Study of leafhoppers [Asymmetresca decedens (Paoli) and Empoasca decipiens Paoli (Homoptera:Cicadellidae)] damages on cotton plants (Gossypium hirsitum L.) in Çukurova region

ABSTRACTMSc THESISSTUDY OF LEAFHOPPERS [Asymmetresca decedens (Paoli) and Empoasca decipiensPaoli (Homoptera:Cicadellidae)] DAMAGES ON COTTON PLANTS (Gossypiumhirsitum L.) IN ÇUKUROVA REGIONMurat ÖLÇÜLÜDEPARTMENT OF PLANT PROTECTIONINSTITUTE OF NATURAL AND APLIED SCIENCESUNIVERSITY OF ÇUKUROVASupervisor: Assoc. Prof. Dr. Ekrem ATAKANYear: 2006, Page: 66Jury: Assoc. Prof. Dr. Ekrem ATAKANProf. Dr. Oktay GENÇERAsist. Prof. Dr. Erdal SERTKAYAIn this study plots were setup with plant groups with different insecticide applications anddifferent leafhopper, (Asymmetresca decedens (Paoli) and Empoasca decipiens Paoli) toinvestigate the population dynamics, effect of different densities of leafhoppers on plantgrowth, yield and yield quality.The higher leafhopper population densities were reached in the and of June in 2004and in the middle of July in 2005.The main population increase lasted 4 weeks and after August population growthdecreased considerably. Population levels in the plant groups and plots with the highestleafhopper densities exceeded economic threshold 1 week in 2004 and 2 weeks in 2005.Different levels of leafhopper populations affected plant growth at different levels. Inthe plots and plant groups with low population densities higher plant lenght, ware pods, balland open ball were recorded; while increase in population levels caused deficiency in plantgrowth.Yield losses were observed as 36-4o %, 50-55 % and 68 % in plots and plant groupswith little, mid-level and high infestation respectively.Two to three times more yield were occured in the spreyed plots compared to the plotswhich are non spreyed and ½ and ¼ dose sprayed in every two week.Different population densities of leafhoppers observed not to effect substantially thecomponents of fiber quality.Key words: Leafhoppers, cotton, damage, Çukurova, Turkey.