-75- 
earth balls were bumped out of pots and the roots bearing the aphids 
were dusted.— Bieberdorf and Fenton (61) • 
Fhorodon humuli (Schr.), the hop aphid 
In Bavaria it was recommended that nicotine be used until blos- 
som time of hops, and derris alone or with pyrethrum from then onward. 
— Hampp and Jehl (256) • 
In England some hop growers prefer to use a derris preparation 
instead of nicotine.— Mas see (4 023 . 
Rhopalosiphum pseudobrassicae (Davis), the turnip aphid 
Under field conditions a derris mixture containing 1 percent 
of rotenone with equal parts of finely ground tobacco dust and M 300- 
mesh" dusting sulfur as a diluent proved superior to a dust mixture 
containing 3 percent of nicotine. Good results were obtained with 
a spray containing 2 pounds of finely ground derris or cube root 
(4 to 6 percent of rotenone) per 50 gallons of water, at the rate of 
100 to 125 gallons per acre, at intervals of 7 to 14 days .--Allen 
and Harrison (ll); Harrison and Allen (267 ). 
Pyrethrum and 1-percent nicotine dusts were more rapid in their 
aotion than 0.2-percent rotenone-talc dusts, but derris and cube were 
as effective at the end of 30 hours as were pyrethrum and niootine. 
Timbo appeared less effective. Derris and Tephrosia were more ef- 
fective than Lonchocarpus of the same guaranteed. rotenone content* 
— Arant (22, 26;. 
It was recommended that dust mixtures containing nicotine be 
substituted for rotenone in combating the turnip aphid, although 
rotenone was preferred for this aphid on turnips. The revised recom- 
mendation for the war emergency was (l) the use of a 0.75-peroent 
rotenone dust, applied early and thoroughly at the rate of 35 to 40 
pounds per aore, and (2) whenever possible substitute a 3-percent 
niootine dust for the rotenone dust»— U. S. Bureau of Entomology 
and Plant Quarantine (626 ) • 
Rotenone was recommended for aphids on turnips in viotory 
gardens.— flfhite and Doolittle (683 ). 
Rhopalosiphum rufomaculata (Wils.) 
Acetone extracts of the roots of Tephrosia vlrginiana from 
Texas were highly toxic to this aphid. — Ginsburg and coworkers (227) • 
