240 THE PEANUT— THE UNPREDICTABLE LEGUME 



nut plants on soil treated with DDT at rates of 25, 50 and 100 pounds 

 per acre, yielded 48 percent more peanuts than those on untreated soil. 

 Thus it appears that control of white-fringed beetle on peanuts by treat- 

 ment of the soil with DDT is feasible. Dusting the foliage of peanuts to 

 kill the adults is also feasible but, where soil treatments are employed, 

 may not be necessary. Incidental control may be had by dusting for con- 

 trol of potato leafhopper. 



Information available on the control of white-fringed beetle has been 

 summarized (68). DDT is the most effective insecticidal treatment 

 known for control of the pest. It may be applied to the soil for control of 

 larvae or to the foliage of plants for control of adults. Ten pounds of 

 technical DDT per acre has remained effective in the soil during a 5-year 

 period, and the tests are still in progress to determine the length of 

 effectiveness. 



The insecticide may be applied as dusts or sprays. For spraying, 50' 

 percent wettable powder in concentrations of 2.5 to 5 percent has been 

 most effective. 



In treatment of foliage to kill adults of the white-fringed beetle, DDT 

 should be applied at the rate of J^ to 1 pound of technical per acre at 

 2- to 3-week intervals during the season of beetle emergence. The insec- 

 ticide may be applied in the form of dusts or sprays. Sprays are usually 

 prepared from wettable powder or emulsifiable concentrates. 



Since the major part of the research on white-fringed beetle is being 

 conducted by the U. S. Bureau of Entomology and Plant Quarantine, this 

 agency should be consulted for latest recommendations on control. 



Only limited information is available on the effect of rotation and 

 other cropping practices on control of the white-fringed beetle. Additional 

 research is needed on these points. Additional information is also needed 

 on the long-time effect of soil treatments with DDT on productivity, soil 

 organisms, fish and wildlife, and water supplies. 



Soil Insects 



Several species of soil insects attack peanuts and cause an undeter- 

 mined amount of damage. In addition to the white-fringed beetle, which is 

 discussed in another section, damage to underground parts is caused by 

 several species, including soutliern corn rootworm, larvae of the banded 

 cucumber beetle, two species of wireworms, white grubs, and the lesser 

 cornstalk borer. 



One of the first references of damage to peanuts by soil insects was 

 made by Fink (56), who found southern corn rootworm, Diabrotica du- 



