Kevin E Kenworthy

University of Florida | UF · Department of Agronomy

Warm-season perennial grasses are the backbone of the pasture-based livestock industry in the lower southeastern United States, and bermudagrass (Cynodon spp.) is the most widely planted forage species, covering ∼15 million ha. The genus Cyn-odon is native to southern Africa, and germplasm collections possess high genetic and phenotypic variability...

‘DALSA 1618’ (Reg. no. CV‐291, PI 702594) is a first‐generation intraspecific St. Augustinegrass [ Stenotaphrum secundatum (Walt.) Kuntze] hybrid developed by Texas A&M AgriLife Research in Dallas, TX, from a cross between a drought‐resistant polyploid female parent, TAES 5384 (PI 300130, GRIN National Plant Germplasm System), and a semi‐dwarf shad...

Background Drought‐tolerant turfgrass cultivars are becoming more important each year as landscape irrigation practices are becoming more restrictive. Methods In this study, we quantified the level of drought tolerance (DT) in perennial ryegrass and tall fescue genotypes across years under different mowing (MH) and fertility (FL) rates. A total of...

Bahiagrass (Paspalum notatum Flüggé) cultivars used for forage in the southeastern US are primarily diploids. While producers favor tetraploid traits, e.g., wider leaf blades and fewer inflorescences, compared to diploids, there are barriers to their greater use including apomictic reproduction, lesser frost tolerance, and later initiation of sprin...

La grama zoysia se introdujo en los Estados Unidos desde Asia y proporciona un césped atractivo en gran parte de los Estados Unidos. En los últimos años han ingresado al mercado nuevos cultivares de grama zoysia con una mejor resistencia a insectos, un establecimiento acelerado y un mejor rendimiento en general. Written by J. Bryan Unruh, Marco Sch...

‘FL4XR16’ (Reg. no. CV‐289, PI 699961) tetraploid forage‐type annual ryegrass (Lolium multiflorum Lam.) is a synthetic cultivar selected for mid‐late maturity, high dry matter (DM) yield, and resistance to gray leaf spot (GLS). In spring 2016, a nursery of ‘FL Red’ experienced a high incidence of GLS, and 50 highly disease resistant individual plan...

As the earth's climate changes, the ability of breeders to select for traits within forage species that impart adaptability to these changes will be critical for the maintenance of grassland agricultural systems. Temperate ‐ tropical climate transition zones (between 27 and 31° N and S latitude) have proven to be ideal zones for breeding species wi...

Zoysiagrasses were introduced into the United States from Asia and provide attractive turf throughout much of the United States. In recent years, newer cultivars of zoysiagrass have entered the market with improved insect resistance, accelerated establishment, and better overall performance. This 8-page major revision of the Environmental Horticult...

Growing urban populations have placed greater demands on municipal water supplies, especially during dry periods. Efforts are underway to develop turfgrasses with better performance using less irrigation. The objective of this research was to assess the effects of irrigation management and St. Augustinegrass (Stenotaphrum secundatum (Walter) Kuntze...

Mowing is a key input required to maintain a turfgrass lawn but has an environmental impact and represents a repetitive expense for home and business owners. In an effort to reduce canopy growth rate and to improve weed control, genetically modified St. Augustinegrasses (Stenotaphrum secundatum (Walter) Kuntze) derived from the cultivar ‘Floratam’...

Esta publicación está destinada a propietarios de casas y encargados de céspedes que manejan grama Bahía en el paisaje de Florida.This new 6-page translation of the UF/IFAS Environmental Horticulture Department was written by Marco Schiavon, J. Bryan Unruh, Kevin E. Kenworthy, y Henrique Mayer.https://edis.ifas.ufl.edu/lh084

Bahiagrass (Paspalum notatum Flugge) was introduced from Brazil in 1914. It was originally used as a pasture grass on the sandy soils of the southeastern United States. Additional varieties have been introduced since that time for use as lawn grasses. Bahiagrass is a low-maintenance lawn grass that does well with limited water and fertilizer inputs...

Increasing urban growth has placed a strain on limited potable water resources. Therefore, improved drought tolerance in turfgrass is important to reduce the need for supplemental irrigation to maintain the aesthetic value and functionality of turfgrass areas. Field evaluations are subject to variability in irrigation patterns, wind, soil, and drai...

During periods of drought, the irrigation needs of current warm‐season turfgrass cultivars and frequent municipal water use restrictions present a major challenge to the turfgrass industry. Turfgrass breeding programs have responded by placing more emphasis on improved drought response. During 2012–2013, 560 genotypes of four warm‐season turfgrass...

