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Jack D. Fry

A field study was conducted in southern Louisiana to screen several plant growth regulators (PGRs) for efficacy in suppressing centipedegrass [Eremochloa ophiuroides (Munro) Hack.] vegetative growth and seedhead production. PGRs were applied in three sequential treatments in 1988 and included ethephon, glyphosate, mefluidide, paclobutrazol, sethoxydim, and sulfometuron methyl. Ethephon (5.0 kg·ha-1) suppressed mean centipedegrass vegetative growth by 15% with no turf injury. Mefluidide (0.6 kg·ha-1) and ethephon reduced mean seedhead number by 55% and 61%, respectively. Glyphosate (0.6 kg·ha-1) suppressed vegetative and reproductive growth, but caused unacceptable phytotoxicity and reduced centipedegrass cover and quality during Spring 1989. Use of ethephon or mefluidide to reduce trimming requirements or mower operation in hazardous areas may be an effective means of inhibiting centipedegrass growth. Chemical names used: N -(phosphonomethyl) glycine (glyphosate); N -[2,4-dimethyl-5-[[(trifluromethyl) sulfonyl]amino] phenyl]acetimide (mefluidide); 2-[1-(ethoxyimino)butyl] -5[2-(ethylthio) propyl]-3-hydroxy-2-cycIohexen-l-one (sethoxy-dim); 2-[[[[(4,6-dimethyl-2 -pyrimidinyl) amino] carbonyl]amino] sulfonyl]benzoic acid (sulfometuron methyl); (2-chloroethyl) phosphoric acid (ethephon); (±)-(R*R*)β-[(4-chlorophenyl)methyl]-α-(l,l-dimethylethyl) -1 H -l,2,4-triazole-l-ethanol (paclobutrazol).

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Yaling Qian and Jack D. Fry

Greenhouse studies were conducted on three warm-season turfgrasses, `Midlawn' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], `Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and `Meyer' zoysiagrass (Zoysia japonica Steud.), and a cool-season turfgrass, `Mustang' tall fescue (Festuca arundinacea Schreb.) to determine 1) water relations and drought tolerance characteristics by subjecting container-grown grasses to drought and 2) potential relationships between osmotic adjustment (OA) and turf recovery after severe drought. Tall fescue was clipped at 6.3 cm once weekly, whereas warm-season grasses were clipped at 4.5 cm twice weekly. The threshold volumetric soil water content (SWC) at which a sharp decline in leaf water potential (ψL) occurred was higher for tall fescue than for warm-season grasses. Buffalograss exhibited the lowest and tall fescue exhibited the highest reduction in leaf pressure potential (ψP) per unit decline in ψL during dry down. Ranking of grasses for magnitude of OA was buffalograss (0.84 MPa) = zoysiagrass (0.77 MPa) > bermudagrass (0.60 MPa) > tall fescue (0.34 MPa). Grass coverage 2 weeks after irrigation was resumed was correlated positively with magnitude of OA (r = 0.66, P < 0.05).

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Jack D. Fry and D. Wayne Wells

Field studies were conducted in south Louisiana to identify plant growth regulators that suppress carpetgrass (Axonopus affinis Chase.) seedhead development. In an initial study, best results were obtained with sethoxydim (0.11 kg·ha-1) and sulfometuron methyl (0.6 kg·ha-1), which reduced seedhead development by 88% and 86%, respectively, compared to untreated plots 21 days after treatment. Sulfometuron methyl caused unacceptable carpetgrass injury, however. Evaluation of seven sethoxydim application levels between 0 and 0.34 kg a.i./ha showed that carpetgrass seedhead number and elongation rate declined with increasing sethoxydim amount [SEEDHEAD NUMBER (m-2) = 515 – 1340 (kg), R 2 = 0.82; ELONGATION (cm) = 25.3 – 151 (kg) + 276 (kg2), R 2 = 0.77]. Carpetgrass seedhead production was restricted up to 6 weeks after sethoxydim (0.17 and 0.22 kg·ha-1) application. Chemical names used: (2-[1-(ethoxyimino)butyl]-5-[2-ethylthio)propyl)-3-hydroxy-2-cyclohexen-1-one) (seth-oxydim); (2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoic acid) (sulfometuron methyl).

