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than 3.6 percent of rotenone, when used at the rate of 1 pound per 100 gallons 
with 3 quarts of kerosene, is effective in reducing infestations of the Pacific 
mite. 
Moore et al. (107) in 1941 reported on control of the Pacific mite and the 
European red mite on apples. Although mites have been a serious pe-st on apples 
in Washington for many years, no satisfactory method of control hajs/hertof ore 
! been found. Infestations present early in the spring are generally kept down by 
the regular codling moth spray program; the sprays, applied under high pressure, 
wash some of the mites off the trees. In July, when the oodling-moth spray 
program tapers off, the mite infestations build up. At this time it is dangerous 
to use more than 0,75 percent of oil on the trees and this is not sufficient 
to kill both mites and eggs, for which about 1.5 percent of oil is necessary. 
The use of derris, with 0.5 to 0.75 percent of oil, increases the kill of mites 
somewhat, but does not kill the eggs; hence the infestation soon builds up again. 
Because of climatic conditions and the use of oil in codling moth sprays it is 
dangerous to use sulfur compounds for mite control in Washington. 
Tctranychus telarius L. 
The Experimental and Research Station of the Nursery and Market Garden 
Industries' Development Society Ltd., of Cheshunt, Herts, England (_57) in 1934 
reported tests -with spray fluids, purporting to contain rotenone, for the con- 
trol of the red spider mite on potted plants of Arum and tomato. A dosage of 
1/2 fluid ounce of concentrate to 1 gallon of water was applied. On the Arum 
foliage about 1 percent of the adults remained alive 2h hours after spraying. 
On the tomatoes several adults and deutonymph resting stages were alive 12 days 
after spraying. Infested plants in a greenhouse were thoroughly sprayed with 7 
fluid ounces of concentrate to 12 gallons of water. Ten days later a consider- 
able number of mites were alive on the sprayed foliage. Tomato shoots infested 
with mites were sprayed with an emulsion consisting of 0,12 percent of rotenone, 
5 percent of acetone, and 1 percent of saponin. After 2h hours all the mites 
appeared to be dead except one larva, which probably hatched after spraying had 
been finished. After Us hours the following mites were collected: Dead, 5 
females, many young stages; moribund, 3 females; alive, 1 female and 12 larvae. 
Five days after spraying many mites were alive and had migrated to the upper 
surface of the foliage. The conclusion reached was as follows: 
"A reasonably good control on commercial nurseries is certainly 
not to be expected from sprays containing this substance [rotenonej . " 
The same station ( 5%) , in 193° reported that many commercial derris sprays 
and dusts had been tried for the control of the. red spider mite on young tomato 
plants. Dusts containing derris were without appreciable action on the mite, 
but several s;orays containing emulsified derris extracts, or finely ground derris, 
together with a wetting agent, showed considerable toxicity to the mite in small 
-scale trials conducted early in the season. Control of the pest was obtained 
in February by two applications of these sprays to badly infested cucumber and 
tomato plants. Extended trials throughout the season, nowever, showed that a 
