Boll Weevil 1 : Relationship of Predicted vs. Observed Peaks of Populations to Squaring Rates of Two Cotton Cultivars 2

Abstract

From 1973 to 1975, two varieties of cotton, Stoneville ST-213, a standard cultivar, and Tamcot SP-37, a short-season cultivar, planted at ca. 50,400 plants/ha, in river silt in the Lower Rio Grande Valley of Texas, were sampled for adults of the boll weevil, Anthonomus grandis grandis Boheman, and boll weevil larval damage to squares. The predictions of 2 models for the peak emergence of adults of 4–5 generations of boll weevils was then compared to the actual times of peak emergence of weevils in the field. A good relationship was found between the number of days (0–3 days) when adults of F2 were actually observed in cotton and when they were predicted based on the time for 98% adult emergence. From computed cumulative squaring, 50% of the squares occurred 4 and 9 days earlier on SP-37 than on ST-213 in 1973 and 1974, respectively, and populations of weevils were greater in SP-37 than in ST-213 during 2 of the 3 test yr. Reliable data were accumulated from the sampling of 0.25% of the plot area measuring 204 m2.