Browsing by Author "Booth, Jordan Christopher"

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    Impact of Management Practices on Cold Tolerance of Ultradwarf Bermudagrass Putting Greens
    Booth, Jordan Christopher (Virginia Tech, 2022-04-15)
    Low temperature injury is among the greatest challenges facing golf courses with ultradwarf bermudagrass (UDB) (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) putting greens in Virginia. This research focused on the impact of turf covers, fungicide programming, core aeration, and trinexapac-ethyl (TE) on UDB cold tolerance, winter quality, and cold de-acclimation (CD). Our results indicate that the use of turf covers significantly increased UDB canopy and soil temperatures when air temperatures were below -3.9°C. Air gaps under covers and the use of double turf covers increased soil and canopy temperatures compared to single covers alone in some instances, but results were inconsistent. Late fall and early winter fungicide applications of chlorothalonil and azoxystrobin improved UDB quality throughout winter dormancy and spring green up. The addition of a pigmented phosphonate significantly improved winter and spring UDB quality. The addition of acibenzolar-S-methyl to fungicide programs did not improve winter UDB quality or spring green up. Summer core aeration programs were evaluated for their impact on spring green up, turfgrass quality, surface firmness, and moisture retention. Spring UDB green up was improved incrementally as surface disruption increased. Treatments with 20%, 15%, and 10% surface disruption produced higher color vs treatments with lower surface disruption. Surface firmness and volumetric water content of UDB were impacted by construction method but were not significantly impacted by core aeration programs. Field research revealed that 'fall only' and 'fall and winter' TE applications improved UDB quality but only 'fall and winter' delayed UDB premature CD in early spring when UDB can be susceptible to low temperature injury. Growth chamber studies evaluated the impact of TE on UDB cold tolerance to -9.4°C x time duration. Regression analysis predicted a 50% mortality exposure point for UDB under TE treatments of 9.84 hours at -9.4°C (r2=0.836) compared to 11.38 hours at -9.4°C (r2=0.671) for non-treated UDB during cold acclimation. Winter and spring scenarios resulted in delayed CD under TE but no differences in cold tolerance when exposed to -9.4°C. Together, these results increase our understanding of the impact of management practices on UDB winter quality, CD, and low temperature injury.
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    Investigating Spring Dead Spot Management via Aerial Mapping and Precision-Guided Inputs
    Booth, Jordan Christopher (Virginia Tech, 2018-06-08)
    Spring dead spot (SDS) is the most destructive disease of bermudagrass (Cynodon spp.) in Virginia. SDS infects bermudagrass in the fall with symptoms appearing in the spring when dormancy breaks. Patches are sporadically distributed but generally reoccur in the same location. Chemical control options are expensive with inconsistent results. Our objectives were to develop SDS incidence maps, investigate methods to analyze these maps, and evaluate suppression efficacy of incidence-map-based chemical applications. Methods were developed to build SDS incidence maps in 2016 and 2017. 2016 SDS incidence maps were compared for spatial accuracy to Digital Orthophoto Quarter Quadrangle (DOQQ), ground-validated differential GPS coordinates, and to 2017 SDS incidence maps, with average deviations of 1.3 m, 1.6 m, and 0.1 m, respectively. Digital Image Analysis (DIA) of aerial maps was compared to a point-intersect method for validation with a significant linear relationship (r2 = 0.77, P ≤ 0.0001). In the fall of 2016 and 2017, a site-specific penthiopyrad (SSP) treatment was evaluated against blanket, full-coverage applications of penthiopyrad (BP) and tebuconazole (BT), and an untreated control. Treatments were compared using DIA, post-treatment SDS patch count (PC), and SDS patch reduction (PR). Across all three metrics, the penthiopyrad treatments were statistically superior to both the tebuconazole and untreated. SSP compared favorably to BP for DIA, but BP had 2.57 fewer PC (LSD = 2.05) and a greater PR by 2.58 (LSD = 2.55). SSP using SDS incidence maps required 51% less fungicides in 2016 and 65% less in 2017 when compared to BP.