Turfgrass Cultivars Research Articles

Assessing drought resistance in seashore paspalum genotypes using leaf gas exchange, osmotic adjustment, and rooting characteristics

AbstractThe objective of this study was to compare drought resistance in a range of seashore paspalum (Paspalum vaginatum Sw.) genotypes and identify associated morphological and physiological traits. Fifteen genotypes were grown in growth chamber conditions and exposed to well‐watered and drought‐stress treatments. Genotypes ‘Seaisle1’ and PI647891 were consistent top performers, whereas ‘Seastar’ and PI614680 performed poorly as measured by turf quality, percentage green cover, and relative water content when exposed to drought stress. Observed levels of drought resistance had no significant relation with morphological traits such as leaf width and internode length but were found to be associated with various physiological traits. Drought resistant genotypes were able to better maintain membrane stability, photosynthesis, and had greater water use efficiency compared with sensitive genotypes. Earlier osmotic adjustment at 7 d via faster osmolyte accumulation was a significant contributor to performance during drought. Drought‐resistant Seaisle1 and PI647891 had deeper roots and greater root length density than drought sensitive ‘Seastar’ and PI614680. Results showing variability in the level of drought resistance and associated mechanisms in understudied seashore paspalum genotypes could facilitate future breeding efforts for developing drought‐resistant turfgrass cultivars.

Sod production characteristics: How strong is your bermudagrass?

AbstractFor new, vegetatively propagated turfgrass cultivars to be successful in the marketplace, they must not only possess characteristics desired by the end user, but also have those preferred by the sod producer. The objectives of this study were (1) to investigate different sod production characteristics of advanced clonal bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] lines that show improved characteristics and (2) to examine the relationship between those production characteristics. Production characteristics measured include: sod handling quality (SHQ), sod tensile strength (STS), vertical growth (VG), and underground growth characteristics. Results showed a positive correlation (r2 = 0.65) between SHQ and STS. Other production characteristics moderately correlated or did not correlate at all. Knowledge of growth characteristics can aid breeders in choosing breeding lines that will add value to the sod industry.

Relative Traffic Tolerance of Warm-Season Grasses and Suitability for Grazing by Equine

Warm season wear-tolerant turfgrasses, such as those used on golf courses and athletic fields, may be valuable forages on equine operations because of their potential to remain viable during heavy hoof traffic. Crabgrass may also be suitable as it thrives in conditions where other grasses have limited success. The objective of this study was to assess the relative traffic tolerance and nutritional composition of five warm-season (WS) turfgrass cultivars of bermudagrass and zoysiagrass and one WS forage-type crabgrass. All cultivars were established by seed in replicated monoculture plots. Simulated hoof traffic treatments consisted of either none, one, or two passes of a Baldree Traffic Simulator. Traffic was applied weekly for 6 weeks in the summer of 2016 and 2017, with each treatment period followed by a 4-week rest period. Plots were assessed for compaction, biomass, and persistence before and after treatment and rest periods. Nutritional composition was assessed throughout the growing seasons. Soil compaction increased as treatment level increased for all cultivars (P < .0001). There was no effect of treatment on cultivar persistence. Biomass available for grazing was increased in year 1 by the application of LOW traffic treatment (P = .0193). Both bermudagrass and zoysiagrass cultivars showed promise for use in areas of heavy traffic on equine operations, however, zoysiagrass cultivars were more suitable as they were highest ranking in relative traffic tolerance, moderate in yield, and low nonstructural carbohydrates (<12% NSC). Future on-farm studies evaluating bermudagrass and zoysiagrass to determine ideal stocking rate, management methods, and persistence under grazing are warranted.

