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Current recommended nitrogen fertilization rates for St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] in South Florida range from 4 to 6 lb N per 1,000 ft2 per yr, applied throughout the year. Nevertheless, strict fertilizer ordinances are being passed by multiple counties in Florida, setting limits to the amount of N that can be applied to turfgrass areas, and establishing summer blackout periods for fertilizer applications; hence, there is a need to identify the minimum N rates to sustain St. Augustinegrass quality. A 4‐yr study was conducted at the University of Florida's Fort Lauderdale Research and Education Center to assess the turfgrass quality of four St. Augustinegrass cultivars ('CitraBlue', 'Floratam', 'Palmetto', and 'Raleigh') grown on a Hallandale fine sand (siliceous, isohyperthermic Lithic Psammaquents) and fertilized at either 2.5 or 5 lb per 1,000 ft2 per yr. Plots were evaluated monthly for visual turfgrass quality, and yearly for genetic color, leaf texture, spring green‐up, and summer density. CitraBlue had the highest turfgrass quality, color, and density. Differences were rarely detected among the other three cultivars. Nitrogen rates had an effect only on summer density, suggesting that St. Augustinegrass grown on Hallandale fine sand with 3.4% organic matter in South Florida could be managed with less N than is currently recommended without detrimental effects. Core Ideas: Over a 4‐yr period, 2.5 lb N per 1,000 ft2 per yr yielded adequate St. Augustinegrass quality.CitraBlue outperformed older cultivars in the trial.Minimal differences were detected among Floratam, Palmetto, and Raleigh.When soil organic matter is considerable, low N rates may provide sufficient lawn quality. [ABSTRACT FROM AUTHOR]

Understanding rooting dynamics using the minirhizotron technique is useful for cultivar selection and to quantify nematode damage to roots. A 2-yr microplot study including five bermudagrass ('Tifway', Belonolaimus longicaudatus susceptible; two commercial cultivars [TifSport and Celebration] and two genotypes ['BA132' and 'PI 291590'], which have been reported to be tolerant to B. longicaudatus) and two St. Augustinegrass ('FX 313', susceptible, and 'Floratam' that was reported as tolerant to B. longicaudatus) genotypes in a 5 x 2 and 2 x 2 factorial design with four replications, respectively, was initiated in 2012. Two treatments included were uninoculated and B. longicaudatus inoculated. In situ root images were captured each month using a minirhizotron camera system from April to September of 2013 and 2014. Mixed models analysis and comparison of least squares means indicated significant differences in root parameters studied across the genotypes and soil depths of both grass species. 'Celebration', 'TifSport' and 'PI 291590' bermudagrass, and 'Floratam' St. Augustinegrass had significantly different root parameters compared to the corresponding susceptible genotypes (P ≤ 0.05). Only 'TifSport' had no significant root loss when infested with B. longicaudatus compared to non-infested. 'Celebration' and 'PI 291590' had significant root loss but retained significantly greater root densities than ' Tifway' in B. longicaudatus-infested conditions (P ≤ 0.05). Root lengths were greater at the 0 to 5 cm depth followed by 5 to 10 and 10 to 15 cm of vertical soil depth for both grass species (P≤ 0.05). 'Celebration', 'TifSport', and 'PI 291590' had better root vigor against B. longicaudatus compared to Tifway. [ABSTRACT FROM AUTHOR]

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a warm season turfgrass and is widely used for lawns and landscapes in the southern United States of America. The southern chinch bug (Blissusinsularis Barber) is the most damaging insect of St. Augustinegrass. Use of resistant cultivars is an environmentally sound and sustainable method to control this insect pest. Two newly identified resistant St. Augustinegrass lines (NUF3231 and NUF4872) were compared with three commercial cultivars for turfgrass quality and other important traits. The two lines had turf color and turf visual quality similar to those of Captiva and similar to or better than those of Floratam and Palmetto during the experiment. NUF4872 had higher level of resistance to gray leaf spot than Floratam and Palmetto. Stolon architectures of NUF3231 were similar to those of Captiva whereas NUF4872 had the stolons similar to those of Floratam. The results indicated that the two lines could potentially be released as commercial cultivars for use on lawns to battle against the southern chinch bug. [ABSTRACT FROM PUBLISHER]

