Integrated management approaches for controlling lesser clover leaf weevils in red clover for seed production.

Non-Peer ReviewedSingle-cut red clover (Trifolium pratense L.) is an important forage seed crop in Western Canada due to its winter hardiness and economical value. However, infestation of lesser clover leaf weevil (LCLW) (Hypera nigrirostris F.) in red clover fields can lead to drastic yield losses (up to 80%). Moreover, limited data is available to support relationships of clover stand density and pest pressure. The aim of this research is to evaluate the effectiveness of different insecticidal materials in controlling LCLW and their impacts on the pollinator community, along with determining an optimal seeding rate for seed production. Four different insecticide methods Decis (Deltamethrin), Exirel (Cyantraniliprole), Voliam Xpress (Lambda-cyhalothrin & chlorantraniliprole) and untreated control, were compared for control of LCLW. Six different seeding rates (0.5, 2.5, 4.5, 6.5, 8.5, 10.5 kg/ha) are being compared for the b est seed yield over three years experiment. Pest pressure data on the LCLW in red clover fields was tracked over the 2018 and 2019 growing season in five locations, mostly in North Saskatchewan. Concentration of red clover fields and consequently red clover pests were greater in northern SK. The preliminary analysis suggests that both Decis, Exirel and Voliam Xpress can significantly reduce the LCLW larvae pressure in comparison with the control. All chemicals tend to suppress LCLW numbers from 1 to 6 days after treatment. In contrast, LCLW larvae numbers increase in 12 days after Exirel treatment whereas in Decis and Voliam Xpress the pressure remains constantly low. Rearing LCLW larvae on treated plants in lab conditions showed similar results in 10 days

Assessing chemical control options and their effects on lesser clover leaf weevil, red clover pollinators and evaluating red clover seeding rates for optimal seed production and N fixation in Saskatchewan, Canada

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