Adaptation and Some Quality Parameters of Cool Season Turfgrass Species in Samsun Conditions

The aim of this study is to determine adaptation and quality parameters of some cool season turfgrass cultivars and species, In the scope of this study, leaf form, variation of leaf colour according to the seasons, tiller number, thinning ratio, weed ratio and general appearance of the species were determined. The experiment was established according to confounding design with four replications in Samsun Conditions at November, 2010. According to 1000 seed weight and characteristics of the plants seeding ratios were determined as pure and viable seed as follows; Lolium perenne 40 g m-2, Festuca rubra var. rubra and Festuca rubra var. commutata 30 g m-2, Festuca arundinacea 40 g m-2, Poa pratensis 20 g m-2, Festuca rubra trichophylla 30 g m-2, Agrostis stolonifera and Agrostis tenuis 5 g m-2, Festuca ovina 25 g m-2. According to the results obtained from this study it was determined that species/cultivars have some superiority to each other because of their different morphological and physiological characteristics. When we consider weed competition, Lolium perenne and Festuca arundinaceae cultivars have to be added to the mixture in order to decrease weed competition. There was colour variation distinctively depending on the seasons for all species. But, compare to the others, cultivars of Agrostis sp. and Poa pratensis cultivars have the potential to keep leaf colour in different seasons. Leaf form and appearance of Festuca rubra, Poa trivialis and Festuca ovina are better than the others. In order to keep good conditions of turfgrass areas, especially after cutting in summer period, Poa pratensis and Poa trivialis should added in mixtures to get benefit their higher regenerating power.

Daily light integral requirements of warm‐season turfgrasses for golf course fairways and investigating in situ evaluation methodology

AbstractDetermining daily light integral (DLI) requirements for turfgrass systems has been an effective method to quantify photosynthetically active radiation (PAR) necessary to maintain quality turfgrass in a research setting. However, there has been little research estimating DLI requirements of popular turfgrass cultivars of zoysiagrass [Zoysia matrella(L.) Merr. andZ. japonicaSteud.], hybrid bermudagrass [Cynodon dactylon(L.) Pers. ×C. transvaalensisBurtt Davy], and common bermudagrass [C. dactylon(L.) Pers.] used for teeing grounds and fairways on golf courses. The objective of this research was to (a) determine minimum DLI requirements of two zoysiagrasses, ‘Cavalier’ (Z. japonica) and ‘Meyer’ (Z. matrella), and two bermudagrasses, common bermudagrass (cultivar unknown) and ‘Astro‐DLM’ hybrid bermudagrass; and (b) investigate methodology in rapidly estimating DLI requirements in situ at area golf courses for the same cultivars. Cultivars were evaluated under 22, 40, 60, and 90% shade in a field research setting over two seasons from August through October 2016 and May through October 2017. Turfgrass quality continued to decline over the 2‐yr trial, emphasizing importance of multi‐year evaluations encompassing cumulative effects of shade on turfgrass. Estimated minimum DLI requirements for turf quality of Astro‐DLM hybrid bermudagrass, common bermudagrass, Cavalier zoysiagrass, and Meyer zoysiagrass were 20.4, 25.9, 15.0, and 21.1 mol m−2d−1, respectively. In situ evaluations at golf course sites accurately estimated DLI requirements for three of four cultivars in comparison to those obtained in field research setting. Established minimum DLI requirements determined for cultivars in this study provide a baseline for site specific turfgrass selection.

User Preferences for Accessing Publically Available Turfgrass Cultivar Performance Data

Identifying sources of turfgrass cultivar performance data can be difficult for many consumers. Currently, the best source for data of this type is the National Turfgrass Evaluation Program (NTEP). Unfortunately, these data are made public in a format that is not readily usable for most consumers. Ideally, turfgrass cultivar data would be available in an easily accessible database. We conducted an online survey to investigate user preferences for accessing publically available turfgrass performance data in the United States. We found users desire a turfgrass cultivar performance database that allows for the identification of cultivars best adapted and tolerant to environmental stresses. The information on turfgrass mixtures and blends is also important to most users. Users’ sociodemographic backgrounds, such as gender, education, occupation, and experience in the turf industry, affected their attitudes toward information provided in the turfgrass database. Turfgrass consumers need the new database to provide information on identifying turfgrass options that are resource efficient and endophyte resistant. Turfgrass breeders, researchers, and extension specialists use the turfgrass database to compare different turfgrasses cultivars to do further analysis. The results of this study provide important implications on how an updated turfgrass cultivar performance database and platform can fulfill the different needs of turfgrass researchers, extension personnel, breeders, and stakeholders.

