Fertilizer and Fluazifop-P Inputs for Winter Bentgrass- (Agrostis hyemalis) Infested Lowbush Blueberry Fields

Abstract

Winter bentgrass is a common, shallow-rooted perennial weed of lowbush blueberry fields. This unique production system is typically managed on a biannual cycle with blueberry shoot growth and floral bud development occurring in the first year (vegetative year) and berries harvested in the second year (crop year). An experiment was conducted in two commercial blueberry fields to determine the impact of 0, 143, or 286 kg ha−1of 14–18–10 fertilizer applied in the vegetative year, and fluazifop-P applications in the vegetative, crop, or both years of the biannual production cycle, on winter bentgrass and blueberry growth and yield. Fluazifop-P tended to reduce winter bentgrass biomass at both sites and the vegetative year-herbicide applications had a greater impact on winter bentgrass ground cover than crop-year applications. Total weed biomass following fluazifop-P applications was reduced in the vegetative year but not the crop year due to an increase in broadleaf weed biomass. Grass biomass tended to increase with fertility inputs in the vegetative year. In all years and sites, the application of fertilizers without herbicides increased grass biomass compared to the use of fertilizers combined with herbicides. Blueberry floral bud numbers per stem, flowers per stem, and berry yield tended to increase with vegetative year applications of fluazifop-P, although differences were not significant. These data indicate that winter bentgrass management is best achieved with herbicide applications in the vegetative year and this might result in yield increases, especially if broadleaf weeds also are adequately controlled.