Hoeg, Lienna2025-11-272025-11-272025-11-27https://hdl.handle.net/10222/85537Narrowleaf goldenrod (Euthamia graminifolia) has emerged as a major perennial weed challenge in wild blueberry (Vaccinium angustifolium) production in Nova Scotia, impacting crop management and yield quality. This thesis investigated the phenological development of E. graminifolia and evaluated integrated strategies for its control. Predictive models based on growing degree days were developed to accurately describe shoot emergence and flowering timing, enabling growers to better schedule post-emergence management. Narrowleaf goldenrod ramet emergence began at 25-71 GDD, and continued to 1,047-1,665 GDD across all study sites. Narrowleaf goldenrod ramets were observed at the flowering bud stage between 710 and 871 GDD (June 21 – 28), and approximately 90% of emerged ramets reached the flowering bud stage between 1303 – 1956 GDD (July 17 – August 24). Emerged ramets began flowering between 1418 – 1626 GDD (July 30 – August 7), and approximately 90% of emerged ramets were flowering between 1992 – 2225 GDD (August 27 – September 12). Cumulative E. graminifolia seedling emergence ranged from 2.4 ± 0.8 to 4 ± 1 seedlings m-2, respectively, and seedling density from soil core samples ranged from 0.02 ± 0.01 to 6.92 ± 1.80 seedlings per core. Seedbank and seedling recruitment studies indicated limited establishment of new plants through sexual reproduction in managed fields, highlighting the necessity of focusing on established populations. Herbicide field trials were established across eleven commercial lowbush blueberry fields in Nova Scotia between 2019 and 2021 to evaluate early-POST, late-POST, and post-harvest, pre-pruning herbicide applications. These studies identified mesotrione-based treatments and targeted fall applications as the most effective methods for long-term suppression with minimal crop injury. The research supports renewed registration efforts for key herbicide programs and provides practical recommendations for sustainable weed management, helping Nova Scotia blueberry growers address the threat of an increasingly dominant, competitive weed species.enWeed ManagementWild BlueberryLowbush BlueberryNarrowleaf GoldenrodEuthamia graminifolia L.Vaccinium angustifolium