Species resiliency to climate change is critical for sustainability of grassland agricultural systems. Transition zones between temperate and tropical climates (between 27 and 31° N and S latitude) with variable annual frost/freeze events have proven to be ideal zones for identification of species with variable climate adaptation. This paper will i...

Several new bermudagrass cultivars are available and commonly used on golf course fairways. However, little is known about their cultural requirements or how these cultivars perform under lower inputs regimes. A 2‐year study was conducted at University of Florida, Fort Lauderdale Research and Education Center, to assess performance of four hybrid b...

La grama o césped St. Augustine (Stenotaphrum secundatum [Walt.] Kuntze) está muy adaptada a las zonas calurosas y húmedas (subtropicales) del mundo. Se cree que es nativa de las regiones costeras del Golfo de México y del Mediterráneo. St. Augustine es la especie de grama más usada en Florida (Figura 1). Esta publicación está destinada a propietar...

This publication provides the most up-to-date information on adapted cool-season forage varieties. Written by M. Wallau, A. R. Blount, E. Rios, J. M. B. Vendramini, J. C. B. Dubeux, Md. A. Babar, K. E. Kenworthy, M. Mulvaney, and K. H. Quesenberry, and published by the UF/IFAS Agronomy Department, revised August 2021.

St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze) is widely adapted to the warm, humid (subtropical) regions of the world. It is believed to be native to the coastal regions of both the Gulf of Mexico and the Mediterranean. St. Augustinegrass is the most commonly used lawn grass in Florida (Figure 1). This publication is intended for home...

Herbicide management information is lacking for recently developed turf-type bahiagrass germplasm. The objective of this study was to evaluate the herbicide tolerance of nine experimental bahiagrass genotypes compared to the industry standard ‘Argentine’. The experimental entries included Argentine and ‘Wilmington’ mutants, and wild-type breeding l...

Current recommended nitrogen (N) fertilization rates for St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] in South Florida range from 4 to 6 lb. N 1000 sq. feet−1 yr−1, applied throughout the year. Nevertheless, strict fertilizers ordinances are being passed by multiple counties in FL, setting limits to the amount of N that can be appli...

St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a turfgrass extensively used in managed landscapes in Florida and throughout the SE USA. To develop cultivars with broad adaptation, it is necessary to understand the effect of genotype by environment interaction (GEI). The objective of this study was to estimate genetic parameters in...

Shade caused by trees or buildings can affect the quality and growth of turfgrasses. Thus, breeding for shade tolerance is an essential component of most turfgrass improvement programs. The objective of this study was to evaluate the performance of seashore paspalum (Paspalum vaginatum Sw.) breeding lines under shade in multi-environment trials. Ge...

Bermudagrass (Cynodon spp.) is a forage and turf crop commonly used worldwide. The USDA bermudagrass germplasm set is composed of plant introductions (PI’s) collected around the world and contains different Cynodon species, primarily C. dactylon. The collection was screened in a replicated trial in Florida for forage yield, leaf width, nutritive va...

St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a commonly used warm‐season turfgrass for lawns in warm‐humid to tropical climates. Efforts to breed improved cultivars with enhanced abiotic and biotic stress tolerance are ongoing, but additional data on their growth and adaptation is needed. Twenty‐one commercially available St. Aug...

As awareness of environmental impacts of anthropogenic ecosystems increases, low input turfgrass species like bahiagrass (Paspalum notatum Flügge) may become more prominent in urban landscapes and on golf courses. A study was conducted at the West Florida Research and Education Center, Jay, FL, USA, to evaluate the performance of novel turf‐type ba...

In breeding programs, superior parental genotypes are used in crosses to generate novel genetic variability for new selection cycles. Genotypes are usually more adapted to environments where the breeding program is located, since selections are performed under specific agroecosystems. Thus, the objective of this study was to evaluate the performanc...

Perennial warm-season pasture grasses used in Florida become dormant in late fall and winter because of short days, cooler temperatures, and frosts. Many livestock producers may choose to establish cool-season annual pasture species to supplement their forage production. These plants are usually higher in total digestible nutrients (TDN) and crude...

All known species of zoysiagrass are tetraploids (2n = 4x = 40) but octoploids have been reported. This research was conducted to evaluate ploidy variability from a stand of zoysiagrass where an 8x clone (E11) originated, and to characterize progeny from E11 and other ploidy variable clones. Clone ploidy was determined by flow cytometry and clones...

Estimation of genotype-by-environment interaction (GEI) is important in breeding programs because it provides critical information to guide selection decisions. In general, multi-environment trials exhibit heterogeneity of variances and covariances at several levels. Thus, the objectives of this study were to: (i) find the best genetic covariance m...

