Peb. 34,1933 
Early Vigor, Yield, and Rot Diseases of Maize 
599 
than com grown from nearly disease-free seed. Much of this com of 
inferior quality would be left in the field unharvested by most farmers. 
Many farmers who might gather such com from the field probably would 
either sort it out when dumping the com at the crib or when shelling it 
for market. At any rate, small nubbins, rotted ears, and chaffy ears 
represent com of low grade and low selling value. 
In view of these facts it was deemed advisable, beginning in 1920, to 
report separate yields of marketable and unmarketable com. Plates 2, 
3, and 4 illustrate the kinds of com that were classified as marketable and 
unmarketable. There are occasional ears about whose classification there 
might be some question; but, on the whole, personal judgment changes 
but little within a given experiment, and errors due to personal factors 
are comparatively few when a large number of experiments are concerned. 
Although this procedure is imperfect, it gives a more accurate index to 
the value of any yield of com than total yield alone. When considering 
yield under actual farm conditions, quality should be as important as 
quantity, a fact forcibly emphasized in the 1921 data. 
In presenting data from experiments conducted in 1920 and 1921, it 
seemed desirable to report yields in terms of percentages of increased 
yield of nearly disease-free over the moderately diseased seed, inasmuch 
as the moderately diseased seed used was representative of the majority 
of seed ears used by the farmers supplying the seed for the experiments. 
The yields from these different lots of moderately diseased seed were 
higher than the average com yield of the counties in which the experiments 
were conducted. On the Agronomy South Farm of the Illinois Agricul¬ 
tural Experiment Station at Urbana, these lots of moderately diseased 
seed compared favorably in yield with the standard varieties. The nearly 
disease-free seed lots used in the experiments (1920 and 1921) were prac¬ 
tically free from any of the root and stalk rot pathogenes, as evidenced by 
repeated laboratory determinations, and represented the best seed ears 
available in the open fertilized seed stocks of the Com Belt. 
Table XV.— Influence of moderately diseased and nearly disease-free seed on early vigor 
and yield of marketable corn. Reid Yellow Dent (Macon County strain) grown on 
infested soil of medium fertility, at Bloomington, III., in IQ20 
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. 
Percentage of nubbins (by count)... 
Percentage of rotted ears (by count). 
Percentage of chaffy ears (by count). 
Moder¬ 
ately dis¬ 
eased 
Nearly 
disease- 
free 
In favor of disease- 
free seed. 
com¬ 
posite. 
com¬ 
posite. 
Increase. 
Decrease. 
727 
846 
Percent. 
Percent. 
75-8 
88.1 
16. 2 
29. 2 
45-3 
55-2 
12.3 
6-3 
48.8 
49.8 
63 - S 
27-5 
33-7 
54-6 
62.0 
23*3 
11. 6 
50.2 
10. 7 
3*9 
63-5 
26. 0 
7-7 
70.4 
Table XV gives data showing the influence of seed infection on early 
vigor and subsequent yield and quality. The increased percentage of 
26551—23-2 
