932 
Journal of A griculfural Research voi. xxvn, no. 12 
It will be noted that unusually severe infections were obtained in all 
13 varieties on the spring-inoculated soil. On the soil inoculated in 
the fall a number of the varieties showed considerable infection. In this 
latter series it is of especial interest to note that two varieties, Haynes 
Bluestem and Marquis, showed a moderately high degree of seedling 
injury but low percentages of infection in the threshed grain. Such 
variations in these or other varieties were not evident on the soil inocu¬ 
lated at sowing time in spring. This may have been because of the 
unusually severe infection, as practically all the plants grown on the soil 
inoculated at the time of sowing were badly stunted and deformed and 
produced but few normal kernels (PI. 1, E). Infection was much less 
severe on the soil inoculated in the fall, some of the varieties even com¬ 
paring favorably in vigor, and apparently in yield, with those grown in 
the uninoculated control rows. 
A similar experiment with fewer varieties was conducted at Madison, 
Wis., in 1921, with similar results. In one plat the galls were placed in 
the soil on October 7, 1920, and in another plat on April 7 the following 
spring, at which time four varieties of spring wheat were sown in both 
plats and also in an adjacent uninoculated control plat. No infections 
occurred in the latter. The data on seedling injury in the inoculated 
plat were obtained as before by observing 300 plants in each plat. The 
amount of infection is shown in Table VI. 
Table VI .—Percentage of plants showing seedling injury and percentages by volume of 
galls in the threshed grain from four varieties of spring wheat grown on soil inoculated 
with galls in the fall and on soil inoculated at time of sowing at Madison , Wis., in IQ 2 I 
Seedling injury on— 
Percentage by 
volume of galls in 
threshed grain. 
Variety. 
Soil inoc¬ 
ulated 
in the 
fall. 
Soil inoc¬ 
ulated 
in the 
spring. 
Soil inoc¬ 
ulated 
in the 
fall. 
Soil inoc¬ 
ulated 
in the 
spring. 
Marquis .. ..... 
Per cent . 
5 
Per cent. 
66 
Trace. 
71 
Prelude .... 
10 
72 
10 
95 
Huron ... 
2 
80 
6 
80 
Unnamed hybrid.. 
6 
84 
4 
70 
Average. 
6 
76 
5 
79 
It seems evident that although the nematodes can overwinter to some 
extent in the soil in Wisconsin, the only important source of infection 
of spring wheat would be infested seed. The use of such seed results in 
an almost worthless crop. This experiment with spring-wheat varieties 
was repeated in 1922 at Madison with similar results. The stand and 
yield of the wheat grown on the soil inoculated in the spring were prac¬ 
tically negligible, while those of the wheat sown in soil inoculated the 
previous fall were quite good. 
Rye was included in the latter experiment and, although the soil 
inoculated in the spring did not cause as severe an infection as in the 
case of the wheat, yet the yield was considerably reduced. The rye 
grown on fall-inoculated soil was not appreciably injured. The results 
are given in Table VII. 