Bahiagrass (Paspalum notatum Flüggé) is the most extensively cultivated perennial warm‐season grass in the Southeastern US for pasture, utility turf, cover crop and soil stabilization. The UF‐IFAS Bahiagrass Breeding Program has recently selected several improved forage and dwarf turf‐type tetraploid breeding lines. However, seed production and see...

‘DALZ 1308’ (Reg. no. CV‐285, PI 691612) is a first‐generation interspecific hybrid developed in 2004 by crossing a genotype of Zoysia minima (Colenso) Zotov and Z. matrella (L.) Merr. ‘Diamond.’ After field evaluations in Dallas, TX (2004–2009) and Gainesville, FL (2006–2008), DALZ 1308 was selected for advancement to the 2013 Warm‐season Putting...

Plant-parasitic nematodes are devastating pathogens of many important agricultural crops. They have been successful in large part due to their ability to modify host plant metabolomes to their benefit. Both root-knot and cyst nematodes are endoparasites that have co-evolved to modify host plants to create sophisticated feeding cells and suppress pl...

Every county and municipality in Florida can adopt its own unique ordinance regulating the fertilization of lawns and landscapes. With increased concern for eutrophication to state waterbodies, many have chosen to implement seasonal fertilizer restrictive periods prohibiting the application of nitrogen and phosphorus fertilizers, typically during t...

This publication provides the most up-to-date information on current adapted cool-season forage varieties. The recommendation of varieties is based on multi-location, multi-year cultivar evaluation experiments that may include trials in Georgia and other states. Table 1 includes information about the planting dates, seeding rates, and other conside...

Aryloxyphenoxypropionate (AOPP) herbicides, such as fluazifop‐P‐butyl, can be used for postemergence control of grassy weeds in zoysiagrass ( Zoysia spp.), although the turf might suffer transient injury. This injury can be reduced by tank mixing fluazifop‐P‐butyl with triclopyr, an herbicide that behaves as a safener for AOPP herbicides. To charac...

Zoysia germplasm exhibit different levels of sensitivity to fluazifop-P-butyl, but the genetic factors responsible for such differences are unknown. Segregation patterns of the fluazifop-P-butyl tolerance trait were studied under greenhouse conditions. In total, 244 F 1 lines were generated from multiple crosses between the tolerant line 5337-2 (no...

Characterizing phenotypes in germplasm collections and making data publicly available is crucial to ensure their utilization in breeding programs. Variance component estimates are used to calculate genetic parameters needed to make strategic decisions for germplasm conservation and its utilization in plant breeding. This information is lacking for...

Breeding herbicide tolerance into new cultivars can improve safety and weed control in turfgrass systems. The sensitivity to fluazifop-P-butyl of 27 zoysiagrass ( Zoysia spp.) lines was screened under greenhouse conditions to identify potential tolerant germplasm for breeding programs. The herbicide rate that caused 50% biomass reduction (GR 50 ) a...

Recent advances in remote sensing technology, especially in the area of Unmanned Aerial Vehicles (UAV) and Unmanned Aerial Systems (UASs) provide opportunities for turfgrass breeders to collect more comprehensive data during early stages of selection as well as in advanced trials. The goal of this study was to assess the use of UAV-based aerial ima...

The cover image, by Jing Zhang et al., is based on the Drought Stress article Drought responses of above‐ground and below‐ground characteristics in warm‐season turfgrass. https://doi.org/10.1111/jac.12301.

Core Ideas Nitrogen rate had a greater impact on turfgrass quality of zoysiagrass when the grass was actively growing, but the effect of mowing height was only significant during spring green‐up. Nitrogen rate of 171 kg ha ⁻¹ was suitable for consistent turf performance in zoysiagrass and the effect of increasing N rate from 171 to 268 kg per ha wa...

The Tifton Turfgrass Breeding Program has a long history of releasing high quality turfgrass varieties. Today, the goal of the program is to create turfgrasses that are adapted to a broader range of environments and have improved drought and traffic tolerance. The latest commercial turfgrass release from Tifton is DT-1, an interspecific triploid (2...

Water shortages have become more chronic as periodic droughts prolong and water demand for urban and agricultural use increases. Plant drought responses involve coordinated mechanisms in both above‐ and below‐ground systems, yet most studies lack comparisons of root and canopy responses under water scarcity and recovery. This is particularly true o...