Salinity Tolerance and Recovery Attributes of Warm-season Turfgrass Cultivars

As population growth places greater pressures on potable water supplies, nonpotable recycled irrigation water is becoming widely used on turfgrass areas including golf courses, sports fields, parks, and lawns. Nonpotable recycled waters often have elevated salinity levels, and therefore turfgrasses must, increasingly, have good salinity tolerance to persist in these environments. This greenhouse study evaluated 10 commonly used cultivars representing warm-season turfgrass species of bermudagrass (Cynodon spp.), zoysiagrass (Zoysia spp.), st. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and seashore paspalum (Paspalum vaginatum Swartz) for their comparative salinity tolerance at electrical conductivity (EC) levels of 2.5 (control), 15, 30, and 45 dS·m–1. Salinity treatments were imposed on the grasses for 10 weeks via subirrigation, followed by a 4-week freshwater recovery period. Attributes, including turf quality, the normalized difference vegetation index (NDVI), canopy firing, and shoot biomass reductions were evaluated before and after salinity stress, as well as after the 4-week freshwater recovery period. Results showed considerable differences in salinity tolerance among the cultivars and species used, with the greatest tolerance to elevated salinity noted within seashore paspalum cultivars and Celebration® bermudagrass. In comparison with growth in 2.5-dS·m–1 control conditions, increased shoot growth and turf quality were noted for many bermudagrass and seashore paspalum cultivars at 15 dS·m–1. However, st. augustinegrass and some zoysiagrass cultivars responded to elevated salinity with decreased growth and turf quality. No cultivars that had been exposed to 30- or 45-dS·m–1 salinity recovered to acceptable levels, although bermudagrass and seashore paspalum recovered to acceptable levels after exposure to 15-dS·m–1 salinity. More severe salinity stress was noted during year 2, which coincided with greater greenhouse temperatures relative to year 1.

Turfgrass Cultivar Diversity Provides Associational Resistance in the Absence of Pest Resistant Cultivars.

Turfgrasses are ubiquitous in urban landscapes and can provide numerous ecosystem services. However, most warm season turfgrasses are produced, planted, and maintained as cultivar monocultures, which may predispose them to herbivore attack and reduce the services lawns provide. Though rarely done, host plant resistance can be used as a strategy to reduce herbivory and preserve beneficial services. Increasing turfgrass cultivar diversity may provide similar or greater benefits through associational resistance, whereas conserving desirable maintenance and aesthetic traits. However, no studies have examined this in warm season turfgrasses. To address this, we evaluated host plant resistance to fall armyworm (Spodoptera frugiperda [J.E. Smith] [Lepidoptera: Noctuidae]) in commercially available cultivars of St. Augustinegrass (Stenotaphrum secundatum [(Walt.) Kuntz] [Lepidoptera: Noctuidae]) and then investigated if the resistance or susceptibility of St. secundatum cultivars carried over in mixed cultivar plantings. Through a no-choice experiment and a limited-choice experiment, we detected no host plant resistance in monocultures of St. secundatum cultivars. However, we did find that as cultivar diversity increased, female Sp. frugiperda larval weight and herbivory decreased. Additionally, choice tests indicated that larvae prefer less diverse stands of St. secundatum cultivars. Interestingly, our results suggest that in the absence of host plant resistance, warm season turfgrass cultivar diversity may reduce herbivore pest fitness and damage. These results demonstrate that warm season turfgrass cultivar diversity may be a viable integrated pest management tool that warrants further investigation.

