- 19 - 
Hervey (157, 277 ) in 1935 reported that cabbage aphids vrere not satis- . 
factorily controlled by derris or cxibe du^t mixtures. 
The Tev York State Agricultural Experiment Station ( 212 , 213 ) in 
1935 reported that derris dust (0.5 - percent rotenone) had little. value in 
protecting Danish cabbage against the cabbage aphid. In 193& this station 
reported that aphids in the cauliflower seedbed were effectively controlled 
with dusts containing 0.5 and 0.33 percent of rotenone, the applications 
being made late in the evening under calm conditions, in anticipation of ■ 
a period of high relative humidity during the night. 
Veitch ( 290 ) in 1935 reported that derris sprays are highly effec- 
tive for the control of the cabbage aphid. 
Walker and Anderson ( 296 ) in 1935 reported the following results 
when cabbage plants were dipped in concentrations of derris preparations 
strong enough to control cabbage aphids: 
Percentage sur\'ival of plants 
Material Concentration Tops Tops and roots 
dinued dipped 
Pysol 1:100 96 7^ 
Red Arrow - - -" - 1:100 96 95 
Super Agricultural Spray 1:100 93 gl 
Derris dust failed to give satisfactory control. — Walker and 
Anderson (297) in 1935; also reported "oy Cory (277) in 1935- 
In laboratory tests a dust containing 50 parts of derris (3*95 
percent rotenone) and 50 "^arts of gypsum caused 20-"oercent mortality in 
2 days. In field experiments dusts containing 25 percent of derris proved 
unsatisfactory. — Kelsall and Stultz (170) in 1537. 
College 
Dibble, of Michigan State/, in advertising literature in 193^, recom- 
mended derris or pyrethrum dust or spray for the control of cabbage aphids. 
Earl-- control keeps the population low a.v.6. prevents much difficulty later. 
Sprays do not stick well on cabbage, and dusts are often given first 
choice. In large patches spraying is cheaper if good equipment is available, 
Gunderson ( ijM ) of Iowa State College Extension Service in I93S 
recommended derris or cube dust for the control of cabbage aphids. Pether- 
bridge and Wright (226) in I93S reported derris dusts to be inferior to a 
3 percent nicotine dust for the control of the cabbage aphid. Howard and 
Nelson (155) in 1939 reported that a nicotine-hydrated-lime dust mixture 
(2.U percent nicotine) was much more toxic to this insect in southern 
Ohio than were dust mixtures containing 1 percent of rotenone derived from 
cube and containing either sodium oleyl sulfate or peanut oil as condition- 
ers and either talc or a mixture of equal parts of tobacco dust and sulfur 
as diluents. None of ,the dust mixtures containing cube gave satisfactory 
control of this aohid. 