As a result of increasing demand for potable water, local and national initiatives to conserve municipal water supplies have been implemented. Many of these initiatives focus on reducing irrigation of turfgrass in urban landscapes and may totally ban irrigation during periods of severe water shortage. Proper selection of adapted turfgrass species and cultivars is vital to long-term water conservation initiatives. Turfgrasses that can survive and recover from extended hot and dry periods under limited to no irrigation would best meet water conservation objectives. The present study was conducted to evaluate the recuperative potential of transplanted plugs of 24 commonly grown cultivars of three warm-season turfgrass species after incremental increases in water stress imposed by withholding all water for up to 60 days. A 2-year field study was conducted consisting of eight blocks containing 25 plots each. Each block was planted with one plot each of eight cultivars of bermudagrass (Cynodon dactylon sp.), seven cultivars of st. augustinegrass (Stenotaphrum secundatum sp.), and nine cultivars of zoysiagrass (five of Zoysia japonica sp. and four of Zoysia matrella sp.). Four blocks were planted on native soil with no restriction to rooting, whereas the other four had an effective root zone of only 10 cm of soil. Cup cutter plugs were collected at predetermined intervals, transported to College Station, TX, replanted, and grown under well-watered conditions. Measurements of the lateral spread of the plugs were taken every 10 to 14 days for the first 60 to 70 days after planting (DAP). The lateral spread of plugs collected after 0 days of summer dry-down (DSD) was greatest for bermudagrass, intermediate for St. augustinegrass, and lowest for zoysiagrass. In most cases there were no consistent differences between cultivars within a species. All species grown on the 10-cm deep root zone were unable to survive the 60-day period without water and died within the first 40 days. For each species, lateral spread was increasingly delayed or reduced with increasing DSD. Although all three species grown on native soil were able to survive and recover from a 60-day period without water, the bermudagrass cultivars had the most rapid recovery rates measured as lateral spread of transplanted plugs. [ABSTRACT FROM AUTHOR]

Hybridization and selection has been one of the methods used to generate turfgrass cultivars in buffalograss improvement. Three half-sib populations were developed by crossing three buffalograss female genotypes, NE 3296, NE 2768, and NE 2769, with NE 2871, a male genotype, to 1) investigate the pattern of genetic variability generated for turfgrass characteristics through hybridization; 2) assess the effect of parental change on the level of genetic variability generated in a buffalograss diploid population; and 3) predict the performance of a progeny generated from two heterozygous parents for turfgrass performance. The four parents and 20 random F1 progeny selected from each population were established in 2006 at the John Seaton Anderson Turfgrass Research Facility located near Mead, NE. A randomized complete block design (RCBD) was used with the progeny nested in the crosses. A visual rating scale of 1-9 was used to evaluate the population. Mean population lateral spread, genetic color, density, and turfgrass quality from early summer to fall ranged from 3.5 to 4.5, 7.1 to 7.9, 6.9 to 8.1, and 5.2 and 6.8, respectively. There were significant differences among the crosses and the parents for all the traits studied except quality in June and August. The progeny nested within crosses differed for turfgrass genetic color and quality. Best linear unbiased prediction (BLUP) indicated a high improvement potential for turfgrass lateral spread and spring density in NE 2768 x NE 2871 and for turfgrass genetic color in NE 3296 x NE 2871. From these findings, it can be concluded that hybridization breeding is a worthwhile approach for generating and identifying transgressive segregants fiw specific buffalograss traits. [ABSTRACT FROM AUTHOR]

Drought responsive turfgrass cultivars are becoming increasingly important in water conservation. Eight cultivars of bermudagrass [Cynodon dactylon (L.) Pers.], one cultivar of buffalo grass [Buchioe dactyloides (Nutt.) Engelm.], and two root-zone depths were evaluated for drought response and recovery during consecutive 60-d drought and 60-d recovery periods over 2 yr. Individual cultivar responses to drought and post-drought recovery time were quantified through digital image analysis as the number of days to decrease to or increase to 50% green ground cover, respectively. No grass survived the 60-d drought when planted on the restricted 10-cm soil depth in 2006 or 2007, while all entries survived when planted on the unrestricted native soil depth. Both study years provided unique conditions for investigating drought response as the mean time to reach 50% green ground cover differed by 17 d between the 2 yr of study. Some cultivars lost 50% green ground cover in 20 d while other cultivars lasted the entire 60-d drought period without losing 50% green ground cover. Post-drought turfgrass recovery responses differed by as much as 45 d in achieving 50% green ground cover. Documenting individual cultivar responses to drought and recovery may provide perspective on individual grass cultivars that may initiate poor irrigation management behavior due to early leaf firing as well as refine consumer expectations following drought conditions. [ABSTRACT FROM AUTHOR]