Heterogeneity in urban consumer preferences for turfgrass attributes

Managing lawns in urban landscapes has become a contentious issue in public policy due to conflicts over water consumption and the potential for runoff of fertilizer, pesticides, and herbicides into water bodies. Maintaining an attractive residential lawn entails choosing a turfgrass variety that can minimize challenges associated with water requirements, salinity, shade, winter stress, and high maintenance costs. Turf producers and breeders attempt to produce new and improved turf cultivars, but they are largely unaware of the consumers’ preferences for specific turfgrass attributes. This study illustrates the use of discrete-choice analysis, a stated preference marketing valuation technique in estimating consumers’ preferences and willingness to pay for turfgrass attributes. Results of a survey of 1,179 household consumers indicate that preferences for stress tolerant turfgrass cultivars are highly heterogeneous. A latent class model shows that household turf consumers are clustered in two broad classes; “Willing Hobby Gardeners” and “Reluctant Mature Homeowners”. Willing hobby gardeners are characterized as hobbyists and more willing adopters of improved turfgrass cultivars, while reluctant mature homeowners are characterized by mature (more than 45 years of age) homeowners and more reluctant adopters of improved turfgrass cultivars that minimize environmental stressors. Results show that Willing Hobby Gardeners are most likely to pay more for improved turfgrass attributes than Reluctant Mature Homeowners. This categorization of consumers may help sod producers, urban planners, and landscape firms in targeting willing gardeners and in strategizing how to reach reluctant homeowners.

The Salinity Tolerance of Seeded-type Common Bermudagrass Cultivars and Experimental Selections

Turfgrass managers are using reclaimed water as an irrigation resource because of the decreasing availability and increasing cost of fresh water. Much attention, thereby, has been drawn to select salinity-tolerant turfgrass cultivars. An experiment was conducted to evaluate the relative salinity tolerance of 10 common bermudagrasses (Cynodon dactylon) under a controlled environment in a randomized complete block design with six replications. ‘SeaStar’ seashore paspalum (Paspalum vaginatum) was included in this study as a salinity-tolerant standard. All entries were tested under four salinity levels (1.5, 15, 30, and 45 dS·m−1) consecutively using subirrigation systems. The relative salinity tolerance among entries was determined by various parameters, including the normalized difference vegetation index (NDVI), percentage green cover determined by digital image analysis (DIA), leaf firing (LF), turf quality (TQ), shoot vertical growth (VG), and dark green color index (DGCI). Results indicated that salinity tolerance varied among entries. Except LF, all parameters decreased as the salinity levels of the irrigation water increased. ‘Princess 77’ and ‘Yukon’ provided the highest level of performance among the common bermudagrass entries at the 30 dS·m−1 salinity level. At 45 dS·m−1, the percent green cover as measured using DIA varied from 4.97% to 16.11% among common bermudagrasses, where ‘SeaStar’ with a DIA of 22.92% was higher than all the common bermudagrass entries. The parameters LF, TQ, NDVI, DGCI, VG, and DIA were all correlated with one another. Leaf firing had the highest correlation with other parameters, which defined its value as a relative salinity tolerance measurement for common bermudagrass development and selection.

Heritability of Simulated Wear and Traffic Tolerance in Three Fine Fescue Species

In recent years, turfgrass breeders have given increased attention to the development of lower maintenance turfgrass cultivars. Fine fescues (Festuca spp.) have been identified as potential candidate species for low-maintenance lawns because of their reduced need for water, mowing, and fertilizer. Unfortunately, these species have some weaknesses that must be improved to facilitate their use; perhaps, the most important of these is tolerance to wear and traffic. For this trait to be improved in new cultivars, there must be sufficient heritable variation available for plant breeders to exploit; however, little is known about the heritability of this complex trait in fine fescue species. Therefore, the objective of this study was to determine the heritability of wear and traffic tolerance in three fine fescue species. Replicated field studies were established in North Brunswick, NJ, and St. Paul, MN, and each included 157 Chewing’s fescue (Festuca rubra L. subsp. fallax), 155 hard fescue (Festuca brevipilia), and 149 strong creeping red fescue (F. rubra L. subsp. rubra) genotypes. Wear tolerance was evaluated in North Brunswick and traffic tolerance was evaluated in St. Paul during 2015 and 2016 using different simulators to determine both plant performance and broad-sense heritability estimates for wear and traffic tolerance. Broad-sense heritability estimates for the three species when calculated on a clonal basis was between 0.69 and 0.82 for wear tolerance in the North Brunswick location and between 0.49 and 0.60 for traffic tolerance in the St. Paul location. On a single-plant basis, broad-sense heritability estimates for the three species were between 0.31 and 0.45 for wear tolerance in the North Brunswick location and 0.09 and 0.12 for traffic tolerance in St. Paul. However, this research does indicate that improvement of wear and traffic tolerance in fine fescues is possible through recurrent breeding methods based on selection of replicated clonally propagated genotypes rather than selection of single individual plants of a population. This was the first study to determine the genetic effects of wear and traffic tolerance in any turfgrass species.

