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When derris contains a higher rotcnone content, loss of the material 
may "br usr-d to ottain sprays of the rotenone content mentioned above. No 
sprerder or sticlcer i<? renuir^d. 
DUSTS 
Finished dust to contain 0.5 to 0.75 percent of rotenone. 
Derris (U percent rotcnone content) 12.5 pounds, talc or other diluent 
87.5 pounds. 
Derris (U percent rotenone contr-nt) I9 pounds, talc or othrr diluent 21 
pounds. 
Other diluents that may be used are infusorial earth, kaolin (china 
clay), dusting gynsum, wheat flour, or tobacco dust. Fine dusting sulfur 
may be mixed with the infusorial earth or clay to the extent of 25 pounds 
of the sulfur substituted for a like amount of the earth or clay. Home- 
prepared dusts may be thoroughly mixed by placing the ingredients in a drum 
or barrel, not over two-thirds full, and rolling and tilting it for 5 niinutes. 
Com'^ercial dusts may be obtained already mixed. Dusts are usuai'.ly applied 
at dosages of 20 to 25 pounds to the acre on bunch bepiiQ, but when careful 
applications are made the dosage mav sometimes be reduced. 
Walker and Anderson ( U07 ) in 1935 wrot^ that bean growers reported 
obtaining very satisfpctory control of the Mexican bean beetle with a derrig 
dust containing 0.75 percent of rotenone applied at thf rate of I5 to 20 
pounds per acre and some growers reported getting good control with 10 pounds, 
per acre. 
White (M^) in I935 recom^nended derris sprays (0.02 or 0.025 P' rcent 
of rot-none) and dusts (0,5 to 0.75 percent of rotenone) for the control of 
the Mexican bean beetle. 
Brannon (j^) in 193^ reported that best simultaneous control of the 
Mexicr.n bean beetle and powdery mildew on snap beans at Norfolk, Va., was 
obtained by adding 2 pounds of wettable sulfur to derris- or cube-pcwdor 
suspensions containing about 0.02 percent of rot^mone or by diluting derris 
or cubr- pov/der with sulfur to a rotenone cont' nt of 0.5 percent. 
Brannon (^) in I936 summarized the result" of the field control 
experiments of 1935 ageinet the Mexican bean beetle on lima beans at 
Mappsville, Va. , as follows! In an exprrimrnt conducted on l/2-acre plots 
of Forc'liook lima beans (using powf^r machinery) in which cryolit--^ sprp.,y (3*50), 
powdered derris-root spray (O.O25 percent of rotenone), cryolite-talc dust 
(60:Uo), and derris-talc dust (0.22 percent of rotenone) were compared. The 
results after six treat-nents showed that cryolite spray (3:50) was equally 
as effpcti-'-e as powdered derris-root spr?y (0.025 percent of rotcnone), and 
that cryolite-talc dust (GOsUo) gave a considerably larger yield increase 
than did dcrris-talc dust having a rotenone content of 0,22 percent. In 
comparing tht yield increases at the time of the vprious pickings of this 
long-grovfing crop, there was an indication that powdered derris-root spray 
felled to afford the re<!idual effect obtained following a-pplications of the 
cryolite spray. This had not been observed on the relatively short-growing 
snap-bean crop. The net profit p'^r acre due to tre>atment was considerably 
greater from the application of cryolite spray than from the oth«r materials 
used in the experiment, partly because of the higher yield increase obtained 
with cryolit'- but mainly because of the lower cost of that treatment. 