As water resources become restricted for use on amenity turfgrass systems, the inability for consumers to delineate incremental drought stress relating to plant health can result in the misuse of water resources during drought conditions. Seven cultivars of St. Augustinegrass (SA) [Stenotaphrum secundatum (Walt.) Kuntze] and two root zone depths were evaluated for drought response and recovery during consecutive 60-d drought and 60-d recovery periods over 2 yr. Using digital image analysis, drought response and recovery were quantified as the number of days to decrease or increase to 50% green ground cover, respectively. Both study years provided unique conditions for investigating drought response as the mean time to reach 50% green ground cover differed by 24 d between the 2 yr of study. Some SA cultivars lost 50% green ground cover in 23 d while other cultivars lasted the entire 60 d drought period without losing 50% green ground cover. Floratam provided the most consistent drought response and recovery compared to other SA cultivars. Once water was no longer limited, cultivars demonstrated up to a 52 d difference in attaining 50% green ground cover. Results could significantly impact home consumer irrigation behaviors and influence consumer expectations of turfgrass following drought conditions. [ABSTRACT FROM AUTHOR]

The Rhodesgrass mealybug (Antonina graminis) (Hemiptera: Pseudococcidae), is resurging as an important pest of turfgrass across Texas and the Southeastern United States. This mealybug is known to feed on many warmseason turfgrasses and pasturegrasses. Twenty-seven cultivars from nine genera of turfgrass were evaluated for susceptibility and preference by the mealybug. Cultivars of kikuyugrass (Pennisetum clandestinum Hochst) and bermudagrass (Cynodon spp.) were significantly more susceptible than cultivars of seven other genera of turfgrass. Cultivars of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], buffalograss [Buchloe dactyloides (Nutt.) Engelm], and zoysiagrass (Zoysia spp.), each exhibited susceptibility of >2 mealybugs per 7.5 x 7.5-cm plant. Populations did not exceed ≤0.5 mealybug per plant on centipedegrass [Eremochloa ophiuroides (Munro) Hack.], seashore paspalum (Paspalum vaginatum Swartz), bahiagrass (Paspalum notatum Flugge), or tall fescue (Festuca arundinacea Schreb). [ABSTRACT FROM AUTHOR]

ABSTRACT Southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae),is the most serious insect pest of St. Augustinegrass Stenotaphruni secundatum (Walter) Kuntze, a common lawngrass grown in southeastern U.S. states. Host plant resistance to southern chinch bug has been identified in the polyploid St. Augustinegrass'FX-10' and the diploid `Captiva'. The objective of this research was to identify possible physical mechanism(s) explaining chinch bug resistance in these cultivars. We studied the distribution of chinch bug salivary sheaths in the preferred tissue for feeding (the axillary shoot) of the two resistant cultivars and two susceptible cultivars, paired for ploidy (`Floratam', polyploid, and Palmetto, diploid). We also investigated the potential role of axillary shoot lignification and anatomy in chinch bug resistance. Salivary sheaths were more abundant on the outermost leaf sheath of axillary shoots of resistant cultivars compared with susceptible cultivars. In contrast, fewer salivary sheaths reached the innermost meristematic tissue in the axillary shoots of resistant St. Augustinegrass cultivars than in the two susceptible cultivars. The polyploid cultivars FX-1O and Floratam had higher total lignin in axillary shoots compared with the diploid cultivars Captiva and Palmetto. However, total lignin content was not correlated with resistance to southern chinch bug. Light microscopic studies found no differences in epidermal layer thickness among resistant and susceptible St. Augustinegrass cultivars. However, transmission electron microscopic studies revealed that the cell walls of the sclerenchyma cells around the vascular bundle of southern chinch bugresistant FX-10 and Captiva were significantly thicker than the cell walls in susceptible Floratam and Palmetto. Our research suggests that the thick-walled scierenchyma cells around the vascular bundle play a role in southern chinch bug resistance in St. Augustinegra.ss, possibly by reducing stylet penetration to the vascular tissue. [ABSTRACT FROM AUTHOR]

