Evaluation of terbacil-based herbicide treatments for hair fescue (Festuca filiformis) management in lowbush blueberry

Abstract

AbstractHair fescue is a common tuft-forming perennial grass weed that reduces yields and hinders mechanical harvest in lowbush blueberry fields. PRE terbacil applications traditionally controlled hair fescue but currently only provide suppression in most fields. Terbacil use has not, however, been evaluated in conjunction with other currently registered herbicides in lowbush blueberry. The objective of this research was to evaluate a range of terbacil-based herbicide treatments for hair fescue management in lowbush blueberry. The experiment was conducted at three lowbush blueberry fields in Nova Scotia, Canada. Spring nonbearing-year terbacil applications (2,000 g ai ha–1) exhibited variable efficacy on hair fescue with reduced total tuft density at one site and reduced flowering-tuft density and flowering-tuft inflorescence number at two sites. Suppression was limited to the year of application only. Terbacil followed by (fb) foramsulfuron (35 g ai ha–1) did not improve suppression. A terbacil tank mixture with glufosinate (750 ai ha–1), however, reduced flowering-tuft density and flowering-tuft inflorescence number at each site and reduced total tuft density at one site, suggesting improved suppression with terbacil + glufosinate relative to terbacil alone. Terbacil + glufosinate fb foramsulfuron gave additional reductions in total tuft density at two sites and reduced bearing-year flowering-tuft density at two sites, indicating that hair fescue suppression with this herbicide combination extends into the bearing year. Although less effective than the industry standard pronamide applications, terbacil + glufosinate or terbacil + glufosinate fb foramsulfuron could be used as part of a weed management program for hair fescue in lowbush blueberry.