ABSTRACT

Studies were conducted to assess the effects of conventional and conservation tillage on boll weevil, Anthonomus grandis grandis Boheman, mortality in postharvest cotton fields. Samples taken just before harvest, indicated that the number of fallen fruiting structures per m², the number of infested fruits, and the number of fruits containing live boll weevils were sig-nificantly higher in conventionally tilled fields than in conservation tillage fields. By 7 days postharvest, boll weevil mortal-ity in conservation tillage fields was 12.4-fold higher in infested squares, which remained on the soil surface, than in those buried in conventional tillage fields. The major factor responsible for boll weevil mortality immediately after harvest in con-servation tillage plots was high soil-surface temperatures. Mortality of boll weevils in small or medium size bolls (10-15 mm in dia) on the soil surface was significantly lower than in squares, presumably because the bolls provided better insolation from the high temperatures. Mortality in the large laboratory-infested bolls (>20 mm in dia) was higher than in small or me-dium sizes bolls presumably because development in large bolls is more difficult.