Although it is known that drought tolerance can be associated with membrane fatty acid (FA) unsaturation, a relevant study is lacking in zoysiagrass (Zoysia spp.) and St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze.]. Our objectives were (i) to substantiate that variation exists among species and genotypes for leaf tissue FA composition...

Randomized complete block (RCB) design is the most widely used experimental design in biological sciences. As number of treatments increases, the block size become larger and it looses the capacity to control the variance within block, which is its original purpose. A method known as post hoc blocking could be used in these cases to improve the gen...

Characterization of rooting capacity in the greenhouse is a routine screening procedure for assessing a plant’s ability to cope with drought stress. However, an association between rooting capacity in the greenhouse and turf performance in the field during drought is not always found. The objectives of the study were (i) to classify zoysiagrass (Zo...

Two diseases of St. Augustinegrass (SAG) [Stenotaphrum secundatum (Walt.). Ktze.] are caused by different anastomosis groups (AGs) of Rhizoctonia solani. Brown patch (BP) is a foliar disease of little economic importance, and large patch (LP) causes leaf sheath rot and death of affected turfgrass shoots and stolons. St. Augustinegrass genotypes wer...

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...

Since its introduction into the United States in 1892, zoysiagrass (Zoysia spp. Willd.) has made a tremendous impact on the US turfgrass industry. Three species of zoysiagrass [Z. japonica Steud., Z. matrella (L.) Merr., and Z. pacifica (Goudswaard) M. Hotta & S. Kuroki] collected from East Asia and the Pacific Islands were introduced into the Unit...

A study describing the overall physiological responses to drought and exploring the underlying mechanisms in multiple turfgrass species and genotypes is needed to make improvements in breeding for turfgrass species that are tolerant to water-limiting conditions. The objective of this study was to compare the differential canopy and physiological re...

The development of a turf-type bahiagrass could have a remarkable impact on the billion-dollar turf industry in the south-eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included muta...

Water and fertilizer regulations in Florida have created a market for low‐maintenance grasses. The objectives of this study were to compare rooting and turf performance of three selected turf‐type bahiagrass lines (‘M36’, ‘WEMS12’, and ‘FLDW51’), in comparison with ‘Wilmington’ and ‘Argentine’ bahiagrass, and ‘Floratam’ St. Augustinegrass, grown un...

Seashore paspalum ( Paspalum vaginatum Schwartz) is a warm‐season turfgrass noted for its salt tolerance and is used on golf course fairways and greens. Dollar spot ( Sclerotinia homoeocarpa F.T. Benn.) is an important disease of seashore paspalum, causing distinct silver dollar‐sized necrotic patches to form on the turf. Previous research by Flor...

Carpetgrasses ( Axonopus spp.) have been used as home lawn, sports, and amenity turfgrasses in many locations around the world. Only limited efforts have focused on genetic improvement of Axonopus for turf. Before initiating any genetic improvement program, knowledge of ploidy differences within and among species in a germplasm collection is critic...

Zoysiagrasses (Zoysia spp.) are perennial, warm-season turfgrass species well-adapted for home lawns, commercial landscapes, and golf courses in warm or transitional climates. They are versatile species with great potential as low-input turf because of their moderate drought and shade tolerances. While zoysia species have been found to have fewer m...

Understanding phenotypic plasticity and pat­terns of biomass allocation of turfgrass under shade is needed for better turfgrass manage­ment and the development of cultivars that per­sist under shade. The objectives of this study were to (i) compare turf performance and deter­mine the relationship between the phenotypic plasticity in growth, biomass...

Use of bermudagrass (Cynodon dactylon) cultivars resistant/tolerant to plant-parasitic nematodes is an important component of integrated pest management (IPM) for sustainable turf nematode management in sandy coastal soils of the Southeastern United States. A multi-year field experiment evaluated five bermudagrass genotypes [‘Tifway’, standard susc...

‘FL PE’ (Reg. No. CV-280, PI 675350) diploid annual ryegrass (Lolium multiflorum Lam.) is a synthetic cultivar selected for later maturity, excellent cold tolerance, and resistance to crown rust (caused by Puccinia coronate Corda) and gray leaf spot (caused by Pyricularia grisea Sacc.) It offers sufficient cold tolerance to be grown in the northern...

‘FL Red’(Reg. No. CV-281, PI 678572) tetraploid annual ryegrass (Lolium multiflorum Lam.) is a synthetic cultivar selected for later maturity and resistance to annual ryegrass crown rust caused by Puccinia coronata Corda and gray leaf spot caused by Pyricularia grisea Sacc. FL Red was synthesized originally in 2004 from equal quantities of ‘Jumbo’,...

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...

