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The mechanical effect of the clay dust on the larvae was fatal, al- 
though it allowed them to travel farther than the dual-fixed nicotine or 
the derris dusts. The dual-fixed nicotine apparently acted as an egg 
destroyer, but in this particular case the egg .mass had been placed face 
downward on the dusted surface. In a season when rainfall is not exces- 
sive a dust such as dual-fixed nicotine, applied just before hatching and 
kept on the plant during' the hatching period, should give good results, 
Questal in September 1937, in a typewritten report to the Division of 
Cereal and Forage Insect Investigations, stated that early market sweet 
corn was completely tolerant to derris spray and derris dust. In another 
typewritten report to the Division, he said that derris spray (i lb. per 
100 gal.), containing 0.0235 percent of rotenone, gave high control on 
Golden Cross Bantam corn at Maumoe, Ohio, in 1937. Derris dust (0.98 per- 
cent rotenone; plus sodium butyl hydroxy phenylbenzenesulfonate 1:3,000 
was equal to a dust of dual-fixed nicotine but inferior to dorris spray. 
The plants were completely tolerant to both derris sprays and dusts. In 
1937 Questel stated in a similar report that various fluorine compounds 
compared favorably with derris as a spray on early sweet corn in the vicin- 
ity of Toledo, Ohio. In a similar report in 1938, he said that ground 
derris was outstanding among the sprays used at Toledo. Very good control 
was obtained, as well as complete freedom from spray injury to the sweet 
corn plant. "When applied by hand with a single nozzle, this spray appeared 
to be satisfactory for use in the Lake States. The labor cost of applic - 
tion by this method is high, however, and types of booms tested, although 
reducing the labor cost, did not allow sufficient quantities of the spray 
to enter the whorl of the corn plant, therefore the control was lessened. 
The derris powder was used at the rate of 4 pounds per 100 gallons of 
water and contained 4 percent of rotenone. Derris dust (1 percent rote- 
none) was less effective. Ground derris (four applications at 5-day inter- 
vals starting with first hatching) was outstanding among the sprays tested 
in 1938 and provided a very satisfactory control when applied with a hand 
nozzle. 
Questel ( 541 ) in 1938 again reported that ground derris (4 lb. per 100 
gal. of water) was the outstanding spray used in the Lake States. V. r ith 
this spray, 97.8 percent of the No. 1 ears in the treated plots were borer- 
free, as compared with 68,4 percent in the nontreated plots, and the 
borer population in the treated plots was reduced 89.3 percent from that 
in the nontreated plots. A report on Questel* s ( 542 ) experiments of 1938 
in the Lake States was published in 1940, giving the results stated a^ovo. 
Sprays and dusts of two fluorine compounds and phenothiazine spray also 
gave good control and v/ere about equal in their effectiveness. The fluo- 
rine compounds, howover, caused severe burning of the corn plants. Both 
standard nicotine tannate (0.0625 percent nicotine) and Quebracho nico- 
tine tannate (0.0625 percent nicotine) sprays v/ere low in inseotioidal 
performance in the Ohio tests. 
-^•SKS?-— 
