Control of Arboreal Aphids with Systemic Insecticides, 1992

Treatments were applied on 14 Aug or 17 Aug to individual tree replicates for mature street trees (50-70 cm DBH) in Beverly Hills, CA, according to a RCB design with 3 replicates per tree species. Each treatment was applied using standard injection techniques: one pressurized injection unit was inserted into a pre-drilled hole at 10 cm above ground for every 15 cm of breast-height trunk circumference, then the internal seal was broken. Aphid counts were made from foliar samples collected from a hydraulic lift. Pre-treatment samples were obtained 14 Aug from 2 of the 3 ash replicates. Infested leaves were paired with similar infestations which were marked for later sampling. Post-treatment counts were made on 9 Sep from all 3 ash replicates, however, measurable elm leaf aphid populations were found in only one replicate of the elm study.