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Spring dead spot (SDS), caused by Ophiosphaerella spp., is among the most damaging diseases to hybrid bermudagrass (Cynodon dactylon × transvaalensis) in areas where winter dormancy occurs. Management strategies that aid in turfgrass recovery from SDS damage have not been widely studied. An experiment was conducted in Blacksburg, VA, in 2019 and 2020, to determine the influence of various cultural practices on bermudagrass recovery from SDS damage. Fertility and cultivation were applied in the late spring/early summer, which is earlier than normal for cultivation practices for bermudagrass, to test their effectiveness in aiding bermudagrass recovery from SDS damage. The main effects of fertility and cultivation were arranged in a 2 × 3 factorial design with vertical mowing, solid-tine aerification, and no cultivation applied with urea (48.8 kg⋅ha⁻¹ N) sprayed at trial initiation and 2 weeks later or without urea. Plots were assessed for the percent of SDS throughout the study. Data were analyzed as the percent change relative to the initial assessment to measure bermudagrass recovery. The main effect of fertility increased bermudagrass recovery from SDS damage in both 2019 and 2020. The main effects of vertical mowing and solid-tine aerification reduced bermudagrass recovery from SDS damage in 2020. These data suggest that two properly timed nitrogen fertilization applications at 48.8 kg⋅ha⁻¹ optimized bermudagrass recovery from SDS damage, whereas late spring/early summer cultivation without fertility may inhibit bermudagrass recovery.

Bermudagrass is a warm-season turfgrass species widely used for sports fields, home lawns, and golf courses. Ultradwarf bermudagrass has been used for golf course greens, but its quality declines with abiotic stresses. This 2-year study was designed to investigate if foliar applications of seaweed extract-based biostimulant Utilize® could improve ultradwarf bermudagrass photosynthetic function, nitrate reductase activity, root growth, and root function while under heat stress and drought stress conditions. Utilize® was applied to ultradwarf bermudagrass canopy at 0, 88, 117, 175, and 234 μL⋅m⁻². Two weeks after the initial application of Utilize®, bermudagrass was subjected to heat (40/36 °C, day/night) and drought stress (40–50% evapotranspiration replacement) for up to 42 days. Heat stress and drought stress caused decline of the turf quality. Foliar application of Utilize® at 117, 175, and 234 μL⋅m⁻² biweekly consistently improved turf quality and leaf color ratings and increased leaf chlorophyll and carotenoid concentrations, net photosynthetic rate, nitrate reductase activity, and root growth and viability. On average, Utilize® at 117, 175, and 234 μL⋅m⁻² increased turf quality ratings by 9.1%, 12.1%, and 10.6%, respectively, net photosynthetic rates by 32.4%, 45.0%, and 35.0%, respectively, and nitrate reductase activity by 16.7%, 18.8%, and 14.6%, respectively, compared with the control. Utilize® at 117, 175, and 234 μL⋅m⁻² increased the root biomass, root length, surface area, and root volume compared with the control. Utilize® at 88, 117, 175, and 234 μL⋅m⁻² increased root viability by 46.2%, 73.1%, 88.5%, and 74.4%, respectively, relative to the control. The results of this study suggest that seaweed extract-based biostimulant Utilize® improves nitrogen metabolism, photosynthetic function, root growth, and root viability. Foliar application of Utilize® at rates between 117 and 175 μL⋅m⁻² biweekly can be considered an effective approach to improving ultradwarf bermudagrass performance under heat stress and drought stress environments.