Economic threshold studies of the boll weevil (Anthonomus grandis) in West Tennessee

Experiments were carried out at Ames Plantation, Grand Junction, Tennessee, and Milan Field Station, Milan, Tennessee, during the cotton growing seasons of 1975 and 1976 to better define the economic threshold level of the boll weevil, Anthonomus grandis (Boheman). Chemical con-trol efforts were begun at levels of 10, 20, and 30 percent fruit infestation. Boll weevil activity was monitored and recorded throughout the growing seasons. Experiments were set up in a randomized complete block design with varying replications depending upon the location of the test. The Milan test in 1975 showed a high negative correlation between levels of boll weevil infestation at initiation of chemical treatment and yield of seed cotton. The test indicated that, with a base yield of 20.595 cwt. per acre, every unit (percent) increase in boll weevil damage there was a decrease in production of .2151 cwt. per acre. Three tests showed no significance between the yield of seed cotton per acre and percent boll weevil damage at the initial chemical application in plots sprayed at lower damage levels as compared to plots sprayed at higher damage levels.