تاثیر تاریخ کشت بر جمعیت تریپس و سفید بالک پنبه در دزفول

Cotton cultivation in Dezful faces significant challenges due to severe infestation by sucking pests and the complexities associated with their control. To study the population changes of two sucking pests, the cotton thrips (Thrips tabaci) and the cotton whitefly (Bemisia tabaci), under different planting dates, an experiment was conducted with 12 varieties across three planting dates in 2023. The experiment utilized a split-plot design within a randomized complete block design framework with three replications. Varieties were the main factor, and planting dates (March 11, March 19, and March 30, 2023) were the sub-factors. Thrips density was recorded weekly from the seedling stage to the end of flowering by shaking 10 randomly selected cotton plants from each plot over a white sheet, collecting the thrips, preserving them in 75% alcohol, and counting them in the laboratory. The density of immature whiteflies was determined by sampling 5 young leaves from 10 plants per plot and counting eggs and nymphs in the laboratory. Adult whitefly density was assessed weekly using four yellow sticky traps per 1000 square meters. Analysis of variance was performed using the split-plot design with SAS software, and means were compared using the Tukey method. The results showed that the planting date significantly affected the population of sucking pests at the 5% level, with the lowest pest populations observed on the March 11 planting date compared to the other dates. Additionally, the average number of adult whiteflies in a 2x2 cm square was 35, and the number of whitefly nymphs per leaf was 2.3 ± 0.05. The adult whitefly population was significantly higher than the nymph population per leaf. Furthermore, the "Perto" variety showed the highest thrips count per leaf at 1.75 ± 0.2, while the "Mai 344" variety had the lowest at 0.8 ± 0.05. These findings highlight the important role of planting date and variety in managing cotton pest populations in the region.