The usual relationships of infection to husk coverage, determined for each 
disease in previous tabulations by averaging the percentages of open and covered in- 
fected ears, and the differences between them, for the years during which each was 
observed, are brought together in Table 17 and are shown graphically in Figure 2. 
With this comparison as a basis, the 8 ear diseases can be considered to fall in 3 
rather well defined groups. 
The first of these, which includes smut, Fusarium rot, and Penicillium rot, 
may be considered to be favored to a considerable degree by imperfect husk coverage. 
Table 17.-= Summary of the relation of individual rots to 
husk coverage, 1931-1935. 
“| Average percent of | Average excess 
Type of rot rotted ears of open, 
a ___! _ Open _! Covered in percent 
Smut BU el. | Saw 80.2 
Fusarium 68.8 | Slee 37.6 
Penicillium 61.8 | 38.2 2506 
Rhizopus ' 54,6 45.4 Gas 
Aspergillus 45.5 | 04.9 - 9,0 
Basisporium 4502 54.8 - 9.6 
Gibberella 43,1 Jeo - 13.7 
Diplodia 58.8 61.2 ~ 220% oe 
The second group, which includes Rhizopus, Aspergillus, and Basisporium rot, probably 
depends very little upon imperfect coverage for the opportunity to infect but is in- 
fluenced, as suggested in Tables 11, 12, and 16, to a large extent oy environmental 
factors or by differences in development or condition of the corn plant itself. 
The third group, in which are included Diplodia and G bberella ear rot, 
Menoard to exhibit a marked negative correlation between abundance of infection and 
imperfect husk coverage, since in each case a considerably greater proportion of the 
infected ears were well covered by husks, The significance of this is not apparent 
[16] 
