° 
yt 
the annual variation in prevalence, open ears were infected to a significantly great- 
er extent than covered ears and, conversely, covered ears were free of rot infection 
to a significantly greater extent than open ears. Averages for the 3 years show a 
difference of 10.2 percent between open and covered ears, the open ears exceeding the 
covered ears to that extent in number of rotted ears, and the covered ears exceeding 
the open ears to the same extent in number of sound ears, 
In the analysis presented in Table 6, in which the diseased ears found an- 
nually are assorted into open and closed groups and the number in each group is ex- 
pressed as a percentage of the total, the difference between the percentages of open 
Table 6,-= Prevalence of husk coverage types among rotted corn ears, 
1933-1955. 
i a te ee 
eee 
EE ee oe ene 
Excess of 
Rotted ears } Number of ears open, in 
Percent of ears 
Year | examined Open i Covered | Open _| Covered | percent 
| 
1933 | 4,183 2,801 1,382 ora) 33.0 34,0 
1934 12,009 Py Od. 5,208 560 42.5 15.0 
1935 | 4,462 2,686 | 1,776 60.2 39.8 20.4 
Average he hers 61.6 38.4 | 2502 
oe ee ee ee me . i —e ee ee 
and closed infected ears each year shows consistently a marked preponderance of open 
rotted ears over covered rotted ears. This preponderance averages 43.2 percent for 
the 5-year period covered by the data. 
FIELD PREVALENCE OF SPECIFIC EAR ROTS 
The field prevalence of 8 of the more common and presumably more important 
corn ear diseases was determined annually during the 5 years, 1931-1935, by examining 
each year a large number of cars in a considerable number of fields. While the 
amount of data taken varied to some extent from year to year, as shown in Table 7, 
297 fields were visited and 57,395 ears were examined during the period, and except 
[7] 
