 
Medicago lupulina with Pseudopeziza trifolii. — Only two inoculations have 
been tried. No infections resulted. 
Melilotus alba with Pseudopeziza medicaginis. — On March 28, 1915, several 
leaves of a vigorous sweet-clover plant were placed beneath fragments of a 
culture of Pseudopeziza medicaginis which was discharging spores. At the end 
of 24 hours the culture was placed over the entire plant, which was kept in a 
moist chamber 48 hours longer. After four days the leaves first inoculated 
showed minute brownish spots. These did not increase in size. After two 
weeks the portions of the leaves bearing the minute spots were embedded in 
paraffin and sectioned. In these sections the brown spots were found to 
consist of dead shrunken cells in which traces of mycelium could be found. 
But this mycelium appeared to be shrunken and dead and not advancing into 
the living cells of the host. From this, it appears possible that under favorable 
conditions P. medicaginis may be able to cause a very slight spotting of sweet- 
clover leaves. 
Trifolium- pratense with Pseudopeziza medicaginis. — Inoculations of red- 
clover plants in the greenhouse with pure cultures failed to produce any infec- 
tion. Red-clover plants grown in the garden in close proximity to badly dis- 
