
Figure 2,--Relative damage by greenbugs to seedlings of Reno and Dicktoo (standing) barley grown in greenhouse, 
Similar differences occur in field. 
plants, but often the differences are not 
statistically significant. In barley, aphids on 
resistant plants usually produce about half as 
many young as on susceptible plants (table 2). 
The barley variety Will, a selection from a 
cross Kearney (resistant) Rogers (suscep- 
tible), produced at the Oklahoma Agricultural 
Experiment Station in cooperation with the U.S, 
Department of Agriculture, has been released 
to farmers in Oklahoma and in 1964 approved 
for release tofarmers in Kansas, We anticipate 
that when the variety Will is planted on large 
acreages, a 50 percent reduction in greenbugs 
each generation as they move across Oklahoma 
and Kansas in the spring should furnish con- 
siderable protection to susceptible wheat, 
barley, and oats and reduce the aphid popula- 
tion migrating north. Thus, it is important to 
emphasize that equivalent or similar resist- 
ance in the field or greenhouse can result 
from different components for resistance and 
different amounts of each in a variety. Cody 
alfalfa and Will barley are excellent examples 
143 
Table 2.--Greenbug resistance in Will barley 
compared with resistant and susceptible 
variety in Oklahoma tests 











; Greenbugs Average | Bushels 
ake per foot | Plants per 
per foot acre 






Number Number 
Infested: 
Omul gain. tere 31 17 70.6 
Weel ee cretek 24 16 68.6 
Rogers 53 3 9.8 
Not infested: 
Omugi- <5. 0 iby 65.2 
Wiis renevets 0 17 69.2 
Rogers. ..- 0 a UBS 
ee a ee, [een eee | ee ee 