Buffalograss [Buchloë dactyloides (Nutt.) Engelm.] is a turfgrass species with reduced irrigation and fertilization requirements, relative to traditional turfgrasses. Interest in reducing the amount of chemicals and water applied to turfgrass has resulted in increased efforts to improve buffalograss as a turfgrass. As interest in using the new turf-type buffalograss cultivars has increased, the need for nitrogen rate and mowing height recommendations supported by research have become necessary. 'Cody', 'Texoka', '378', and 'NE 91-118' buffalograss cultivars were planted at sites located in Nebraska, Kansas, and Utah to determine nitrogen rate and mowing height effects on buffalograss quality, color, density, and clipping yield. There were significant cultivar × nitrogen rate interactions at all sites for quality, color, and density. Regardless of cultivar, nitrogen rate × year interactions at all sites revealed that the 98 kg N ha-1 rate sustained quality, color, and density over the 3-yr evaluation period, while lower nitrogen rates had decreased quality, color, and density. The 195 kg N ha-1 rate improved quality over the 3-yr period but also had the highest clipping yields. Regardless of the cultivar selected, the data support the general mowing height recommendation for turf-type buffalograss of 5.0 to 7.5 cm. For golf course fairways maintained at a mowing height of 2.5 cm, the vegetatively established cultivars (NE 91-118 and 378) are the best choice to achieve high turfgrass quality. [ABSTRACT FROM AUTHOR]

Buffalograss [Buchloe dactyloides (Nutt.) Englem] germplasm has a broad resource of genetic diversity that can be used for turfgrass, forage and conservation. Buffalograss is the only native grass that is presently used as a turfgrass in the Great Plains region of North America. Its low growth habit, drought tolerance and reduced requirement for fertilizer and pesticides contribute to interest in its use. The objectives of this study were to use sequence-related amplified polymorphism (SRAP) markers in the evaluation of genetic diversity and phenetic relationships in a diverse collection of 53 buffalograss germplasms, and to identify buffalograss ploidy levels using flow cytometry. Based on their DNA contents, buffalograss genotypes were grouped into four sets, corresponding to their ploidy levels. Thirty-four SRAP primer combinations were used. This is the first report of the detection of differentiating diploid, tetraploid, pentaploid and hexaploid buffalograss genotypes, representing diverse locations of origin, using SRAP markers. Cluster analysis by the unweighted pair-group method with arithmetic averages based on genetic similarity matrices indicated that there were eight clusters. The coefficients of genetic distance among the genotypes ranged from 0.33 up to 0.99 and averaged D=0.66. The genetic diversity estimate, He, averaged 0.35. These results demonstrated that genotypes with potential traits for turfgrass improvement could readily be distinguished, based on SRAP. The use of PCR-based technologies such as SRAP is an effective tool for estimating genetic diversity, identifying unique genotypes as new sources of alleles for enhancing turf characteristics, and for analyzing the evolutionary and historical development of cultivars at the genomic level in a buffalograss breeding program. [ABSTRACT FROM AUTHOR]

The chinch bug, Blissus occiduus Barber, has been documented as a serious pest of buffalograss, Buchloë dactyloides (Nutall) Engelmann, and zoysiagrass, Zoysia japonica Steudel, turf grown in the Midwest. in addition to these two warm-season turfgrasses, several other warm-season grasses, including bermudagrass, Cynodon dactylon (L.) Pers., may also be at risk of B. occiduus infestations. This research evaluated selected bermudagrass and zoysiagrass cultivars for resistance to B. occiduus. Eleven zoysiagrass and four bermudagrass cultivars were evaluated for resistance to B. occiduus using no-choice studies under greenhouse conditions. Based on turfgrass damage ratings, the zoysiagrasses 'Diamond', 'Zoro', and 'Emerald', and bermudagrass 'Mini Verde' were identified as moderately resistant to B. occiduus. The zoysiagrasses 'Zenith', 'Meyer', and 'Crowne', and bermudagrasses 'Tifway 419' and 'Tifsport" were characterized as highly to moderately susceptible to B. occiduus. These results provide the first report of resistance to B. occiduus in zoysiagrass and bermudagrass germplasm. [ABSTRACT FROM AUTHOR]