Control of eastern spruce and Cooley spruce gall aphids with soil-applied systemic insecticides.
Field studies were carried out in Ohio during 1971-75 on the effectiveness of soil applications of systemic insecticides for the control of the gall-causing phylloxerids Sacchiphantes abietis (L.) (Adelges abietis) and Gilletteella cooleyi (Gill.) (A. cooleyi) on Norway spruce (Picea abies), white spruce (P. glauca) and Colorado blue spruce [P. pungens]. Application of insecticide granules (containing disulfoton, carbofuran or aldicarb) in mid-April (in 1973-75), about 2 weeks before fundatrices began oviposition, prevented the formation of galls on trees infested with S. abietis. Similar treatment in mid-May (in 1972) or mid-June 1971) failed to prevent gall formation or to kill the adelgids within the galls. Application of aldicarb to broken ground at the drip-line of trees at a rate of 2.8 g toxicant/2.54 cm of trunk diameter 30.48 cm above ground controlled S. abietis, whereas carbofuran and thiofanox (Dacamox) were effective only when applied at 5 times this rate. Aldicarb and carbofuran were similarly effective against G. cooleyi.