Influence of the two herbicides Gesagard and Triflan application on some cotton pests in Abu–Ghraib region, Baghdad


Field experiment was undertaken to evaluate the influence of the herbicides Gesagard (Prometrin) and Triflan (Trifluralin) on some insect pests and mites infesting cotton in Abu – Ghraib during the growing season of 2002. Results showed that the use of herbicides or hand weeding had relatively similar effect on whitefly Bemisia tabaci Genn. Population which was the most dominating species over other sucking insect pests. While the highest population densities of the thrips, Thrips tabaci Lind. and the leafhopper Asymmetrasca decedents (Poali) were respectively 1.8 and 0.8 individuals/5 leaves recorded on cotton plant of Triflan treatment .Results have also indicated the presence of the two spotted spider mite Tetranychus urticae Koch. on cotton plants of all treatments . The lowest mean of population density was 3.1 individuals/5 leaves recorded for Gesagard treatment followed by hand weeding with mean of 5 individuals /5 leaves. while the highest mean was 11.8 individuals /5 leaves recorded on plants in the control treatment. As for the bollworms , results showed that the spiny bollworm Earias insulana Boisd. was the dominating species , however, infestation was relatively low and variable on all treatments . Means of infestation percentages for Gesagard and Triflan were 6 and 7.1% respectively .While infestation percentage for the control treatment was 7.3 % .Therefore ,the variation of infestation on the different treatments may indicate no direct effect of the herbicides used in this experiment on insect pests or spider mites in cotton fields. The use of herbicides or hand weeding would have indirect effect on these pests through their influence on cotton plants to improve tolerance and defenses mechanisms against pest infestation.