- 7 - 
The Ne^ York State Agricultural EjqDoriment Station (303) in 
1939 reported that rotenone dusts showed promise in controlling the 
pea wopvil in the field. 
The Pea Weevil Conf-erence ( 315 ). held in Spnkano, Wash., in 
1938, recr«mmended rotenone dust for the control of the pea weevil in 
caxining and garden peas. Talc is a good diluent; the roten^^ne content 
should not "be less than 0.75 percent; and 20 to 25 pounds should iDe 
applied per acre "by an efficient dusting machirts. fne to three applica- 
tions starting within a few days of 'blociDing are necessary. 
The- United States Department of Agriculture, Bureau of Ento- 
mology and Plant (Quarantine ( 396 ) in 1938 recommended dusts contain- 
ing not less than 0,75 percent of rotenone for the control ef the 
pea weevil infesting garden peas and also peas gro^Ti for canning, 
for the grepn-pea market, and for seed. Either derris or cuoe may 
"be used as the source of rot^-none; and talc or some similar inert 
carrier may "be used as a diluent.' Applications of from 20 te 25 
pounds of thp dust mixture p^r acre, if applied with an efficient 
dusting machine, should givf» satisfactory results. In heavy inf'-'S-f 
tations, as in some "border-strip plantings, the use of an additional 
5 pounds of the dust mixture por acre should give greater assurance 
of ^rntrol. The first application should "be made within a fev days 
after the peas start to bloom and "before f^r^ pcds have formed; ether- 
wise the weevils may lay eggs on the young pcds. Additional \^eevil 
populations may fly intf> some (^f the fields; in these cases cnp cr 
two additional applications may "be necessary. The date of these later 
ag^plications depends '^n the time the wpevil population increases in the 
field. In m«st instances a 6- to lO-day interval "between applications 
has "been satisfactory. 
The United States Department of Agriculture, Bureau of Ento- 
mology and Plant Quarantine ( 398 ) in 1938 reportpd that "bielrgical 
end. control investigations on the pea wepvil as a pest of processed 
and dry peas were continued in the Northwest in cooperation with the 
States •f Washington, 0reg(^, and Idaho and interestpd growers, ^ith 
gratifying results. The large-scale field ejsppriments in the Blue 
Mountain area of eastprn Washington and Oregon, in which dust mixtures 
containing rotpnone were applied, yielded favora"blp results, as in 
1937, C«mparativp treatments showpd that the use of hoods on large 
dusting machines increased the efficienc:" of these dust mixturps. No 
approcia'ble differpnces could "be detected in thp pprcentage of pea 
weevil control obtained with dust mixtures containing 1 percent, as 
compared with those containing 0,75 percent of rotenone, when the 
quantities of the dust mixture applipd p^r unit area were practically 
enuivalent. The rpsults, howpver, indicated that under unfavorable 
climatic conditions or othpr restricting factors the dust tnixtures 
containing less than 0,75 pprcent of rotenone might not give a satis- 
factory degree of control. In largp acrea^^es, the practice of treat- 
ing bordpr strips was followed to -nrotect the rest of the field. In 
some instancps "spot dusting" was practicod to rpducp infpstation. 
