This research addressed the identification and distribution of selected ERI fungi within two greens at Mississippi State University Golf Institute using novel molecular methods, spatial relationships of fungal distribution and turf health assessments, and fungal sensitivity to selected fungicides. A complex of ERI fungi was identified in both greens. Gaeumannomyces graminis, Gaeumannomyces sp., and Candidacolonium cynodontis were randomly distributed based on spatial autocorrelation in both green samplings, while Magnaporthiopsis cynodontis clustered in Green 2 for both samplings and in Green 12 of the 2018 sampling. Clustering of turf health values was variable by month in each green, and no spatial relationship was determined between turf health values and fungal presence. Five ERI fungal isolates were exposed to four fungicide classes with relative growth present at 100 ppm. The EC50 values for the selected fungi ranged from 2.33 to >100 ppm and suggests a lack of sensitivity to the selected fungicides.

Warm-season turf species are becoming increasingly popular for putting green use in the transition zone. Ultradwarf bermudagrass (Cynodon dactylon (L.)  C. transvaalensis Burtt-Davy) is the prevalent warm-season putting green species, but seashore paspalum (Paspalum vaginatum Swartz) and ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] may also be grown in the transition zone. Warm-season species are susceptible to winter injury and may require different management regimes than cool-season species. Therefore, the objectives of this research were to assess the impacts of various management practices on warm-season putting green species and characterize the physiological basis for differences in freeze tolerance of various warm-season putting green species. Field studies determined sampling procedures form thatch-mat depth and soil organic matter content of warm-season putting greens and assessed the impact of various management practices on different warm-season putting green species/varieties. The relative freeze tolerance of ‘Champion’ and ‘TifEagle’ ultradwarf bermudagrass cultivars, ‘SeaDwarf’ seashore paspalum, and Diamond zoysiagrass were determined, along with the accumulation of proline and polyamines during cold acclimation, in growth chamber studies. All species/varieties required different sampling numbers for determination of thatch-mat depth and soil organic matter. More sand was incorporated into the turf canopy and surface hardness was increased with brushing and vibratory rolling TifEagle putting greens after sand topdressing application than either treatment alone. Putting green management programs with lower mowing heights and increased mowing frequencies increased ball roll distance on a MiniVerde putting green without negatively affecting turf quality. Weekly vertical mowing + daily grooming on TifEagle reduced thatch depth and turfgrass quality, while increasing topdressing incorporation over either treatment alone. Diamond was the most freeze tolerant species/variety, followed by TifEagle, Champion, then SeaDwarf. Cold acclimation increased proline concentration for all species/varieties except SeaDwarf, but had inconsistent effects on polyamines. Spermidine and putrescine concentrations differed with species/variety, but were not correlated to freeze tolerance.

Traditional aerification programs can cause substantial damage to the playing surface resulting in prolonged recovery. A growing trend in the industry involves using aerification techniques that cause minimum surface disruption; however, despite growing interest in new and alternative aerification technology, there is a lack of information in the literature comparing new or alternative technology with traditional methods on warm season grasses. Therefore, the objective of this research was to determine the best combination of new dry-injection (DI) cultivation technology with modified traditional aerification programs to achieve minimal surface disruption without a compromise in soil physical properties. Research was conducted at the Mississippi State University golf course practice putting green and at the Mississippi State University practice football field during. Treatments compared different combinations of hollow tine (HT) aerification and DI from Jun to Aug in 2014 and 2015.

This research addressed the effects of cultural management practices, cultivar selection, and applications of seasonal fungicides on ultradwarf bermudagrass health and playability and occurrence of foliar diseases. Additionally, novel ectotrophic root-infecting fungi were isolated from ultradwarf bermudagrass roots exhibiting symptoms of summer decline, identified via multilocus phylogenetic analyses, and characterized by morphological assessments and pathogenicity evaluations.

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. / Doctor of Philosophy / Ultradwarf bermudagrass putting greens are commonly found on golf courses in warm climates. These grasses thrive in heat and humidity but are susceptible to injury or death when exposed to cold temperatures. This research is focused on evaluating management practices that may impact bermudagrass' susceptibility to injury from cold temperature exposure. The cultural practices evaluated include turf covers, fungicide programming, core aeration, and the use of plant growth regulators to manipulate the turfgrasses own self defense mechanisms. Our results show that the use of turf covers significantly increased putting green 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 commonly-used fungicides improved putting green quality throughout winter dormancy and spring green up. The addition of a green-pigmented phosphonate fungicide significantly improved winter and spring putting green quality. The addition of a plant defense activator, acibenzolar-S-methyl to fungicide programs did not improve winter 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 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 soil moisture content of the putting greens were impacted by construction method but were not significantly impacted by core aeration programs. Field research revealed that 'fall only' and 'fall and winter' plant growth regulator applications improved ultradwarf bermudagrass quality but only 'fall and winter' delayed premature green-up in early spring when the turfgrass can be susceptible to low temperature injury. Growth chamber studies revealed that plants treated with the growth regulator, trinexapac-ethyl were more sensitive to low-temperature exposure than non-treated plants. Together, these results increase our understanding of the impact of management practices on UDB winter quality, CD, and low temperature injury.