406 
Journal of Agricultural Research 
Vol. XXVI, No. 9 
DEATH RATE OF ADJACENT PLANTS 
In order to determine if the rate of progress was the same in all direc¬ 
tions from the center, the progressive spread was measured in nine 
circular spots during the summer of 1922. The spots, when selected on 
June 23, were almost perfect circles, and on that date three of them 
were approximately 5 meters in diameter, three others were about 
3 meters in diameter, and the other three were i l /> meters in diameter. 
About each of these spots two circles were described, 15 and 35 cm. 
Fig. i.—G raphical representation of the death rate of alfalfa plants in rootrot circles of different diameters. 
The solid fines indicate the number of dead “B” plants, and the dotted lines the number of dead “C” 
plants, or those on the outer circles. 
outside the ring of dead plants. On the first of these circles plants were 
selected and tagged as “B” plants, 90 in the 5-meter spots, 60 in the 
3-meter spots, and 30 in the meter and a half spots. In each case the 
plants were spaced at approximately equal distances. In the outer 
circle 45, 30, and 15 plants were similarly selected and tagged as “C” 
plants. Observations were made each day on the 15 days following, 
