Adaptation, Management and Use of Warm-Season Turfgrasses Season Turfgrasses Adaptation, Management and Use of Warm-Season Turfg
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21/03/2011 Despite the efforts of modern advertising... Adaptation, management and use of warmwarm--seasonseason turfgrasses ■ There is no such thing as a perfect turfgrass − And there never will be ■ There is no one grass that is best for all uses in all situations and at all locations Dr Donald S. Loch (University of Queensland & GeneGro Pty Ltd) Choosing a turfgrass Management ■ Forget what is trendy ■ Choose a well adapted grass − Put promotional “information” into perspective − Easier to manage − Cheaper to manage − Better turf quality ■ Look at the use required (e.g. less weed invasion) ■ Understand your plant and work with it ■ Choose the best adapted grass for that use under the − ScienceScience--basedbased information climatic and soil conditions on your site (e.g. physiology, ecology, nutrition) ■ Concentrate on overcoming weaknesses − Strengths take care of themselves Marketing ‘information’ The tropical challenge ■ Most warmwarm--seasonseason grass varieties from North America, ■ “...sales information is what gets repeated over and over etc, have not been developed for tropical conditions until it is accepted as fact - not always accurate” − Periods of heat, humidity, rain (irregular mowing), heavy cloud cover, low light, high pest & disease pressure − Mllitith4Monsoonal climates with 4-8thd8 month dry season (need good drought tolerance or unlimited irrigation) ■ Develop better adapted “local” varieties − e.g. most greensgreens--qualityquality bermudagrasses from about 3030°° latitude − NovotekTM developed in north Queensland tropics (17(17°° latitude) ■ Make greater use of Asian species and germplasm 1 21/03/2011 Outline of presentation Cynodon dactylon (bermudagrass) ■ Summarise strengths & weaknesses of the major species ■ Most widely used warm-warm-seasonseason turfgrass ■ Explore underlying factors leading to adaptation ■ Strengths − Climatic (temperature, drought, shade) − Spreads rapidly by stolons and rhizomes − Soils (salinity) − Good drought tolerance − Wear − Fair to good wear tolerance − Organoarsenate herbicides used to control most other grasses ■ Introduce some minor species and their attributes ■ Weaknesses ■ Turf quality vs. sod price − Few varieties adapted to tropical conditions − Poor shade tolerance − Morphological considerations − High N requirements − Varietal contamination (seed, vegetative survivors) ■ Quality assurance − Organoarsenate herbicides to be phased out in 2014 − An unnecessary expense or value for money? Cynodon dactylon X transvaalensis Paspalum vaginatum (seashore paspalum) (hybrid bermudagrass) ■ MediumMedium--&& finefine--texturedtextured genotypes for fairways & greens ■ Former “niche” species well promoted over past decade ■ Strengths ■ Strengths − Vibrant green colour (the “wow” factor) − Sterile hybrids (do not set fertile seeds) − High salinity & waterlogging tolerance − Greater shoot densities than C. dactylon − Possible to plant a single variety wallwall--toto--wallwall − Can be mown shorter than C. dactylon − Finer textured turf than C. dactylon ■ Weaknesses − Expensive to manage in nonnon--salinesaline situations (competition) ■ Weaknesses − Limited range of herbicides (none for grass control) − Best adapted to warm temperate & subtropical conditions − Poor shade & drought tolerance − Need intensive management − Slow to recover from damage (scalping, drought thinning) − Genetically unstable (mixture of two different genomes) − Higher N requirements than promoted − Mutate vegetatively particularly when under stress − Risk of varietal contamination from seed − Finer stems do not mow as well as C. dactylon at higher levels − Disease susceptibility (e.g. dollar spot under low fertility) Drought Weed invasion after drought Scalping Scalping 2 21/03/2011 Sporobolus virginicus Dollar Spot Dollar Spot Paspalum vaginatum Rhizoctonia Large Patch Armyworm damage Axonopus compressus Digitaria didactyla ((serangoonserangoongrass) (broadleaf carpetgrass) ■ MediumMedium--texturedtextured stoloniferous grass for low fertility sites ■ CoarseCoarse--texturedtextured grass for shaded roughs, parks, etc − Similar to Queensland blue couch & Swazi grass (Australia) − Called “cow grass” when mixed with Paspalum conjugatum, etc ■ Strengths ■ Strengths − TlToleran t o f ac idifid infer tile soil s − Tolerant of acid infertile soils − Good drought tolerance − Good shade & disease tolerance − Useful herbicide tolerance (e.g. fluazifop for other grasses) − Vegetative sod strengthened by bermudagrass contaminant − Moderate shade tolerance (Qld blue couch poor shade tolerance) (also gives better cool season growth) − Mows easily even if allowed to grow long (soft grass) ■ Weaknesses − Clippings stick together when mowing moist grass ■ Weaknesses − Poor ball lie (sits down among foliage) − Poor drought & wear tolerance − Susceptible to Fe deficiency after heavy rainfall − Susceptible to Fe deficiency after heavy rainfall (easy & cheap to remedy with FeSO4) − Low temperatures restrict growth more than other turf grasses − Fair wear tolerance Zoysia spp. (zoysiagrass) Zoysia japonica (Japanese lawngrass) ■ Low maintenance grasses for fairways, tees & greens ■ CoarseCoarse--mediummedium textured genotypes for fairways & roughs − Originates from subtropical & temperate areas ■ Strengths − Low nutritional requirements ■ Strengths − Less mow ing than o ther grasses (l(slow grow th) − BlueBlue--greengreen colour (similar to serangoon grass) − Good drought tolerance − Fair shade tolerance − Few pests and diseases − Fair salinity tolerance − Tolerant of a wide range of herbicides (several for grass control) − Lower thatch development than Z. matrella − Good ball lie (sits up) − Tolerant of high strength soils − Highly resistant to wear ■ Weaknesses ■ Weaknesses − Slow growth (longer sod production cycle than for other species) − Susceptible to zoysia rust ((PucciniaPuccinia zoysiaezoysiae)) − Sharpen mower blades more often (high silica content) − Tolerates temporary, but not permanent, waterlogging − Slow to recover from scalping 3 21/03/2011 Zoysia matrella ((ManilagrassManilagrass)) Temperature adaptation – Cynodon varieties ■ MediumMedium--&& finefine--texturedtextured genotypes for fairways & greens ■ Optimum temperature related to area of origin − More tropical in origin than Z. japonica ■ Stronger winter dormancy in genotypes from colder areas ■ Strengths − Bright green colour (varies with variety) ■ WtWarm tempera te (Me lbourne – 13. 4°ClC annual average ) − High shade tolerance − Victorian > NSW & Queensland varieties (VGA(VGA--RedlandsRedlands research) − High salinity tolerance − Tolerant of high strength soils ■ Subtropical (Brisbane – 20.520.5°°CC annual average) − Not affected by zoysia rust ((PucciniaPuccinia zoysiaezoysiae)) − Queensland & NSW > Victorian varieties (Redlands research plots) − Close to the warmer limit for Cynodon hybrids ■ Weaknesses − Thatch development ■ Tropical (Cairns – 24.824.8°°C,C, Darwin – 28.128.1°°CC annual averages) − Also need tolerance of long periods of heavy cloud & low light − Slower green speeds than bermudagrass − Very few well adapted Cynodon varieties − Tolerates temporary, but not permanent, waterlogging − Local versions best (e.g. from ‘Greenlees‘Greenlees Park’) Cazaly’s Stadium (Cairns) TIO Stadium (Darwin) – local version of ‘‘GreenleesGreenlees Park’ ––LegendLegend® from Victoria Disease susceptibility ■ Disease tolerance related to area (climate) of origin – e.g. Bermudagrass accessions from dry (less humid) areas more susceptible to leaf diseases (UQ Australia-Australia-widewide germplasm collection) White leaf mycoplasmaBermudagrass smut ■ Disease control − Adds to management costs − Compromises turf quality ■ Greater emphasis on selecting new varieties for disease tolerance if available Bermudagrass rust Zoysia rust 4 21/03/2011 Water use efficiency OR drought tolerance? Paspalum vaginatum ■ Water use efficiency − Amount of water required to produce 1 unit of dry matter ■ Drought tolerance − What happens in absence of rain & irrigation (survival and how well it survives) ■ Total irrigation (e.g. desert conditions) − Water use efficiency Cynodon dactylon − Small savings in water use are possible ■ Strategic irrigation (e.g. irregular or seasonal rainfall) − Drought tolerance − Large savings in water use are possible by reducing frequency Physiological drought tolerance – Yi Zhou (UQ) Depth of rooting ■ Shade stress affects approx. 25% of turfgrass plantings − Trees & buildings in the landscape − Sports stadiums − Cloudy or hazy conditions 5 21/03/2011 Screening for salt tolerance Some “shady” facts ■ Measure Photosynthetically Active Radiation (PAR) − 400400--700700 nm wavelength band ■ 70% of daily radiation − 9:00am to 3:00pm (summer) − 10:00am to 2:00pm (winter) − Meeting light requirements for a turfgrass depends on when light is received, not just a fixed number of hours ■ Heavy dappled tree shade − c. 2020--40%40% of full sunlight ■ Building shade (e.g. elite sports stadiums) − c. 10% of full sunlight Screening perennial turfgrasses for Salinity growth response over time salinity tolerance TwoTwo--stagestage process (Rana MunnsMunns,, 1993) Three stages: – physiological drought (osmotic effect) for first 4 wk 1. establishment of vegetative material in pots – transition from physiological drought to toxic ion effects (salt(salt--freefree conditions) (4(4--66 wk after treatment) 2. transition to salinity treatments – toxic ion effects reduce DM production (progressively add salt over 11--33 wk period) (6+ wk) 3. experimental