Towards a system of non-chemical flower thrips control in strawberry production

Different flower thrips species (Thrips major/T. fuscipennis, Frankliniella intonsa) feed on strawberry fruit causing severe production losses. Because of the zero tolerance in The Netherlands for thrips damage the pyrethroid deltamethrin (Decis) is sprayed during blooming. Since 2013 there is a restriction in number of sprays and spraying during blooming is prohibited because of the negative effect on pollinators and natural enemies. A robust integrated pest management system could reduce chemical sprays significantly. Reducing residue levels enhance the positive image of fruit consumption. During the summers of 2012 and 2013 an IPM strategy for control of flower thrips was tested in strawberry field trials ('Elsanta'). Biological control was enhanced by the predatory bug Orius majusculus. In 2012 and 2013 the effect of mulching by white plastic film was also studied. To lure and retain Orius bugs in the crop, dispensers with the attractant methyl salicylate and Alyssum plants were placed in treated plots. From mid-July control of flower thrips by natural enemies was comparable to chemical control with deltamethrin. Good results in reducing thrips larvae in the flowers were also obtained using white plastic mulch. A combination of measures could lead to a robust system of non-chemical flower thrips control in strawberry in the near future.