Determination of economic injury level of the citrus cushion, Pulvinaria aurantii (Hem.: Coccidae) in conventional citrus orchards

The orange Pulvinaria scale, Pulvinaria aurantii (Cockerell) is the most important pest of citrus in Mazandaran, Iran. The calculation of economic injury level is essential for the appropriate decision to Pest control. The economic injury level (EIL) of P. aurantii on Washington navel orange was studied during two years (2011 and 2012) in Sari (north of Iran). In the first year, six treatments of different densities of pest ovisacs (0, 1, 4, 7, 10 and 13) and each treatment with 8 replications and in the second year, five treatments (0, 5, 10, 15 and 20), each treatment with 7 replications on the leaves were evaluated in a completely randomized design (CRD). Economic injury level (EIL) was calculated as 133, 125, 110 and 131 ovisacs per branches with an average number of 7.1, 6.7, 5.9 and 7 fruits for the first generation of 2011 and 242, 228, 201, and 238 ovi sacs per branches with an average number 7.1, 6.68, 5.88 and 7.01 fruits for the first generation of 2012, as well as 203, 191, 168 and 200 ovisacs per branches with an average number 7.1, 6.68, 5.88 and 7.01 fruits for the second generation of 2012, for ethion, chlorpyrifos, buprofezin and diazinon pesticides, respectively.