-145- 
In every case the treated plots showed an increased total yield over 
the checks. On the basis of uninfested ears, the difference was even more 
pronoun ced. Even in comparatively light infestations, as in the derris 
plots, an advantage of more than 2,000 ears per acre represented a consid- 
erable profit to the grower. A more significant index of the value of the 
treatments is the relative proportion of Grade 1 corn harvested from the 
experimental plots as shown in the following table: 
- 
Total 
yield 
Material 
Uninfested 
plots 
Grade 1 ears 
in plots 
Dusted 
Check 
Dusted 
Check 
Dual-fixed nicotine 
Nicotine tannate 
Derris 
Percent 
92,8 
97.6 
98.3 
Percent 
70,0 
94,4 
94.9 
Pe re ent 
76 
72 
88 
Percent 
48 
60 
81 
The field containing the derris plots was heavily fertilized. The 
corn made excessive stalk growth and many of the ears did not fully develop 
and were graded as culls. Since the total yield in this field, however, 
was at the rate of 24,000 ears per acre, even the small difference of 7 
percent represented an increase of 1,680 ears, Derris spray increased the 
uninfested ears per acre by 2,052, and the grade-1 ears by 1/680, 
The same station in 1939 reported the results of field tests with 
three dusts — dual-fixed nicotine, cube-vatsol, and a commercial rotenone — 
conducted in a commercial planting in Hampden County, and with four sprays, 
including ground derris, cube, and two of commercial rotenone. The sprays 
and dusts were applied at 5-day intervals from June 10 to June 25, the 
"~TlTr"st~ application being based on the general appearance of the young larvae, 
The sprays gave satisfactory protection and the dusts fair commercial con- 
trol on the basis of the borer-free ears harvested. The real value of the 
insecticidal treatments, however, is indicated by the relative proportion 
of the total yield that was of marketable grade. In the dusted plots from 
62 to 65 percent of the crop was borer-free and 50 to 56 percent of mar- 
ketable grade j in the sprayed plots from 75 to 80 percent of the total 
yield was borer -free and from 57 to 60 percent was marketable; while in 
the unsprayed plots only 16 percent of the crop was boror-froe and less 
than 12 percent of the ears fit for market. 
The Connecticut Agricultural Experiment Station (78) in 1938 reported 
that trials of sprays devised by the United States Department of Agricul- 
ture for control of the European corn borer in Connecticut were again suc- 
cessful. One spray contained pure ground cube root at the rate of 2 pounds 
in 50 gallons of water with and without spreaders. It was applied four 
times, on June 9, 15, 22, and 26 for the first generation, and resulted in 
75 percent of the ears being borer free. Untreated plants produced 37 per- 
cent of borer-free ears. Dual-fixed-nicotine dust applied on the same 
dates was not so effective as the sprays. Second-generation sprays were 
applied on August 5, 9, 14, 20, and 27. A spreader increased the percent- 
age of borer-free ears (64,8^ as compared with cube without a spreader 
(57,3), and the untreated chock (9,7). A pyrethrum spray was not effective. 
