Concentração eficiente e econômica de caulim para a proteção de algodoeiro contra o bicudo

Abstract

The objective of this work was to determine the most effective and economical kaolin concentration to protect cotton against the injuries caused by the boll weevil (Anthonomus grandis). A randomized complete block design was used with five treatments of kaolin spraying at the following concentrations: 20, 40, 60, 80, and 100 g L-1. The following parameters were determined: percentage of punctured squares with oviposition by boll weevil females; the amount of kaolin residues on leaves and bracts of cotton square; average yield; and the cotton net income per hectare, measured from the weighing of cotton lint with seed. The percentages of oviposition-punctured squares ranged from 13.6 to 30.8%; kaolin residue, deposited on cotton leaves, ranged from 0.0010 to 0.0034 mg mm-2, and on bracts, from 0.0010 to 0.0034 mg mm-2; production ranged from 348.1 to 717.8 kg ha-1; and the net revenues from cotton ranged from R$ 1,033.88 to R$ 2,098.86 per hectare. The most efficient kaolin concentrations for cotton protection against damage caused by boll weevil are those of 60, 80, and 100 g L-1; however, the concentration of 60 g L-1 is the most economic one.