بررسی اثر روش آبیاری در شیوع و فعالیت خسارتزایی سوسک کرگدنی طوقه نخیلات Oryctes agamemnon (Col.: Scarabaeidae) در نخیلات آبپخش استان بوشهر

Date palm is the most important crop in Bushehr province which is threatened by many factors especially drought and wood borer pests. One of the most destructive pests is Oryctes spp. which causes severe damage to the trunk and crown of date palm trees. In this study three different irrigation methods namely whole flooding, tape dripping and round flooding were evaluated to determine the occurrence and severity of the damage of Oryctes agamemnon around the crowns of palm date trees in Abpakhsh region in Bushehr province during 2021 to 2023. These orchards are irrigated by the water whose EC is about 4000-5000 μm supplied by Raeesali Delvari Dam. The soil texture is almost loamy clay. The results showed that in orchards whose irrigation method had been eventually changed from whole flooding to dripping method, the infestation to Oryctes agamemnon around the crown after one year was much more severe. The presence of adult and different larval stages of this pest within the crown and root to a depth of 25 cm of palm trees which were irrigated by dripping method compared to whole flooding or round flooding methods can strengthen the probability of the impact of irrigation method upon the occurrence and activity of Oryctes agamemnon around the crown. It seems that sudden changing the whole flooding method of irrigation to the dripping method in palm orchards causes the reduction of humidity around the root and crown and simplifies the establishment and damage of the pest while the whole flooding method of irrigation supplies the humidity around the crown and root and makes limitation for establishment and damage of the pest. For more evaluation, the irrigation method of few trees which were affected from the pest changed to whole flooding or round flooding method. In these trees, the activity and damage of the pest were significantly reduced around the crown and root. So, considering the damage of this pest in one hand and the scarcity of water for whole flooding irrigation of date palm orchards in Bushehr province in the other hand, it is recommended that best irrigation method in infected regions is round flooding or dripping (type bubler) in round flooding which optimizes the water use and reduces the activity of Oryctes agamemnon around the crown and root of date palm trees. In addition to changing the method of irrigation, light traps for mass trapping of adults, pruning the base of fronds for eliminating the ecological niche of larval, pupal and adult stages of the pest, nutrition of the trees and spraying the crown by 2.5/1000 Malathion after gentle irrigation as IPM program, is effective in reduction of the population and injury of the pest.