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sulfate- sprayed plots and check- plots the ground was literally alive with 
aphitis., The rotenone remained effective against the aphids over a much 
longer period than did nicotine sulfate and soap. 
Graham and Ditman, of Maryland, (228) reported that in 1937 derris 
and cube sprays, when properly applied, gave good results. Fie o tine 
fumigation the most complete and quickest kill. Derris dusts, pos- 
sibly "because of improper application, seemed less effective than sprays. 
Derris powder (8-percent total extractives?) was used at the rate of .?. 
or 4 pounds per 100 gallons, plus sodium lauryl sulfate (3/4 or 1/2 
pound) or Orthex Spreader (1 pint) as a wetting agent. 
Ditman (Si) in December 1939 reported on the practical aspects of 
pea aphid control.; Busting with 0UD5 or derris (l percent rotenone) was 
probably the most commonly used treatment for the control of the pea 
aphid 'oy Maryland growers. Only a very small acreage was treated with 
the nicotine vaporizer and no nicotine dust was applied. The evidence 
from the observations on experimental and commercial treatments indicate 
that cube sprays were not so efficient as derris sprays for pea aphid 
control and that the additional cost of derris over cube will probably 
pay good dividends. Observations on commercial control indicate that 
derris is better than cube and that a' derris dust of 1 percent-rotenone 
content should be used by those who prefer dusting to spraying. All 
dusting should be done at night when the air is still and when vines 
are heavy with dew. 
Ditman, Cory, and Graham (?2) in August l c i39 reported tests on 
the control of the pea aphid in Maryland in 1938- The following were 
tested as sprays: Derris + Areske't (rotenone 2.6 percent); cube: cube 
plus Vat sol CS (rotenone 3«2> percent); Agicide (1937 pack, stated to con- 
tain 1 -percent rotenone). The derris and cube were used at the rate of 
4 pounds per 100 gallons. Agicide and derris gave a greater reduction 
of aphids 'oer sweep and per tip than did cioe. Agicide gave a slightly 
higher kill of aphids than either derris or cube and derris gave- a. better 
kill than cube, by all three of the, methods of population estimation. 
Further examination- of the results shows that the treatments held the 
aphid population in check for a period cf approximately 10 days, though 
the percentage of infested, tips increased slightly in plots treated with 
Agicide and cube, derris remaining about the same. This increase in the 
number of tips infested after spraying tends to discount the idea of any 
residual effect of the spray. ' 
In the severe and extended infestation of the pea aphid of 193^, 
one application of insecticide was*. not sufficient -to obtain -good control.. 
There was little difference in yield of nlots receiving a single early 
' q rp 
application of cube and those receiving a si nglby application, as neither 
treatment .gave satisfactory control. The number of aphid? per sweep, 
aphids per tip, and the percentage of tips infested were satisfactory 
indices to the degree of control obtained by various spray treatments. 
Sometimes, however f counts of all p,phids on entire plants showed that 
the above estimates of populations indicted a greater percentage reduc- 
tion than actually occurred. 
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