Irrigation for commercial and residential turf is becoming limiting, and water scarcity is one of the long-term challenges facing the turfgrass industry. Potential root development and profile characteristics of turfgrass provide important information regarding their drought resistance mechanisms and developing drought-resistant cultivars. The obje...

‘NUF-76’ (Reg. No. CV-276, PI 674513) St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] was developed from a series of complex crosses and is suitable for use as a turfgrass in lawns in the southern United States. It is resistant to southern chinch bug (Blissus insularis Barber) biotypes in Florida and North Carolina, is the first diploid...

Annual ryegrass (Lolium multiflorum Lamarck) is planted annually on more than 1 million ha of pastures in the southeastern United States. The exact ploidy level and genome size of the annual ryegrass germplasm collection (USDA-ARS, Germplasm Resources Information Network - GRIN) are unknown and the future use of this germplasm relies on their deter...

In Florida, St. Augustinegrass (Stenotaphrum secundatum) is the most commonly used turfgrass species. Sting nematode (Belonolaimus longicaudatus) is recognized as a limiting factor to St. Augustinegrass in Florida, where 'Floratam', a polyploid, is the predominant cultivar; although the use of new diploid cultivars is increasing. The objective of t...

Seed production is a critical component in agricultural systems based on bahiagrass and ergot has been reported to significantly reduce seed quality in tetraploid cultivars. Seed yield and quality are important traits to evaluate in the advanced breeding lines developed at the University of Florida. Resistance to ergot was assessed in seven tetrapl...

Southern crabgrass is a common turfgrass weed throughout the United States, and in Florida a troublesome problem in St. Augustinegrass lawns. Because of herbicide label changes and lack of herbicide tolerance, no POST herbicides are currently registered for homeowner use for crabgrass control in residential and commercial St. Augustinegrass lawns....

Periodic drought, irrigation requirements, and the enforcement of mandatory watering restrictions have posed a challenge for homeowners and landscape managers to maintain acceptable turf quality during dry periods. Information regarding irrigation requirements and performance of common turfgrass species used for residential and commercial landscape...

Bahiagrass (Paspalum notatum Flugge) is extensively used in pastures in the southeastern US due to its adaptive characteristics to subtropical conditions. An increasing demand for attractive landscapes maintained with minimum inputs warrants improving the aesthetic value of bahiagrass. Breeding strategies differ for diploid and tetraploid bahiagras...

This revised 4-page fact sheet provides the most up-to-date information on current adapted varieties of cool-season forages. The recommendation of varieties is based on multi-location, multi-year cultivar evaluation experiments that may include trials in Georgia and other states. Table 1 includes information about the planting dates, seeding rates,...

ADDITIONAL INDEX WORDS. flow cytometry, octoploid, simple sequence repeat markers, Zoysia ABSTRACT. Zoysiagrass (Zoysia sp.) is used as a warm-season turfgrass for lawns, parks, and golf courses in the warm, humid and transitional climatic regions of the United States. Zoysiagrass is an allotetraploid species (2n = 4x = 40) and some cultivars are k...

The hunting billbug, Sphenophorus venatus vestitus Chittenden, is a pest that damages stems, rhizomes, and roots of zoysiagrass through a combination of adult and larval feeding. Management of this pest is difficult because it has multiple, overlapping generations in the southern United States, and symptoms of infestations are often misdiagnosed an...

Common carpetgrass is a warm-season grass species that is commonly used as a pasture grass in Louisiana and as an alternative low-maintenance lawn grass in the southern Unites States. Understanding genetic variation for traits related to seed production is important to determine breeding strategies for improvement. Ten genotypes were analyzed for n...

Characterization of Fluazifop-P-butyl Tolerance in Zoysiagrass CultivarsPOST control of grass weed species and contaminant turfgrass species, such as common and hybrid bermudagrass, is a major challenge in zoysiagrass. Fluazifop-P-butyl is a POST herbicide that can provide selective grass weed control with limited injury to zoysiagrass. However, be...

Forage legumes and grasses provide the basis for the worldwide ruminant animal livestock industry, and most of these forages come from perennial pasture plants. As animal agriculture has intensified, pest pressures on perennial forages often also become more prevalent. Among these pest plant parasitic nematodes, especially root-knot nematodes (RKN)...

‘DALSA 0605’ (Reg. No. CV-274, PI 671959) is an embryo rescue-derived interploid hybrid of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] resulting from a cross between TAES 5382 (African triploid PI 291594) and ‘Palmetto’ (diploid). DALSA 0605 was evaluated under the designation TAES 5471-18 and TXSA 19 and was approved for release as...