Feb. *4,1933 
Early Vigor , Yield, and Rot Diseases of Maize 
595 
period of four years in which alternate plots were planted with relatively 
disease-free and diseased Seed. Where field stands and other factors 
were reasonably comparable, there has been a reduction in the percentage 
of vigorous plants, as classified 25 to 35 days after planting, as well as 
a reduction in final acre yield in bushels, although the relation varied 
from year to year, depending on seasonal conditions. These data are 
summarized in Table 10. The 1920 data are presented in more detail 
and discussed later in this paper. A part of the 1921 data is presented 
in both detailed and summarized forms to show more clearly the methods 
used in the investigations on which this paper is based. 
Table X. —Summary of data showing influence of seed infection on early vigor and 
yield of corn grown from relatively disease-free and diseased seed, at Bloomington, III., 
in igi8 , 1919, 1920, and 1921 
Year. 
Number 
of experi¬ 
ments. 
Total 
number 
of plants 
classified. 
Average re¬ 
duction in 
percentage 
of vigorous 
plants. 
Average in- 
creasein 
percentage 
of weak 
plants. 
Average de¬ 
crease in 
acre yield. 
1918. 
7 
22,479 
9-7 
• 4* 8 
‘ 'Bushels. 
14.4 
1919 . 
7 
29, 013 
9 » 3 i 8 
13-3 
6.3 
12. p 
1920.. 
8 
15-4 
4.2 
8.6 
1921. 
4 
6 ,134 
22. 6 
4.9 
9.2 
relationJof early vigor and yield as influenced by pathologic 
CONDITION OF MOTHER PLANT 
In the fall of 1917, attractive ears were selected from vigorous and*ap- 
parently healthy plants and from plants whose roots and stalks were 
rotted. The seed was planted the following spring in ear rows, the seed 
from apparently healthy plants being alternated with the seed from 
diseased plants. Similiar experiments were conducted during the follow¬ 
ing two years. The data from these experiments are given in Table XI. 
Seed ears selected from plants whose roots and stems are badly rotted 
may or may not be infected with the rot pathogenes. In many cases 
they are not infected to such an extent that the infection can be detected 
by a careful germination test. But when these ears are used for seed 
they usually produce plants that are very susceptible to the root and 
stalk rots. 
Table XI. —Early vigor and yield as influenced by the pathologic condition of mother 
plants from*which seedtwas selected. The table shows reduced vigor and reduced yield in 
plants grown from seed selected from diseased plants , at Bloomington , III. 
Year. 
Variety. 
Number 
of plants. 
Reduction 
in stand. 
Reduction 
in vigor-. 
ous plants. 
Increase 
in w^ak 
plants. 
Decrease 
in acre 
yield. 
Reduction 
in yield. 
1918 
Reid Yellow Dent. 
S. * 4 ° 
Per cent. 
IO. 9 
Per cent . 
4*4 
Per cent. 
I. 2 
Bushels. 
7-3 
Percent. 
IO. 9 
1918 
Funk 90-Day... 
6,617 
•5 
14. 1 
2.8 
11. 4 
16.3 
1919 
.do. 
2 , O 9 O 
2 . I 
IS -4 
1-3 
6. 8 
9.2 
1919 
927 
*•5 
■ 5-5 
1. 6 
2-5 
4 * 3 
1920 
Reid Yellow Dent. 
I »357 
5-2 
9 - 5 
1. o 
12.4 
16.5 
1920 
3,144 
. I 
4-7 
1. 2 
6. 0 
7-5 