Evaluation of bermuda and paspalum grass types for urban landscapes under saline water irrigation

ABSTRACTIn the arid regions, turfgrass cover is an integral part of landscape to protect the soil from erosion, enhance the aesthetic value, and improve the microclimate. The salinity and the scarcity of fresh water of the arid region are the major challenging factors in turfgrass production. Therefore, the need for salt tolerant turfgrass with functional quality is necessary to improve the turf performance. The detrimental effects of salinity include growth suppression, and lowered osmotic potential ultimately leading to firing of the leaf blades. In this context, the study was undertaken to determine the relative salt tolerance and growth response of turfgrass genotypes in order to recommend turfgrass cultivars that can tolerate high salinity irrigation and maintain excellent visual and functional qualities under United Arab Emirates (UAE) condition. The paspalum cultivars maintained the highest succulence percentage compared to the bermudagrass cultivars under enhanced salinity levels. The shoots count, fresh weight (FW), and dry weight (DW) were found highest in paspalum types. The chlorophyll a, chlorophyll b and the total chlorophyll content was found higher in bermuda grass types under high salinity levels. The bermudagrass cultivars showed significantly higher carotenoids, anthocyanins and proline compared to the paspalum types under salt stress condition. In the case of princess 77 and Yukon, an inherently high amount of proline was recorded which confirmed an increase up to 10,000 ppm and drastically declined beyond this concentration. Sea Dwarf paspalum and Sea Isle 2000 maintained uniformity in the proline level at all levels of salinity without significant variation. These findings point to the fact that both paspalum and bermuda types exhibited varied responses to different physiological and biochemical parameters under the saline conditions. Paspalum types have an edge over the bermudagrass in terms of shoot density, which is a potential factor in determining the high-quality turfs. Bermudagrass types can be applied in lower salinity conditions based on the responses as evidenced from the present results.

Low-maintenance turfgrass potential of crested, thickspike and western wheatgrass germplasm

Traditional cool-season turfgrass species, such as Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Lolium arundinaceum [Schreb.] Darbysh.), provide high quality turfgrass for athletic and aesthetic uses. Unfortunately, this high level of quality often comes at a cost of high levels of inputs in the forms of irrigation and fertilization. Therefore, there is a growing need and demand to produce turfgrass with lower inputs, particularly irrigation. Herein, we describe a study of the turfgrass potential of crested wheatgrass (Agropyron cristatum [L.] Gaertn.), thickspike wheatgrass (Elymus lanceolatus [Scribn. & J.G. Sm.] Gould) and western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) when managed under low irrigation. We found that these species generally exhibited lower percent ground cover than tall fescue and Kentucky bluegrass under reduced irrigation, but that they exhibited darker green color. We identified a large range of phenotypic values and generally high narrow sense heritability (h2>0.5) for turf quality within these species, particularly for thickspike and western wheatgrass. Selection for increased turfgrass quality in these wheatgrass species has a high likelihood of developing improved turfgrass cultivar in these species.

An Investigation of Trait Prioritization in Turfgrass Breeding Programs

The development and evaluation of new turfgrass cultivars require considerable resources. A systematic understanding of the breeders’ and distributors’ trait selection behavior can provide a basis for making adjustments and improvements based on industry needs and thus accelerate the breeding process and make it more efficient. The objective of this study is to investigate the selection priorities for turfgrass traits and identify the most influential factors affecting turfgrass breeders’ and distributors’ likelihood of selecting turfgrass traits. Results show that the most important trait clusters for both breeders and distributors were abiotic stress resistance and growth characteristics. Breeders were more likely than distributors to select appearance traits when setting trait priorities. Program characteristics such as program size, education level, and being a male respondent had positive effects on the reported likelihood of selecting studied turfgrass traits, and these effects varied for different trait clusters.

