604 
Journal of Agricultural Research 
V6I. XXm, No. 8 
Table XX.— Influence of moderately diseased and nearly disease-free seed on early vigor 
and yield of marketable corn of Reid Yellow Dent on heavily infested soil , limed and 
phospkated, at Urbana, III., in 1920 
Points considered. 
Number of plants in experiment. 
Early vigor: 
Percentage of kernels producing plants. 
Percentage of kernels producing vigorous 
plants. 
Percentage of kernels producing weak plants. 
Yield: 
Total acre yield (in bushels). 
Acre yield of marketable com (in bushels).... 
Moder¬ 
ately dis¬ 
eased 
Nearly 
disease- 
free 
In favor of disease- 
free seed. 
com¬ 
posite. 
com¬ 
posite. 
Increase. 
Decrease. 
2,096 
2.338 
Per cent. 
Per cent. 
74 * 5 
83- 4 
XI. 9 
1-7 
2 . 6 
52-9 
59*3 
59*2 
O. 2 
39*2 
47*9 
22. 2 
3 2 * 4 
4 i .3 
27*5 
DATA OBTAINED IN 1921 
The season of 1921 was different in many respects from the seasons of 
the previous three years. As a result of fungus injury following the 
unusually heavy attacks of the corn earworm (Chloridea obsoleta Fab.) 
during the warm, moist weather of the late summer and early fall, there 
was a very high percentage of rotted corn throughout the Com Belt. In 
view of these facts the 1921 data relative to marketable and unmarketable 
com in the yields from moderately diseased and nearly disease-free seed 
are of extraordinary significance. These data not only give further evi¬ 
dence on the important relations existing between seed infection, reduced 
early vigor, and reduced yields of sound com, but show clearly that corn 
grown from seed infected with the root and stalk rot pathogenes, or seed 
susceptible to the root and stalk rots, is likely to be much more susceptible 
to fungi causing ear rots than com grown from seed relatively free from 
these pathogenes. In most cases the different lots of com were infested 
to approximately the same extent with earworms, but there was a vast 
difference in the degree to which the different lots were injured by the 
fungi following the attack of earworms. The principal fungi concerned 
with ear rots were Diplodia zeae and Fusarium spp. 
The data presented in Tables XXI to XXV were secured from plant¬ 
ings on the no-treatment plots in a series of fertilizer experiments. These 
soil plots were not all equally fertile, but the soil variation within each 
plot probably was very slight. Consequently, comparisons should be 
made between the moderately diseased and nearly disease-free on each 
plot. The plantings on the various no-treatment plots were replications 
in which the same two seed composites were used throughout the four 
times of planting. The results are reported in Tables XXI to XXV and 
graphically presented in figures 9 to 13. 
