Raspberry leaf and bud mite (Phyllocoptes gracilis) in Serbia: the pest status and control options

Raspberry leaf and bud mite Phyllocoptes gracilis (Nal.) is the most important secondary pest of raspberry in commercial production plantations in Serbia. It is widespread an all production areas. The damage is manifested by changes on leaves (chlorotic, mottling, malformation of leaf hairs) and on fruits (irregular fertilization and fruit development, uneven coloration of some drupelets, growth stagnation, uneven ripening). Recent studies suggest a possible connection between leaf and bud mite and a new virus of raspberry (raspberry leaf blotch). The adults overwinter in one-year shoots, and several generations are produced on the back side of a leaf during vegetation period. Raspberry leaf and bud mite can cause a significant damage on raspberry, if control measures are not carried out. Organophosphates and pyrethroids, insecticides with a wide activity spectrum, which were the core in raspberry protection from main insect pest species – and which also express acaricidal activity – partially resolved this issue. Besides them, endosulphan was widely used, an organochlorine substance known for its high efficacy in eriophyoid control. Currently, most of these substances are withdrawn from use or are facing withdrawal procedure. Except abamectin and milbemectin, insecticides recommended instead of organophosphates and other substances of older generation, do not have significant activity agains mites. Besides this, P. gracils populations often reach high abundance and after harvest, in dryer years a more significant presence of two-spotted spider mite, Tetranychus urticae, is usually recorded, therefore acaricides have to be included in raspberry protection program. Among acaricides of older and newer generation, which are still available on the market, propargite, organotin compounds (cyhexatin, fenbutatinoxide), hexythiazox, benzoylureas (flucycloxuron, flufenoxuron), proved to be efficient in eriophyoid control. Among acaricides which occurred on the market in the last two decades, a significant activity on eriophyoids exhibit METI acaricides (fenazaquin, fenpyroximate, pyridaben, tebufenpyrad), diafenthiuron, chlorfenapyr, tetronic acid derivatives ( spirodiclofen, spiromesifen). Sulfur and azadirachtin, pesticides compatible with organic production, proved to be highly efficient. When selecting acaricide, it is of high importance to alternatively apply substances with different modes of action. However, the choice is significantly narrowed by various legal concepts, such as implementation of 91/414 Directive, which drastically reduced acaricide portfolio in EU, including a number of compounds with good eriophyoid control potential.