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The dust should be applied at the rate of 20 to 25 pounds per acre, based 
on 3-1/2- to 4-foot rows with two rows of plants to each field row. Ordi- 
narily treatments should be made at 7- to 10-day intervals for best results,! 
Under field conditions sprays have not been so satisfactory as dusts 
against the turnip aphid or: turnip and mustard. It is difficult to roach 
the lice on the undersides of the leaves, especially on large plants. If 
a spray is preferred, a nicotine sulfate-soap solution is recommended* 
The United States Department of Agriculture, Bureau of Entomology 
and Plant Quarantine ( 273 ) in its annual report for 1935 stated that 
experiments on the turnip aphid in Louisiana indicate that derris dust 
may satisfactorily proteotjthe turnip crop from damage. In its annual 
report for 1936 the Bureau/stated that in tests directed against the turnip 
aphid in Louisiana insecticides containing rotenone, with sulfur and talc 
as diluents, were in general more effective in producing a satisfactory 
market product that wore insecticides containing nicotine. In 1939 the Bur 
(285) reported that insecticides containing rotenone had proved effective. 
Fenton ( 101 ) in 1936 referred to the report of Allen (£) and to 
unpublished work by Roney of Texas, who reported very good results at 
Dickinson with a dust containing 10 pounds of powdered derris or cube (5 
percent rotenone), 15 pounds of pyrethrun dust (0,5 percent pyrethrins), 
and 75 pounds of 300-mosh conditioned sulfur. The dust did not cause 
any burn of the turnips and when applied early in the morning or late in 
the afternoon, v/hen dew was present and very little wind, it controlled 
this inspect. It was effective at temperatures as low as 45° F, 
Harrison ( 141 ) in September 1936 reported the results of field tests 
with in secticides" against the turnip aphid on Purple-top Globe turnips and 
Florida broadleaf mustard, at the Baton Rouge, La,, laboratory, of the 
Bureau, of Entomology and Plant Quarantine. A dust mixture containing 
1 percent of rotenone, with equal parts of tobacco dust and sulfur as 
diluents, was superior to derris sprays, and dust mixtures containing 
nicotine sulfate. The dust mixture containing rotenone not only gave 
satisfactory reduction in the aphid population immediately after treat- 
ment but continued to inhibit the increase of aphids for a period of at 
least 6 days. Derris sprays ranked second in effectiveness against the 
aphids. A nicotine sulfate-dust mixture containing 3 percent of nicotine 
was effective against the aphids for a short period after application but 
did not afford adequate protection for so long a period as did the derris 
dusts or sprays. 
The Texas Agricultural Experiment Station ( 265) in 19 36 reported 
that for the control of R, ps eud ob ra s s i ca e a sulfur dust containing 0,075 
percent of pyrethrins and also 0,5 percent of rotenone gave results 
inferior to Nicotrol (a nicotine product) at a dilution of 1:300, applied 
by means of a fan-shaped nozzle, 
Deshpande (77) in 1937 reported that usually two species of aphids, 
Myzus per si cae andT*S ipho c oryne indobrassicae Das) Rho palosiphum pseudo - 
brassicae , are found attacking cabbage, in India and that both of them go 
under the common name of cabbage aphid. In 1932 Derrisol at 1:800 killed 
100 percent of the aphids. Derrisol is net now manufactured, hence is 
no longer available. 
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