تاثیر مراتع و بافت خاک بر جمعیت و خسارت زنجره Psalmocharias flava در باغ‌های بادام چهارمحال و بختیاری

Psalmocharias flava Delabola 1970 is one of the pests of almond and peach orchards in Chaharmahal va Bakhtiari province. Adult insects appear periodically in high population and cause damage by laying eggs on the young branches (especially in nurseries). Pest nymphs also settle on the root of the host and feed from plant sap. This study was carried out in Saman and Ben counties of Chaharmahal va Bakhtiari province during the years 2019 to 2023. In order to investigate the effect of rangeland on the population and damage of the pest, three almond orchards (at the same age) with different distances of 100, 500 and 1000 meters from the rangelands were selected in each area, and the number of exit holes (per square meter), the number of nymphal exuviae (on each trunk) and the percentage of infested branches were compared. Moreover, to investigate the effect of soil on the population density and activity of the pest nymphs, soil samples (from 0 to 30 cm depth) of the studied orchards were compared in terms of soil texture and physical properties. Our results showed by increasing the distance from the rangeland, the number of nymph exit holes (per m2), the number of last instar exuviae, and the percentage of the infested branches were significantly decreased. The average number of nymphal exit holes (in m2) in both studied areas at distances of 100, 500 and 1000 meters from the rangelands were recorded 48.07 ± 2.07, 28.1 ± 1.64 and 16.55 ± 1.24 respectively . The same trend was observed in the number of nymphal exuviae (on each trunk). The average number of of nymphal exuviae (per tree) was calculated as 63.75 ± 5.99, 39.75 ± 3.43 and 21.8 ± 1.06, respectively. Moreover, the texture and physical properties of the soil greatly influenced on the activity of P. flava nymphs. The soils of heavy infested areas had loam or loam-clay texture. Compared to sandy soils, they create more suitable conditions for the creation of nymph nests, and compared to clay soils (heavy texture), have more suitable conditions for the movement and activity of nymphs. Avoiding the rangeland destruction and not constructing orchards in these places effectively reduce the pest population and damage.