Effect of early season insecticide use and square removal on fruiting patterns and fiber quality of cotton

The effect of early-season cotton, Gossypium hirsutum L., square loss and insect control (primarily thrips, Frankliniella occidentalis (Pergande)), on the ability of cotton plants to replace lost fruit as well as maintain lint quality was examined in several field trials of differing experimental design in Arizona during 1986-1987. All trials indicated some degree of compensation for damage to fruiting structures and yield depending upon the timing and plant growth stage. Significant differences in yield were detected only in plots that had squares removed 4 wk after initiation of square production. Most measures of cotton quality were similar among treatments. No differences in fiber strength, elongation, or any color or trash index were calculated for any test. Only a few significant differences between treatments were detected in length, micronaire, or uniformity. However, differences among treatments in all tests were small and all values within a test were still within the same relative range, either "average" or just below "average" range. The treatment with squares removed at 4 wk after square initiation had shorter fiber lengths than those with squares removed early or no removals. 'Deltapine 90' cotton treated with aldicarb at pinhead square had higher micronaire than aldicarb-treated 'Deltapine 77', but there were no differences between treated and untreated plots. Treated 'Deltapine 90' had higher uniformity than untreated 'Deltapine 90', but there were no differences between cultivars or between treated and untreated 'Deltapine 77'. Cotton from plots treated with phorate at planting had higher uniformity ratios than cotton from either aldicarb-treated or control plots. Comparisons of the results of this study are made with those of other regions. Possible factors producing different results are discussed.