Effect of application method on dichlobenil efficacy of hair fescue (<i>Festuca filiformis</i>) in lowbush blueberry

Abstract This study assessed the potential of using dichlobenil to manage hair fescue in lowbush blueberry crops when targeted or broadcast-applied (7,000 g ai ha −1 ) as justification for developing a precision-targeted applicator. A randomized complete block design was used to assess both application methods, and results were compared with industry-standard propanamide (2,240 g ai ha −1 ). Targeted and broadcast-applied dichlobenil in fall 2020 significantly reduced average total tuft density in the nonbearing year (2021) by 75% and 67%, respectively, and in the bearing year (2022) by 61% and 59%, respectively. Broadcast pronamide applications in fall 2020 significantly reduced total tuft density by 84% in the nonbearing year (2021) and 81% in the bearing year (2022). These reductions in total tuft density resulted in average lowbush blueberry yields of 416, 557, 573, and 617 g m −2 for the control, pronamide applications, and targeted and broadcast-applied dichlobenil, respectively. Increases in yield were not significant, though the large variation within the sample is the probable cause. The similarities between targeted and broadcast-applied treatments demonstrate the potential of using targeted dichlobenil. Given the high product cost of dichlobenil at Can$1,873 ha −1 , hair fescue’s non-uniform distribution in lowbush blueberry fields and the lowbush blueberry industry’s overreliance on pronamide, targeted application of dichlobenil has significant potential. This work justifies the development of a mechanized precision-targeted applicator for use in lowbush blueberry cropping systems.