Breeding Cool‐Season Turfgrass Cultivars for Stress Tolerance and Sustainability in a Changing Environment

Growth and sustainability of cool‐season turfgrass species has the potential to be negatively impacted by future climate change; therefore, it will be necessary to breed turfgrass cultivars that have improved abiotic and biotic stress tolerance compared with cultivars that are currently available. This will require the use of techniques that can efficiently and effectively identify novel germplasm for incorporation into a breeding program. Over the past decade, advances have been made in the methodologies used to develop new cultivars of apomictic and open‐pollinated, cool‐season turfgrass species. This keynote address will discuss the impact climate change will have on plant breeding objectives, breeding techniques used by Rutgers University, and advances that have been made in breeding cool‐season grasses for improved abiotic and biotic stress tolerance.

Ecological Implications of Zoysia Species, Distribution, and Adaptation for Management and Use of Zoysiagrasses

The genus Zoysia Willd. comprises ±10 recognized species indigenous to the western Pacific Rim and Indian Ocean, which are collectively called “zoysiagrasses.” Three species—Z. japonica Steud., Z. matrella (L.) Merr., and Z. pacifica (Goudswaard) M. Hotta &amp; Kuroki (previously referred to as Z. tenuifolia)—plus interspecific hybrids have a long history of use as warm‐season perennial turf and ornamental grasses in many countries. Recently, cultivars from two other species, Z. macrantha Desv. and Z. sinica Hance, have also been developed. Breeders are currently exploring the potential to incorporate attributes from these and other Zoysia species into future zoysiagrass cultivars through hybridization. The attributes of Zoysia turfgrass cultivars—their strengths and limitations—can be related back to the species and germplasm from which they have been derived, and which (together with growth and development characteristics unique to the zoysiagrasses) ultimately determine their adaptation, use, and management. Differences in temperature, shade, drought, salinity, and traffic tolerance, as well as differences in nutritional and mowing requirements among zoysiagrasses, plus comparisons with Cynodon spp. turfgrasses, are highlighted.

Tall Fescue and Bermudagrass Cultivar Response to Water Stress at the Germination Growth Stage

Examining and developing screening techniques to identify drought‐resistant lines at the seedling stage is an important step for plant breeders. Therefore, the objectives of this research trial were to determine if the use of polyethylene glycol (PEG‐6000) is an effective tool to screen for water stress during seed germination and to determine potential cultivar differences within each species tested. Bermudagrass [Cynodon dactylon (L.) Pers.] cultivars selected included ‘Hollywood’, ‘Northshore’, ‘Riviera’, and ‘Transcontinental’. Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] cultivars included ‘Jaguar 4G’, ‘Quest’, ‘Summer’, and ‘Sundial’ as well as four experimental cultivars. Water stress levels were developed using PEG‐6000. For bermudagrass, seed was subjected to 0 (control), −2.5, −5.0, −7.5, and −10.0 MPa, while tall fescue water‐stress treatments included 0 (control), −2.0, −4.0, −5.0, and −7.0 MPa. Bermudagrass and tall fescue relative final germination rate (FGR) and relative daily germination rate (DGR) decreased with increasing concentrations of PEG‐6000. Regression analysis indicated that Sundial (−6.51 MPa) and Summer (−6.09 MPa) tall fescue and Transcontinental (−4.74 MPa) and Hollywood (−4.62 MPa) bermudagrass had the highest PEG concentration to reduce relative FGR by 50%. Results suggest PEG‐6000 is an effective technique for screening turfgrass cultivars that require less water for seed germination. This study also identified cultivars that would have a competitive advantage during the establishment phase if water is a limiting factor.

