Determination of damage status of first generation of cotton bollworm [Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)] on cotton in ？ukurova

In ？ukurova, one of the important pests of cotton is cotton bollworm. There is no economic damage threshold work in our country for the pest, which has a large number of natural enemies and too many chemicals used in its control. For this purpose, the study was carried out in 2004 and 2005 at the ？ukurova Agricultural Research Institute under controlled conditions in cages covered with tulles. First generation of cotton bollworm production was done in the laboratory for releasing cages. The trial cages on 3 meters cotton row, which consist of five densities of larvae (2, 4, 6, 8 and 10 larvae) with untreated control (0 larvae), were established in a randomized block design of 4 replications. It was found that there was an important positive correlation between the number of shed squares and larvae densities. In addition, the economic damage caused by the larvae has been investigated. In both years, as the number of larvae released in the cages increased, the loss of crops increased and linear positive relationships were found between them at high level. According to the obtained equation, the number of larvae that afford the cost of spraying in 2004 was 2.37 larvae/3 meters and 1.56 larvae/3 meters in 2005. The results obtained in this study were found to be very close to the value of 2 larvae/3 meters recommended for the technical instructions. It has concluded that if the results of studies conducted in other countries and the power of cotton to recover for early stage square damage are considered, this threshold should be sustained