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Pentalonia nigronervosa Coq. 
Ocfemia ( 215 ) in 1931 wrote on bunchy-top of abaca in the Philip- 
pines and its control. This disease is caused by a virus which is spread 
from plant to plant by the aphid P, nigroner vosa . For control the stools 
should be dug up, chopped in pieces,' and sprayed with nicotine or derris 
spray. The soil around the stools should also be sprayed. Derris spray 
is prepared from 1 kg. of derris roots and 10 liters of water: "Pound 
the roots of derris thoroughly and macerate them in water over night. 
Strain through cloth. For use take 1 part of the infusion and dilute 
it with 10 parts of water." 
Per iphyllus lyro pictus (Kess.), the Norway-maple aphid 
Hamilton and Cemmell (137) in 1934 reported that in nursery tests 
against the Norway-maple aphid derris dust (l percent rotenone) killed 
40 percent. 
Pho ro do n humuli (Schr.), the hop aphid 
Winston ( 312 ) in 1926 reviewed information on Derrisol for the 
benefit of Florida citrus growers* Reference was made to its use against 
hop aphids in England. Derrisol should be diluted 1:800 for use against 
aphids. 
Derris or rotenone suspensions at concentrations of 1:5,000 or 
1:6,250 were effective.— DeBussy et al. ( 52 ) in 1935. 
Hampp and Jehl (139) in 1938 reported that sprays of derris alone 
and with pyrethrum gave excellent results against hep aphids on hops in 
Germany, It was recommended that nicotine be used until blossom time, 
and derris or derris with pyre th run from then on. 
Warwick ( 3C0 ) in 1938 reported that in England derris products 
are used very effectively against the hop aphid. 
Pterochlo rus tropical is Van der Goot 
Neoton (derris extract in fish oil) 225 gm. plus an equal weight 
of soap, in 40 imperial gallons of water, killed 100 percent. --Institute 
of Physical and Chemical Research (162) in 1927. 
Phopal o s iphum prunifoliae (Fitch), the apple grain aphid 
Headlee ( 145 ) in 1026 reported that Derrisine diluted 1:100 in two 
tests permitted 52 and 32 percent of the eggs of ( Aphis avenae F. ) 
Rhopal os iphum prunifoliae to hatch as compared with an average of 58.8 
percent in the checks, 
A block of 10 young Delicious apple trees was sprayed with a 
mixture consisting of 3 pounds of colloidal copper fungicide, 1 pound of 
derris (5 percent rotenone), commercial oil emulsion to give 3 percent 
actual oil, and 100 gallons of water. The sprays were applied during the 
