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A derris dust containing P. 5 percent of rotenone and 1.25 percent 
of ether extractives prevents the adult insects from laying their eggs 
in the blossoms. — De Bussy., et al (61_) in 19t36. 
The En.st Mailing Researqh Station, England ( 114 ), in 1936 reported 
that a proprietary derris po-^der ^as used in the routine spraying program 
in 1935 for the apple hloss-om T^eevil on apples. 
Two applications of a dust containing 0.75 percent of rotenone 
killed 50 to 80 percent. — Anonymous (2) in 1937. 
Kearns and Marsh ( 238 ) in 1937 reported that application of derris 
dusts at the early green-flower stage do not provide a sufficiently high 
control of the blossom T'eevil to warrant the expense. Sack banding 
applied to the boles of the trees in June at times prori-des a means of 
capturing large numbers of ^^eevils. It is desirable that the bands be 
removed from the trees before the end of October, and the p-eevils killed 
by immersing the sacking in derris wash. 
This' pest on apple trees vq.s mitigated by a product containing 12 
percent of powdered Lonchocarpus nicou root (of 6 percent rotenone content) 
and 88 percent of talcum, according to Stablissements Rotenia in a letter 
to R. C. Roark in 1938. . 
Hanf (174) in 1938 reported on the control of the apple blossom 
weevil. Of many insecticides tested, the pyrethrum-derris' preparations 
were the best. Quassia was useless. Nicotine often acted more quickly 
than pyrethrum and derris but the insects were only stunned and later 
revived. The opinion was expressed that an insecticide should be at 
least 90 percent efficient in laboratory tests to be potentially of 
commercial value, as in. ^practice not all insects are hit; hence the over- 
all efficiency is reduced. It was recommended (1) that trap bands. be 
applied to the trees in Jebruary (2) that the usual preblossom spray 
with supplements of pyrethrum or pyrethrum-derris be applied just after 
the first green on the buds, and (3) that in small orchards, bands be 
applied in June. 
Kearns and Martin ( 239 ) in 1939 wrote on the use of post-dormant 
combined sprays on fruit crops in England. Sprays containing 0.004 
percent of crystalline rotenone have been found satisfactory against 
fruit pests and are recommended for apple, plum, and Rubi crops. The 
addition of derris to the spray does not prevent severe infestations 
by the apple blossom weevil, although a high kill of weevils on the 
trees at the tine of spraying is obtained. The failure to prevent an 
appreciable infestation of the blossom is due' to the fact that it is 
only rarely that the greater part of the blossom weevil pop\ilation 
congregates on the tree at, any one time, and this may not coincide 
with the time of application of the spray, 
Niklas ( 305 ) in 1939 • reported that rotenone at 0.4 percent con- 
centration as a spray had killed. 100 percent of A. pomorum adults after 
spraying. 
