Application of deltamethrin for spraying or dipping to protect Scots pine seedlings against Hylobius abietis L. and logs against Tomicus piniperda L.
Efficiency of protecting Scots pine [Pinus sylvestris] seedlings in Poland against Hylobius abietis, the large pine weevil, using deltamethrin (Decis 2.5 EC) was assessed. Seedlings were either dipped before planting, or sprayed after planting in Lochow and Myszyniec forest districts. Assessment of beetle damage and rate of degradation of the insecticide proved that dipping before planting was more effective than spraying afterwards. Similarly, experiments on the use of deltamethrin to control Tomicus piniperda, the pine shoot beetle, in felled and stacked pine logs (in forests or in timberyards) were also carried out. Spraying of logs took place after the late frosts (in early spring) and during the first days of swarming (about 3 weeks later). Persistence of the insecticide was found to be good in bark, and therefore timing of spray treatment was not critical to the swarming period. Treatment up to 2-3 weeks prior to swarming gave effective protection.