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was little difference in any of the test olots. Cn another ranch one 
application of 25 pounds per acre of a derris-dust mixture gave 99- 
percent control of hoppers, 
Hamilton and Gemmell ( 157 ) in 1934 compared the effectiveness of 
derris, pyre thrum, and hellebore pov.'ders against different insects. 
Dusts containing derris root po-.'der (air-floated, 4 percent rotenone), 
pyrethrum powder (1.16 percent pyrethrins), mixtures of these tiro, and 
hellebore ponder (0,8 percent active principle) were tested. Inert 
clay t.us used as a diluent. In field tests against the grape leaf- 
hopper, derris ponder, pyre thrum powder, and mixtures of the two gave 
satisfactory control uhen dusted either by hand or by machine. Appli- 
cations v.ith the power duster, at the rate of 100 pounds per acre, showed 
that dusts containing derris ponder equivalent to 0,5 percent of rotenone 
were nearly as effective as these containing 1,0 percent of rotenone. 
Hellebore was ineffective against the grape leafhopper. Heavy applica- 
tions of a dust containing 1,5 percent of nicotine knocked dov.n the 
grape leafhoppers but did not kill them, and all stages recovered in 1 
to 2 hours , 
The Idaho Agricultural Experiment Station ( 160 ) in 1936 reported 
that cube-kaolin dust (0,2 percent rotenone) was effective against this 
insect. One thorough dusting of Virginia Creeper killed most of the 
nymphs and adults of the grape leafhopper and a second dusting 10 days 
later produced complete control. Two dustings 10 days apart controlled 
this insect on grapes. 
Foliafume (a pyrethrum-derris spray v.ith spreader) at 1:400 
killed 95 percent in 48 hours. — Penick and Company ( 223 ) in 1936, 
Stearns, Haden, and T.illiams ( 252 ) in 1S36 reported that. Cubor 
(a rotenone and pyre thrum liquid spray) at 1:400 or 1:800 gave "adequate 
control of Erythro neura sp, in vineyards in Delaware, 
The Idaho Agricultural Experiment Station ( 161 ) in 1937 reported 
that a kill of 94,31 percent of the grape leafhopper was obtained v.ith 
one spray containing 0.49 percent of nicotine sulfate and 0,63 percent 
of summer oil. Better and more lasting results were obtained with this 
combination than vith derris or cube ponder in either dust or liquid 
fori or vith pyrethrum spray, Derris as a spray was more effective than 
as a dust. 
Parks and Pierstcrff (219) in 1938 recommended a 0,75 percent 
rotenone dust for the control of leafhoppers on grapes, 
Euptc ryx flavo scuta van, nigra Osb. 
KcBride ( 1S5 ) in 1926 reported tests vith insecticides against a 
leafhopper, Eupt-nryx flavo scut a var, nigra Csb,, attacking the leather 
fern ( P olys tichum capense J, Sm. ) in Florida, Five percent extract of 
derris, 1:800 plus soap, 2 pounds to 50 gallons, gave satisfactory con- 
trol. At the end of 5 hours 93,2 percent were dead and the following 
day 95 percent were dead. Spraying v.ith nicotine sulfato 1:800 plus 
seep, 2 pounds to 50 gallons, pins 5 percent extract of derris 1:800 
