EVALUATION OF CLETHODIM FOR HAIR FESCUE (FESTUCA FILIFORMIS POURR) AND RED FESCUE (FESTUCA RUBRA L.) MANAGEMENT IN LOWBUSH BLUEBERRY (VACCINIUM ANGUSTIFOLIUM AITON) FIELDS IN NOVA SCOTIA

Abstract

Clethodim is a group 1 herbicide that has shown variable efficacy on Festuca spp. and has preliminary research showing suppression of hair fescue in lowbush blueberry during the non-bearing year. Non-bearing and bearing year field efficacy trials were established for hair and red fescue. Greenhouse efficacy trials and field dose response trials were also conducted for hair fescue. Non-bearing and bearing year clethodim applications reduced hair flowering tuft density and tuft inflorescence count (P ≤ 0.0126). Clethodim also reduced leaf number (P < 0.0001) and dry biomass (P < 0.0001) of fescue plants from 15 separate populations in greenhouse trials. Dose response trials indicated the anticipated label rate of 91 g a.i. ha-1 is adequate for suppression of hair fescue. Red fescue was not suppressed in the non-bearing year (P ≥ 0.0966) while bearing year applications reduced flowering stem density by 93.2% (P = 0.0006).