Feb. a 4 , 1923 Early Vigor , Yield , and Diseases of Maize 
627 
SUMMARY 
1. Studies were conducted with diseased and apparently disease-free 
seedlings, transplanted from the germinator to the field. The disease- 
free seedlings made more rapid increases in height and circumference 
than the diseased seedlings during the first 25 days. The plants devel¬ 
oped from the disease-free seedlings gave a much higher yield of grain 
than the plants from diseased seedlings. 
2. Approximately 153,000 com plants were classified during their early 
growth stages as vigorous, semivigorous, or weak. Of this number, more 
than 6,000 were harvested individually and the plant yields determined. 
The populations were grown from both diseased and relatively disease- 
free seed. 
3. Early height and yield of com plants were found to be corre¬ 
lated directly. In most cases the coefficient of correlation was suffi¬ 
ciently large to be significant. 
4. Plants strong and vigorous in their early stages of growth produced 
a larger percentage of good-sized ears, and therefore higher yields of 
grain, and matured their grain somewhat earlier than the weaker ones, 
regardless of height at harvest time. 
5. Plants weak in their early stages of growth usually produced nub¬ 
bins only, or were barren. 
6. Yields were recorded on the basis of marketable and unmarketable 
corn, the latter consisting of small nubbins, rotted ears, and light chaffy 
ears. 
7. Nearly disease-free and moderately diseased seed were compared 
under different conditions in a number of experiments at Bloomington, 
Urbana, and elsewhere in Illinois. 
8. Com grown from seed not infected with the root and stalk rot 
pathogenes or not susceptible to the root and stalk rots had a higher 
percentage of strong, vigorous plants, a lower percentage of weak plants, 
and produced higher total yields and higher yields of marketable corn 
than com grown under comparable conditions from infected or susceptible 
seed. 
9. Com populations grown from seed infected with one or more of the 
root and stalk rot pathogenes or susceptible to the root and stalk rots 
produced a much lower yield of sound, marketable com and a larger 
percentage of nubbins, rotted ears, and light chaffy ears than com grown 
from seed relatively free from and resistant to infections. 
10. Corn earworms seem to show little preference between com from 
diseased or nearly disease-free seed within a variety, but the total injury 
on the latter is much less because the worm injury is not followed by 
ear rots to the extent it is on the former. 
11. Relatively disease-free seed ears selected from badly rotted plants 
proved to be inferior to relatively disease-free seed ears selected from 
apparently disease-free plants, especially when the comparisons were 
made on infested soil. 
12. Not all lots of seed com are suitable for selecting disease-free seed 
com. Some types of com are so susceptible to disease that seed which 
passes a good test on the germinator proves very susceptible when 
planted in infested soil. 
13. Com resistant to root and stalk rots is also resistant to ear rots. 
