- 9 - 
In 1^37 approximately ^7.5 tens of dust iiixturep containing rotenr.r.ej 
cost 'ng apprcxiniately $10,925, were used to protect approximately 
38,000 acres of peas. In 1^3??, with an acreage of a;oproxi-aately 
3^,000 acres, a total of 211.5 tons of dust mixtures containing 
rotenone, costing approximately $37 > 7^0, were used. The general 
results of the control campaigns for the 2 years were nearly the sane, 
as in 1937 7l6 acres of peas, constituting 1.9 percent of the total 
acreage, were discarded on accov.nt of the pea-weevil damage, whereas 
in lP3g 386 acres, or 1.1 percent of the total acreage, were discarded 
on account of Dea weevil damage. 
The Idaho Agricultural Experiment Station (2l6 ) in 1939 reported 
that dusts containing 1 percent and 0.75 percent of rotenone gave good 
control of the pea weevil vrhen applied at the rate of 20 to ^0 poimds 
per acre. Experiments on garden plots indicated that control to the 
extend of 97.02 percent in peas of tatle size could "be accomplished 
with rotenone-'bearing dusts. 
An anonymous writer (_^) in 19^0 described the use of rotenone 
dust against the pea weevil in the ¥a,shington-Ore<^'on canning-pea 
section. Approved practice novr is to use a dust containing 1 percent 
of rotenone at the rate of 20 poijuids p- r acre betv^een the appearance 
of the first blooms ajid the first pods, usually 2 or 3 days. Cost for 
materials has "been around $1.50 per acre. Records of weevil dajnage 
were as follows: 
Acreage left uncut 
Acrea,se in iDeas "because of weevil damace 
1935 12,000 Not recorded 
1936 28,900 6 prrcrnt 
1937 38,000 .1.0 percent 
1938 3U,000 1.1 percent 
1939 32,000 0.7 percent 
Rotenono dust vras first tried in the field in 1*^35, and in 1937 
"big-scale dusting vrith power machines was used. "Various dust(^rs are 
pictured and descri"bed. 
Bruchus ruf imanus Boh,, th-- broad"bcan weo-^-il 
Liebster _(2^)in 19^0 reported that pyrothrum and derris dusts 
were effective against this siorcies. 
Callop'.obruchus chinenpis (L.) 
Trr-, hrosia Candida ac^ds and Derris olliptica roots, a"opli*"d as 
dusts tc Jr uchu s chirj_cnsig L. [Callosobruchus ohinrnsls (L.), according 
to- H. S. Barber, as stated by Muesebcck] , in stcr'^d puisos gave from 60- 
t-^ 100-pr-rcrnt mortality in 2k to 72 hours. — Bhatta and Narayanan (29) 
in 1938. 
