
Figure 1,--Seedling survival in greenhouse of Cody (labeled 22 clones) compared with Buffalo alfalfa after infesta- 
tion with spotted alfalfa aphids, (Harvey et al., 1960.) 
Table 1.--Original records at time of release of Cody. (Modified from 
table 1, Harvey et al., 1960.) 


Alfalfa variety 
Resistant cody 
CioneS wor seedlings, swam nee 
Lahontan clones or seedlings... 
Susceptible Buffalo clones 
or seedlings... 
OOD COON CeO OUD 
For a number of years, Oklahoma and, to a 
less extent, Kansas have carried on research 
toward production of small grains resistant to 
the greenbug, Schizaphis graminum (Rondani). 
That aphid comes into Kansas from the south, 
and often severely damaged barely, wheat, and 
oats in late fall and early spring. A single 
genetic factor for resistance is known in wheat 
and two in barley. Wheat and barley hybrids 
that carry the genes for resistance have been 
142 

Nymphs per female Mean 









in 7-8 days seedling 
survival 
Percent 
studied in yield tests in both States. Resistance 
to greenbugs (fig. 2) can be just as striking 
as resistance to the spotted aphid in alfalfa in 
either the green house or the field. The compo- 
nents of resistance involved are differentfrom 
those in alfalfa to spotted alfalfa aphid. In both 
wheat and barley the principal characteristic 
of the resistant plants has been their ability 
to withstand infestation (tolerance). In wheat, 
fewer young are usually produced on resistant 

