Mar. 10, 19*3 Aluminum and Iron Compounds in Corn Plants 
807 
Marked increases in yield of corn plants have been obtained by various 
soil treatments. The investigations of Abbott, Conner, and Smalley (jr), 
Ruprecht (19), Hartwell and Pember (zo), and Mirasol (18) upon dif¬ 
ferent crops show that the addition of lime and phosphorus to the soil 
and to culture solutions has a beneficial action upon available toxic 
aluminum salts. 
Soil of the same type, as in the field shown in Plate 4, B, was used 
in the pot culture experiment illustrated in Plate 14, A. Note that 
limestone was beneficial in producing more vigorous stalks, whereas the 
addition of aluminum chlorid at the rate of 500 pounds per acre caused 
the plants to become very susceptible to the rootrots. The limestone 
treatment of the Hancock County soil, Plate 14, B, was ineffective, whereas 
acid phosphate produced better plants. The aluminum-chlorid treat¬ 
ment was more harmful than in the Shelby County soil. 
In 1918, an experiment conducted at Shelbyville, Ind., showed that 
the average yield of plants grown from nine healthy ears was increased 
35.7 per cent in a soil with a higher lime content, and the average yield 
of plants grown from five diseased ears grown in ear rows alternating 
with those from the healthy ears was increased 62.2 per cent. 
Results obtained by the Macon County (Illinois) Farm Bureau (21) 
in experiments on the control of corn rootrot by the use of fertilizers 
and limestone show that when “badly diseased” dent is planted the 
use of 3 tons of limestone per acre increased the yield of sound corn 
from 26.07 bushels to 44.43 bushels, or 70 per cent; from 40.13 bushels 
to 53.98 bushels, or 34 per cent; from 43.37 bushels to 52.90 bushels, 
or 21 per cent, in plots planted with different strains. The “disease- 
free” controls yielded at the rate of 49.69 bushels of sound com in the 
untreated plot and 60.36 bushels in the treated plot, giving a 21 per 
cent increase. It should be noted that the “disease-free” com yielded 
the highest in both the treated and untreated plots, yet the disease 
was most destructive in the untreated plots, all of which emphasizes 
the fact that the highest yields will be obtained when the best seed is 
planted in soil in the best state of fertility. 
Other results reported in various publications have been summarized 
by Slipher (20) and show increases in com yields due to the applications 
of lime, but no experiments have been noted which refer to the specific 
effects on the yield of plants growing from diseased seed. 
GENERAL APPEARANCE OF DISEASED PLANTS 
The symptoms associated with rootrots in dent have been described 
by Hoffer and Holbert (12), in sweetcom by Hoffer (jj), and later 
and in more detail by Holbert and Hoffer ( 13 ). These symptoms 
attributed to rootrots vary considerably because of the wide variations 
which occur in the type of growth of com plants. Some strains are 
hereditarily weaker than others, and, as has already been said, it is 
believed they possess marked differences in their absorption rates of 
available salts. No constantly uniform symptoms have been described 
in open-pollinated com because of these varying tendencies in the be¬ 
havior of these heterozygous individuals. 
Typical cases of individual plants affected by rootrots are shown in 
Plates 2, B, and 5, B. Plate 13, A, shows the disease as it occurred in a 
field in Shelby County in 1918. The stalks had grown to full size, but 
