ABSTRACT In conventional low‐stem pome‐fruit orchards, tree strips are kept weed‐free during the growing season through two to four herbicide applications per year. However, it remains unclear whether season‐long control is necessary in mature orchards. This study delineated the critical weed‐free period (CWFP) in mature Belgian pear and apple orchards, focusing on marketable yield and vegetation dynamics. The CWFP started at budbreak (BBCH07) to lower the risk of frost damage, and its end was defined by weed release at key phenological stages: end of flowering (BBCH69), start of fruit development (BBCH71), second fruit fall (BBCH73), 50% fruit size (BBCH75), 80% fruit size (BBCH78) and harvest (BBCH87; season‐long weed‐free control). Weed control was achieved by glyphosate applications. Across multiple years and locations, fruit yield (kg tree −1 , fruit number and individual fruit weight), fruit quality (size distribution, soluble solids, firmness, nutrient concentrations), end‐season weed cover and composition were recorded. Maintaining a weed‐free tree strip through bloom (until BBCH69) was sufficient to preserve yield and quality across locations and years. Vegetation responses revealed a trade‐off: early weed release (BBCH69–71) increased weed biomass and favoured clonally reproducing perennials, whereas late release (BBCH75–78) produced a low‐biomass, bryophyte‐dominated cover with limited competitive pressure. In mature orchards, weed management can be more flexible. Control can be concentrated between budbreak and the end of bloom, complemented by post‐bloom, needs‐based interventions when troublesome perennials occur. Developing cost‐effective, input‐efficient programmes will be crucial for maintaining yield and quality whilst tempering the invasive perennials in the tree strip.
Dutordoir et al. (Sun,) studied this question.
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