Red cloyer plant (left) shows “internal breakdown”’ disease (dark area in root); right, healthy plant. 
apparently caused by agents other than micro-organisms, is responsible for substantial stand losses. 
breakdown,” 
Research To Develop Disease, Insect, 
and Nematode Resistance 
Diseases, insects, and nematodes reduce stand den- 
sity, persistence, yield, and quality of grasses and 
legumes grown for forage, turf, and seed. Diseases 
alone reduce the total value of these crops by an esti- 
mated 11] percent each year. Use of many grasses and 
legumes is restricted by lack of varieties that are resist- 
ant to diseases and insects. 
We have made progress. Development of alfalfa 
varieties resistant to bacterial wilt and spotted aphid 
has removed two serious threats to the alfalfa industry. 
Use of varieties resistant to bacterial wilt has increased 
returns to farmers by an estimated $100 million a year. 
Efforts are continuing to develop varieties resistant to 
the alfalfa weevil and to isolate lines with resistance 
to other major pests. 
BN—29533 
“Internal 
Insect damage is severe on 
Cooperation with entomologists 
(Photo 
courtesy of Mississippi Agricultural Experiment Station.) 
Weevil on crimson clover. 
many forage crops. 
has helped to identify sources of resistance. 
9 
