10 ANNUAL REPORTS OF DEPARTMENT 01" AGRICULTURE, 104 1 
In 1 1 10 exploratory tests of inbred lines and open-pollinated varieties, 
f> out of about .'if»0 sweet -corn entries were promi>ing as borer- 
reeistant breeding material, and n<> additional resistant field lines were 
found among approximately 900 field-corn entries tested. It was de- 
cided t hat in del prminrng t he ability of a variety to resist borer attaek 
the following factors should be considered: Type and rate of plant 
growth, pollen accumulations that serve temporarily a- food for the 
larvae on different parts of the plants, and comparative abundance 
of the sucking bug Or'ms 'rnx'/rfiosHs Say. that prey- on the eggs and 
Larvae of the corn borer. 
In testing over 4,000 varieties of sugarcane for re-Utance to the 
sugarcane borer. 2 were found promising for use as resistant parental 
material in breeding work. Forty— ix classed as resistant in previous 
tests maintained this status in the 1943 trials. In the investigation of 
commercial varieties it was found that susceptible varieties produced 
245 pounds less sugar per acre when heavily infested than when lightly 
infested, but that none of the resistant varieties produced less sugar 
per acre when heavily infested. 
DEVELOPMENTS IN CORN EARWORM CONTROL 
Tests of mineral-oil emulsions, with and without pyrethrins. atom- 
ized on the ear silks showed that there is a possibility of controlling 
the earworm by this method at less cost than when the oil-injection 
method is used. This might make their application to canning corn 
practicable. In preliminary tests an infusion of a bacterial disease of 
the earworm sprayed on the silks or injected into them did not inter- 
fere with pollination but did result in a fair degree of control. This 
method of control may have possibilities if a cheap method of culturing 
the bacterium in quantity can be devised. 
WINTER GRAZING CONTROLS PEA APHID ON ALFALFA 
Grazing of alfalfa in the Antelope Valley of California until March 
1 prevented the. development of severe early-spring pea aphid infesta- 
tions except in some fields that were reinfested by migrants from tin- 
grazed fields. In previous years late-winter or early-spring grazing 
of alfalfa in western Nevada satisfactorily disposed of spring aphid 
infestations. 
GRASSHOPPER POPULATIONS AT A LOW EBB 
Owing to the generally cold, wet springs of 1943 and 1944 and un- 
favorable conditions for fall egg laying in some areas, grasshopper in- 
festations in the Great Plains and Rocky Mountain States have been 
Considerably reduced and more local in character. Conditions were 
more favorable in Arizona and California, however, with attendant 
high poptdat ions in some localit ies. 
LATE-SEASON BATTING OF ADULT GRASSHOPPERS A PROMISING LOCAL 
PREVENTIVE MEASURE 
Large-scale poisoning of adult grasshoppers when they are congre- 
gated on their favorite egg laying grounds late in the season was tried 
during 1943 in several California and Montana localities. The results 
indicate that this may prove to be an economical measure for prevent- 
