Epsilon Archive for Student Projects

Abstract

Over the last couple of years, growers, researchers, advisors and plant protection companies have noticed increasing problems with tortricids in Swedish apple orchards. Since the insecticide Gusathion (azinphosmethyl) has been banned (end of 2008; KemI 2008), a further increase of tortricid populations can be expected. In order to get a picture of species composition and population densities among the tortricids, an inventory of seven species, Adoxophyes orana, Archips podana, Archips rosana, Cydia pomonella, Hedya nubiferana, Pandemis heparana and Spilonota ocellana was made in 11 orchards in southern Sweden (Skåne) in 2008. Population densities were estimated by bud sampling (April 20-25), pheromone trapping (May 5-September 22) and assessment of fruit damage (September 9-12). In all orchards A. podana was the dominating species followed by A. rosana and P. heparana. Trap catches of C. pomonella were generally low, but flight activity was recorded over a comparatively long period of time. Similar flight curves were observed for P. heparana and S. ocellana. Trap catches of H. nubiferana were low at all sites. A. orana only occurred in one of the orchards and exhibited two peaks in flight activity, indicating two generations. Infestation levels of tortricid larvae were low in bud samples, possibly due to sampling being done too early in the season. Average fruit damage was 5%, varying from 1.6 to 21%. The number of pesticide applications and the time for applications varied between the orchards. The common strategy was one application in early May (before bloom) and one in early July. The inventory will be the basis for development of future management strategies and forecasting tools.