8 o8 
Journal of Agricultural Research 
Vol. XXIII, No. xo 
shortly after the ears began to develop the roots became severely rotted 
and many of the stalks fell over. A similar condition of a field of S to well’s 
Evergreen Sweetcom is shown in Plate 13, B. Here, too, many of the 
stalks grew to a good size but after tasseling became badly rootrotted. 
More of the stalks in this field were of stunted growth than in the Shelby 
County field, however. 
These two cases are characteristic of the occurrence of the rootrots in 
soils high in organic matter with abundant nitrates but with little calcium 
and available phosphorus. The nitrates in these soils favor abundant 
vegetative growth of the plants. The plants under these conditions 
show discolorations of the nodal tissues very early in their growth, and 
when they reach the tassel and ear stage of development the nodal 
tissues frequently are much disintegrated. This disintegration of the 
nodal tissues results in broken shanks and a weakened root system. 
The translocation of foods to the roots is retarded and they cease func¬ 
tioning, as shown in Plate 8, B. 
The general condition of the plants shown in Plate 4, A, is a very 
common one in large areas in the Corn Belt. The plants are stunted 
in their growth, and when they are cut longitudinally and examined 
internally the nodal discolorations will be found in abundance in the 
basal portion. The soils in these fields were distinctly acid, relatively 
low in organic matter, and deficient in calcium and available phosphorus. 
After the application of 3 tons of limestone to the soil in the field shown 
in Plate 4, A, the plants grew very well the following season, 1920. 
The plants in the treated plots were resistant to the rootrots which 
affected those in the untreated plots. 
The plants more resistant to the rootrots grow in soils containing 
abundant nitrates and adequate calcium and available phosphorus. 
Calcium carbonate was found to be harmful when applied alone to the 
soil in the field shown in Plate 15, A. In this field acid phosphate gave 
the best results. The plants in the calcium-carbonate plot were more 
severely affected by the nodal accumulations of metals than those in 
the control plot. 
Reference has already been made to the results of the Macon County 
Farm Bureau experiments (21). The rootrot phenomena which develop 
in plants in that locality are very similar to those shown in Plates 4, B, 
and 13, B. By the addition of lime and phosphate to this type of soil 
greater resistance to these rootrots is developed in the corn plants. 
It seems from these observations that the quantitative calcium- 
nitrogen relations which exist in the soils are probably important in 
connection with the development of the symptoms of rootrots. Whether 
or not the high nitrogen influences the growth of the plants so that they 
become susceptible to the rootrots or whether the available metals, 
which are more abundant under the conditions of high nitrogen and low 
calcium in the soils, determine the susceptibility of the plants to the root¬ 
rots has not been learned. It is probably best to assume for the present 
that no one of these factors can be fully interpreted independently of 
the others, so that due consideration must be given to all of them and 
their interrelations established. 
No detailed consideration will be given to the fertilizer experiments 
conducted as a part of the rootrot investigations in this paper. The 
results of these experiments will be published elsewhere. It is desired 
to refer only to the soil conditions in general where the rootrots prevail 