Reaction of Bentgrass Cultivars to a Resistance Activator and Elevated CO2 Levels When Challenged with Microdochium nivale, the Cause of Microdochium Patch

Climate change prediction models forecast increased CO2 levels and temperature changes. Microdochium nivale is a common pathogen of turfgrasses in temperate climates, and these changes may increase Microdochium patch disease severity. This research involved experiments on cultivars of Agrostis spp. and Poa annua inoculated with M. nivale and incubated under two CO2 concentrations. The efficacy of a resistance activator, Civitas + Harmonizer, was tested on eight cultivars that were grown under 400 or 800 ppm of CO2 during a 15°C/10°C (day/night), 16‐h photoperiod. The grasses were treated with water or Civitas + Harmonizer and inoculated 1 wk later with M. nivale. Disease severity was lower at 800 ppm than at 400 ppm of CO2, and the application of Civitas + Harmonizer decreased disease symptoms. This research will be useful for recommendations on turfgrass cultivars for northern temperate zone golf courses and on sustainable management practices to face the challenges of climate change.

Comparative Performance and Daily Light Integral Requirements of Warm‐Season Turfgrasses in Different Seasons

Shade or reduced sunlight poses a major challenge for maintaining acceptable turfgrass quality. The quantification of daily light integral (DLI, mol m−2 d−1) requirement could help to identify shade‐tolerant germplasm. The objectives of this study were (i) to compare turf performance, and (ii) to determine seasonal DLI requirement of 12 warm‐season turfgrass cultivars in response to varying levels of shade. A greenhouse study that included three experiments was conducted in spring (30/20°C), summer (35/25°C), and winter (25/15°C) months. Shade levels providing 33, 61, and 92% reductions in photosynthetic photo flux were imposed. Twelve cultivars from nine species were evaluated for turfgrass quality (TQ), normalized difference vegetation index, and shoot biomass production over 8 wk. The DLI requirement was obtained through nonlinear regression between DLI and TQ. Most warm‐season turfgrass species maintained acceptable TQ up to 33% shade. ‘TifGrand’ and ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt‐Davy] required each relatively higher DLI ranging from 9.2 (winter) to 21.4 (summer) mol m−2 d−1. Zoysiagrass (Zoysia spp.) cultivars maintained acceptable TQ up to 61% shade, with the lowest DLI requirements ranging from 5.9 (winter) to 10.9 (summer) mol m−2 d−1. The DLI requirements for the tested grasses were lower in winter (5.9–9.9 mol m−2 d−1) than in spring (9.4–17.4 mol m−2 d−1) and summer (9.9–21.4 mol m−2 d−1). ‘Argentine’ bahiagrass (Paspalum notatum Flugge) had an increased DLI requirement relative to other entries in summer months.

Association between Blissus insularis Densities and St. Augustinegrass Lawn Parameters in Florida

Core Ideas Cultural control of southern chinch bug in St. Augustinegrass by following recommended guidelines for mowing heights based on turfgrass cultivar, and practicing thatch management may reduce insecticide use and nontarget impacts. Turf parameters (turf height and thatch thickness) were closely associated to southern chinch bug densities observed in St. Augustinegrass residential lawns. Best management practices recommended for growing St. Augustinegrass in Florida may help to maintain a balance between turf health and pest pressure. Turf characteristics in conjunction with environmental factors influence the microclimate suitability for insect pest survival in grasses. In this study, we sought to find the association between southern chinch bug (Blissus insularis) densities, St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] health characteristics (weed abundance, turf density and height, turf color, chlorophyll content, total Kjeldahl nitrogen concentration, and thatch thickness), and abiotic factors (soil pH, soil and air temperature, soil moisture, and light intensity) by sampling residential lawns in Alachua and Marion counties, Florida. A 2‐year study was conducted: approximately 90 St. Augustinegrass lawns were selected for monthly sampling in May and June 2011. This was followed by weekly sampling in 17 selected lawns in July and August 2011 and 13 lawns in June to August 2012, respectively. Results from lawn surveys indicated that light intensity (r = 0.30, P = 0.0034), and thatch thickness (r = 0.22, P = 0.0390) were positively associated with B. insularis densities. The inverse relationship between turf color and B. insularis densities indicated the impact of insect feeding damage. A significant positive association of insect abundance with grass height and thatch thickness identified the need for turf management practices (mowing at recommended cut height and verticutting/thatch removal) to reduce habitat suitability for insect pest survival.