-144- . 
Treatment 
y 
Total ears 
Conditions of ears — 
Clean 
Grades 
1 and 2 
Infested 
Infested 
but salable 
Number 
Percent 
Percent 
Percent 
Percent 
Derris 
2,124 
95.1 
90.0 
4.9 
57.2 
Nicotine tannate 
2,447 
92.1 
88.4 
7.9 
53.0 
Pheno thiamine 
2,232 
89,9 
78.8 
10.1.... . 
48.4 
Check 
1,993 
77.7 
70.4. 
22.3 
45.7 
y 
Four plots totaling l/8 acre for each treatment. 
On each farm Span Cross 2, • the earliest variety of yellow sweet corn 
to mature was tested. The crop was harvested as rapidly as possible, 
which allowed a comparatively short -time for the infestation of the ears 
and enabled the check plots to show a much better record than the relative 
infestation warranted. Practically every stalk in the check plots was 
infested and many contained 6 to 8' borers and were seriously weakened, 
while comparatively few stalks in the sprayed plots showed the presence 
of borers. In January 1937 Questel reported that derris spray (4 lb. per 
100 gal., 0.0192 percent rotenone) and derris dust (l percent rotenone) 
were effective in reducing the population of second-generation borers in- 
festing dahlias at ililford, Conn. The station in 1938 reported the re- 
sults with derris spray, as follows: In the derris plot, 5 percent of 
the sprayed plots and 12 percent of the checks were damaged 
by borers. In the treated plots the infested stalks were not often ser- 
iously damaged and for the most part, contained only one and two small, 
young-stage larvae, whereas in the checks the stalks were badly riddled 
often contained from five to eight mature borers, and many stalks had 
broken down before the ears had fully matured. The loss of vitality to 
the plants caused by even a light or moderate infestation is clearly re- 
flected in the yield records as shown by the following table: 
Infestation 
Increase en 
t 
reat 
ed 
over 
untreated plots 
Material 
Total ears 
per acre 
Uninfeste I ears 
per acre 
Percent 
Numbe r 
Numt r 
Dual-fixed nicotine 
(dust) 
30 
225 
1,562 
Derris (spray) 
5 
1,692 
2,052 
