Recommendation - pre-planting treatments should be applied to bare-rooted conifer plants using the Electrodyn Sprayer Conveyor system to isolate operators from the insecticide mix and to ensure consistency of treatment. The specially formulated product contains 6.0% alpha-cypermethrin and is used undiluted at a rate of 100 ml per 1000 plants.
The Electrodyn application principle was developed by ICI plc (now Syngenta plc) as a hand held system to treat crops such as cotton in the tropics. It is an electrodynamic (ED) system in which a specially formulated oil-based pesticide passes through a high voltage electric field to create small, highly charged droplets. These are attracted to the nearest earthed surface leading to deposition on both upper and lower surfaces.
The conveyor treatment system was developed by the Forestry Commission, in conjunction with Syngenta, to reduce operator exposure to chemicals and improve plant handling. Plants pass through a spray booth fitted with twin Electrodyn spray heads placed to treat a 150 mm band of plant stem near the root collar. The equipment is designed to maintain a constant flow-rate of the spray liquid. Although the tops of the plants are not treated with insecticide, the efficacy of the treatment is not affected by bridging from site debris.
Treated plants come off the conveyor belt ready for dispatch to the planting site. Before planting, bags should be left open to allow volatile solvents to disperse before the plants are handled.
Since July 2000, treating plants using the Electrodyn Sprayer Conveyor (ESC) has been the recommended method of protecting bare-rooted plants from damage by Hylobius abietis. Approvals for all uses of permethrin in agriculture and forestry were withdrawn in December 2003. Field trials set up during 2002 evaluated the use of alpha-cypermethrin formulated for the ESC using the same standard mix of solvents as Permethrin 12ED. These showed that Alpha C 6ED provides protection from damage by Hylobius abietis for the main part of the first growing season.