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BN—29526 
In this test at Reno, Ney., the stem nematode Ditylenchus dipsaci damaged the susceptible alfalfa variety Ranger. 
Lahonton had been bred for resistance. 
To develop resistant varieties we need new or addi- 
tional research on— 
®@ Nature and extent of losses from specific diseases, 
insects, and nematodes. 
Pathogenicity and life cycle of disease organisms. 
Identification of races within pathogens. 
Techniques for culturing pathogenic organisms. 
Transmission of diseases and effective artificial 
inoculation procedures. 
@ Development of rapid and reliable techniques for 
isolating resistant stocks, or for devising other 
disease-control measures. 
® Response of plants to various combinations of dis- 
seases, insects, and nematodes. 
® Mechanism of resistance to diseases, insects, and 
nematodes. 
@ Inheritance of resistance. 
Development of lines with multiple resistance to 
diseases, insects, and nematodes. 
Research on Tolerance or Resistance 
to Environmental Hazards 
Environmental hazards cause seeding failure and 
slow growth of grasses and legumes, and loss of mature 
plantings. Environmental hazards also increase losses 
Factors influencing plant survival are studied in the 
laboratory, the greenhouse, and the field. In this field 
experiment at Clemson, S.C., the lifespan of individually 
marked white clover stolons is recorded. 
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