Impact of the methods of cultivation on the size of pest population in raspberry plantations in Latvia

Abstract: Over the vegetation seasons of 2011 and 2012, trials were carried out in Latvian State Fruit-Growing Institute (LSFGIL) to observe raspberry pests and their population levels in raspberry plantations under FGV (3 sections, up to ground) and Haygrove (3 sections, above ground 1 m) type high tunnels as well as under opened-field cultivation. Five economically significant pests were detected under FGV and Haygrove type high tunnels – strawberry blossom weevil Anthonomus rubi Hbst., raspberry beetle Byturus tomentosus Fabr., raspberry cane midge Resseliella theobaldi Barnes., two-spotted spider mite Tetranychus urticae Koch and thrips Thripidae gen. sp. There were no significant differences in pest level and damage by A. rubi neither under FGV and Haygrove type high tunnels nor in the opened-field cultivation. The highest levels of damage on raspberry sprouts (8-10%) under FGV type high tunnels were caused by R. theobaldi, however this was is not statistically. The highest levels of T. urticae population were seen under FGV and Haygrove (on average 2.4-2.5 individuals per leaf), in comparison with opened-field cultivation where no two-spotted spider mites were not statistically. After assessing raspberry yield in LVAI, it was established that the highest levels of damage by B. tomentosus were seen under FGV type high tunnels, where raspberry beetle had damaged 12.4% of the yield. Also, thrips (Thripidae gen.sp.), pests currently rarely seen in raspberry plantations of Europe and Latvia, were detected in the field trials, damaging from 0.4 to 3.4% of the yield. Further studies on the importance of thrips on raspberry yield should be carried out.