- 73 - 
Howard, Brannon, ?ini Mason ( 196 ) in 19?6 rrcoiinnendcd derria or cu"be 
sDray as the best control mpasxire for the Mexican tean bf^etle. Thrp>? pounds 
of powder (containing U percent of rotenone) p-^ r 100 gallons gi-'-'^s a roton- 
one content of about 0.015 perc^mt. The treatnent should be started when 
be; ties are found in the firld and should b' repeatrd at int^-rvals of 7 to 10 
days. Dusts contpining 0.5 percent of rotenone may be us^d at the rate of 20 
to 25 pounds per acre per ai-^plicatior.. Sprays are rccom-nended in preference 
to dusts for bean beetle control because spraying will giv<^ better control 
and longer protection to the plants. In the case of hoTie-mixed dusts, either 
talc, dusting 'sulfur, infusorial earth, kaolin (china clay) or oth/ r finely 
ground inert clay, gypsum, diatomaceous earth, vrheat flour, or tobacco dust 
may be used as a diluent or carrier, but recent experiments have indicated 
that talc is the most satisfactory. Dust<? containing 0.5 or 0,75 percnt of 
rotenrne should not be used for making sprays. Begin spraying when the adults 
are found in the field or when the eggs become n^ynerous on the undersides of 
the leaves. One to four applications ar*^ reonired, depending on the abundance 
of thf insect. 
Derris dust (0.5 to 0.75 percent of rotenone) applied at the rate of 
15 to 25 pounds per acre will control thr Mexican bean bf^etlc. — Kutson ( 212 ) 
in 1936, 
Langford and Crosthwait (256) in 193^ reported exneriments on the 
control of the Mexican be?Ji beetle. The experiments were made xmder conditions 
normally encountered in commercial bean production. The spraying wa.s done 
with a U-row traction siorayer with angl^ nozzles, and the dusting was done 
with a S'-row powp'r take-off, self-mirir.g bean duster. Tvo treatments were 
made with each material, on June 12 and June 26. The plants were chocked for 
bean beetle injury on July 3, The results for sprays were as follov/s: The 
plots treated with 2 pounds of magnesium arsenate in 50 gallons of water 
had 52.5 percent of the plants injured by the bcjtlc, whereas the plot treated 
with natural cryolite, 2 pounds in 50 gallons of wr.ter, had only I9 percent 
of the plants injured. Tvo pounds of a 2,5-p^rcent rotenone showed 25 percf^nt 
injury: bariu^i fluosilicatc, 1.25 pounds in 50 gallons of water, had 55 per- 
cent of the plants in,iur< d. The dustp of rotenone and pyrethn-i-m gave excell- 
ent ri-ralts. The plot drst-d with a 60-percent pyrethrom dn^t (0.05^ p<^rcent 
of pyrnth--ins), atrliod d', the rate of I6 pounds per acre, had 5,6 percent of 
the plants injured by th • b- roles. Anoth'--r plot dMszr^'. vrith a rotfnone du-^t 
(0.75 percent of rotenon>?) applied at the rate of -:o.5 pounds per acre showed 
only U.g perce'-.t of th^ plants injured by beetles, whereas anoth'-r plot dusted 
with a rotenone dust containing 0.5 percent of rocenone applied at the same 
r^tc had beetle injv.ry on 22.1 percent of the plants. 
The S-uth Carolina Agricultural Exreri^eit Station (^IfB) in I036 
rocor'imonded derris nr cub'"' s^or the control of the M, ::ican bean beetle. S-orays 
(3.5 pounds of powder containing 5 percent of rotenone per 100 gallons) ap- 
plied at thr rate of 100 to I50 gallons per acre gave slightly superior re- 
sults to dusts (0.5 or 0.75 percent of rotenone) applied at the rate of 20 
to 25 pounds pf r acre at each dusting. 
T;-e Unit-d State? Departrrent of Agriculture ( 38!) in 1^36 refrrred 
to the effective use of derris and cube against the Mexic-r^n bean beetle. 
