WASTES IX RELATION TO AGRICULTURE AND FORESTRY 



81 



atomic radiation, by use of chemicals that sterilize 

 insects, or by achieving genetic sterility by cross- 

 ing genetically incompatible lines. 



Bioenvironmental methods of controlling in- 

 sects continue to offer promising lines of research. 

 The approach has a long history since such meth- 

 ods were among the few ways of controlling in- 

 sects before the development of most modern in- 

 secticides. 



Cultural control methods that are desirable 

 agronomic practices are often readily adopted. 

 When such measures are based on a modification 

 of necessary farm operations, they are cheap 

 methods of control. Fall plowing results in high 

 mortality of overwintering forms of the corn ear- 

 worm and the European corn borer, and thereby 

 reduces the number of adult- that emerge the fol- 

 lowing spring. 



Infestation of the grapeberry moth has been 

 greatly reduced by burying the overwintering 

 cocoons under a layer of soil so that the moths are 

 unable to emerge and make their way to the sur- 

 face in the spring. 



A mechanical method of controlling cotton boll 

 weevils is being developed. It involves picking up 

 and destroying cotton squares that have been 

 punctured by weevils, killing the larva, and break- 

 ing the life cycle. 



Burning trash in sugarcane fields has destroyed 

 as many as three-fourths of the overwintering sug- 

 arcane borers. 



Destruction of tobacco stalks after harvest re- 

 duces the number of late-stage tobacco worms, to- 

 bacco budworms, and corn earworms. 



Production of mosquitoes, horseflies, deerflies, 

 and other pests that breed in aquatic and semi- 

 aquatic habitats can be minimized and in some 

 cases prevented by proper alterations of the en- 

 vironment and by appropriate water management 

 procedures. 



Logging western pine on a selective basis — 

 "sanitation salvage" — prevents the tree-killing 

 western pine beetle from getting a foothold in the 

 stand. This approach was the basis for studies in 

 California showing that the trees most susceptible 

 to attack could be identified by visible 

 characteristics. 



The insecticide era brought about curtailment in 

 the study and practical use of many cultural prac- 

 tices for insect control. Yet, with insects becoming 



resistant to many insecticides and the emergence 

 of many problems resulting from insecticide resi- 

 dues, there is a resurgence of interest in research 

 towards improving cultural control. In some cases, 

 cultural and bioenvironmental methods may elim- 

 inate the need for using insecticides or may re- 

 duce the number of applications required. This 

 would contribute to the avoidance or amelioration 

 of contamination in the environment, 



Electromechanical devices for capturing and de- 

 stroying insects are receiving more and more re- 

 search attention. The attractiveness of various 

 wavelengths of radiation for stimulating responses 

 in insects has been known for many years. Until 

 recently, practical usefulness of the approach has 

 been quite limited. Extensive early work on light 

 traps for such insects as the European cornborer. 

 tobacco hornworm, and codling moth failed to pro- 

 vide practical results. In 1952, cooperative re- 

 search between the U.S. Department of Agricul- 

 ture and the Texas agricultural experiment station 

 revealed that the pink bollworm moth was readily 

 attracted by radiation in the near ultraviolet 

 region (black light). 



The Indiana agricultural experiment station 

 found that insect traps equipped with black-light 

 lamps were effective in reducing losses due to 

 cucumber beetles. 



Recent results of a 3-year experiment showed 

 that using three black-light traps per acre in a 

 large-scale experiment, integrated with other con- 

 trol procedures, reduced tobacco hornworm popu- 

 lations and greatly curtailed the need for 

 insecticides. 



The more favorable results experienced recently 

 with electromechanical devices arise from i new 

 concept, in experimental design. Traps are used in 

 sufficiently large areas to provide treatment of the 

 total population, or a large segment of the popula- 

 tion, to limit the influence of immigrating inse 

 The favorable results have renewed research inter- 

 esl in practical black-light techniques. This has 

 stimulated research on other forms of electromag- 

 netic radiation as a means of trapping insects for 

 destruction. 



Herbicides 



About the earliest research on selective herbi- 

 cides in the United States took place at the North 

 Dakota agricultural experiment station during the 

 first years of this century organic chemi- 



