Combination effect of spirotetramate and biological and non-biological compounds on some chemical attributes of pistachio leaves and Agonoscena pistacia population

Common pistachio psyllid, is one of the most important pests of pistachio in Iran. In this study, the effect of spirotetramate (SP), salicylic acid (SA), methanolic and n-hexane extracts of walnut husk (MW & NW, respectively), methanolic and n-hexane extracts of dill seed (MD & ND, respectively) and the combined application of spirotetramate with these compounds (SP + SA, SP + MW, SP + NW, SP + MD and SP + ND) were studied on pistachio psyllid population during two years. Distilled water was also considered as control. The amount of secondary compounds (total phenol and flavonoid contents) in pistachio leaves in different treatments was determined. In the first year, the highest percentage of population reduction of pistachio psyllid was observed in combined treatment of spirotetramate and methanolic extract of dill seed (SP + MD) with an average of -91.26 ± 3.21 % and in the second year in methanolic extract of dill seed (MD) with an average of 36.70 ± 8.43% and SP + MD combined treatment with an average of -35.17 ± 17.9%. In both years, the combined use of n-hexanic extract of green walnut husk with spirotratram (SP + NW) reduced significantly the population of pistachio psyllids compared to the use of spirotratram alone. The amount of total phenol and flavonoid compounds in the leaves of pistachio trees treated with the studied compounds showed a significant difference. The highest level of total phenol was obtained in SP + MD treatment (75.48 ± 1.94) that showed significant differences with SP, MD and SP + ND treatments. The results of this study during two years showed that methanolic extract of dill seed in combination with spirotetramate (SP + MD) had the greatest effect in the population control of pistachio psylla nymphs and therefore can be considered in the integrated management programmes of this pest.