Insecticides sprayed on seedlings of Picea abies during active growth: Damage to plants and effect on pine weevils in bioassay
Abstract:In Finland, the planting period for Norway spruce [ Picea abies (L.) Karst.] has lengthened from spring to summer so that seedlings are also planted during the active growing stage, not only when dormant. On many regeneration sites, there is a high risk of damage by the large pine weevil, Hylobius abietis L., and insecticide treatments are needed to protect seedlings against these weevils. However, all currently available insecticides have been tested and accepted for use only on seedlings that are not growing actively. In this study, actively growing Norway spruce seedlings were treated with three insecticides in mid-June, when the current year's shoot was about 7 cm and unlignified. At this stage of growth, GORI 920® (permethrin) damaged needles and reduced the following year's height growth. Decis Tab® (deltamethrin) and Karate Zeon® (lambda-cyhalothrin) caused no side-effects. All three products were also more or less effective in preventing feeding of pine weevils 1 yr after the treatments. Further studies are needed to investigate the possible harmful effects of insecticides in different stages of growth during the growing season.
Document Type: Research Article
Affiliations: Suonenjoki Research Station, Finnish Forest Research Institute, Suonenjoki, Finland
Publication date: February 1, 2005