LEAF-SPOT OF ALFALFA AND RED CLOVER. 33 
on May 10 no trace of Pseudopeziza had appeared. The plants were then 10 
to 12 inches tall, very vigorous, and in a dense mat apparently favorable for 
the development of the fungus. At the end of this experiment the plat was 
inoculated with Pseudopeziza from overwintered leaves and was quickly over- 
Tun with the disease, showing that the greenhouse conditions were favorable 
for its development. 
(2) On January 27, 1917, a plat about 4 feet square was sown in the garden 
greenhouse with unsterilized Kansas-grown alfalfa seed. This plat developed 
normally without leaf-spot until May 5, when the disease was present in the 
field outside. 
(3) On February 16, 1917, a plat 2 by 3 feet was sown in a garden green- 
house with sterilized alfalfa seed 3 years old. This plat likewise developed 
normally with no leaf-spot until May 10, at which date leaf-spot was abundant 
outside the greenhouse. 
Several other- plats were started and developed in the green- 
house without leaf-spot, like those referred to above, but owing to 
insect injury the conditions were not as favorable for the develop- 
ment of the disease as those described. In fact, all greenhouse plats 
started from seed, whether sterilized, unsterilized, or even treated 
with spores before sowing, have developed without the appearance 
of leaf-spot until the disease occurred abundantly in an alfalfa 
field close outside the greenhouse. 
Field plats.—In the selection of locations for plats three conditions 
were sought: (1) Remoteness from large areas of growing alfalfa; 
(2) the greatest possible distance from farms where alfalfa has been 
grown; and (3) accessibility, so that a visit to the plat would be 
possible. The second condition was very difficult to secure. Small 
plats of alfalfa are surprisingly abundant even in localities where it is 
not grown as a farm crop. In consequence of this fact, only one of 
the eight plats started in 1915 was found upon examination to be 
sufficiently remote to give results of value. 
In 1915 the assistance of the States Relations Service secured the 
cooperation of several agricultural county agents whose intimate 
knowledge of local conditions made possible the selection of a larger 
number of suitable locations. To these men the writer is indebted 
for any degree of success that was attained in these experiments. 
The seed which had been sterilized superficially was furnished to 
the agricultural county agents, who allotted it to the men on whose 
farms the plats were to be located. In the autumn all the plats 
were visited except the one at Bruce, 8. Dak., which was under the 
observation of Dr. A. G. Johnson, and the presence or absence of 
leaf-spot was determined. In a number of cases alfalfa was found 
growing nearer the plat than was previously supposed. The results 
noted on such plats—always an abundance of leaf-spot—are excluded 
from the summary in Table VIII. However, if, as sometimes oc- 
curred, the near-by plants were very few in number and no other 