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Alan J. Zuk and Jack D. Fry

Establishment of seeded `Zenith' zoysiagrass (Zoysia japonica Steud.) in an existing sward of perennial ryegrass (Lolium perenne L.) is difficult, and chemicals arising from perennial ryegrass leaf and root tissue may contribute to establishment failure. Experiments were done to evaluate zoysiagrass emergence and growth in soil amended with perennial ryegrass leaves or roots, or after irrigation with water in which perennial ryegrass leaves or roots had previously been soaked. Compared to unamended soil, soil amended with perennial ryegrass leaves at 12% and 23% by weight reduced zoysiagrass seedling number 20% and 26%, respectively; root area and mass were reduced 50% when amendments comprised 12% of soil weight. Similar reductions in zoysiagrass seedling emergence and growth were observed in a second soil amendment study, regardless of whether perennial ryegrass was treated with glyphosate or not. Soil mixed with perennial ryegrass leaves, but not roots, at 12% by weight had a high soil conductivity (5.1 dS·m–1), which could have contributed to reduced zoysiagrass emergence and growth. More than 50% fewer zoysiagrass seedlings emerged and root mass was up to 65% lower when irrigated with water in which perennial ryegrass leaves or roots at 5, 10, or 20 g·L–1 were previously soaked for 48 hours. Zoysiagrass leaf area, and root length and area, were also lower when irrigated with water previously containing perennial ryegrass roots. Perennial ryegrass leaves and roots have the capacity to inhibit emergence and growth of `Zenith' zoysiagrass seedlings, which could negatively affect stand establishment.

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Jack D. Fry and Ward S. Upham

In 1992 and 1993, 12 postemergence herbicide treatments were applied to field-grown buffalograss [Buchloe dactyloides (Nutt.) Engelm.] seedlings having 1 to 3 leaves and 2 to 4 tillers, respectively. The only herbicide treatments that did not cause plant injury at 1 or 2 weeks after treatment (WAT) or reduce turf coverage 4 or 6 WAT compared to nontreated plots (in 1992 or 1993) were (in kg·ha–1) 0.6 dithiopyr, 0.8 quinclorac, 2.2 MSMA, and 0.8 clorpyralid. Evaluated only in 1993, metsulfuron methyl (0.04 kg·ha–1) also caused no plant injury or reduction in coverage. Fenoxaprop-ethyl (0.2 kg·ha–1) caused severe plant injury and reduced coverage by >95% at 6 WAT. Dicamba reduced coverage by 11% at 6 WAT in 1992 but not 1993. The chemicals (in kg·ha–1) triclopyr (0.6), 2,4-D (0.8), triclopyr (1.1) + 2,4-D (2.8), 2,4-D (3.1) + triclopyr (0.3) + clorpyralid (0.2), and 2,4-D (2.0) + mecoprop (1.1) + dicamba (0.2) caused plant injury at 1 or 2 WAT in 1992 or 1993, but coverage was similar to that of nontreated turf by 6 WAT. Chemical names used: 3,6-dichloro-2-pyridinecarboxylic acid (clorpyralid); 3,6-dichloro-o-anisic acid (dicamba); (+/–)-2-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid (diclofop); 3,5-pyridinedicarbothioic acid, 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-S,S-dimethyl ester (dithiopyr); 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy] propanoate (fenoxaprop-ethyl); 2-(2,4-dichlorophenoxy)propionic acid (mecoprop); methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-amino]carbonyl]amino]sulfonyl]benzoate (metsulfuron methyl); monosodium salt of methylarsonic acid (MSMA); 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac); [(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid (triclopyr); (2,4-dichlorophenoxy) acetic acid (2,4-D).

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Jack D. Fry and Raymond A. Cloyd

Zoysiagrass, in general, has few insect pest problems but may suffer significant damage from infestations of the bluegrass billbug (Sphenophorus parvulus Gyllenhal). This study evaluated ‘Meyer’ and DALZ 0102 zoysiagrass (both Zoysia japonica Steud.) and 31 experimental zoysiagrass progeny, including reciprocal crosses between Z. japonica × Z. matrella (L.) Merr. or crosses between ‘Emerald’ (Z. japonica × Z. pacifica Goudsw.) × Z. japonica. These grasses were evaluated in adjacent experiments with 18 progeny in one and 13 in another. Plots were maintained under golf course fairway conditions and experienced natural infestations of the bluegrass billbug in 2009 and 2010 with larval damage primarily evident in June and continuing throughout the remainder of the growing season. ‘Meyer’ suffered the highest level of damage on each of six rating dates, ranging from 17% to 38% of the experimental plot area affected. Among the zoysiagrass progeny, damage ranged from 0% to 35% with most showing less than 15% damage. Overall, zoysiagrass progeny associated with reciprocal crosses of Z. japonica × Z. matrella or ‘Emerald’ × Z. japonica were less susceptible to bluegrass billbug than ‘Meyer’.

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Kenton W. Peterson, Jack D. Fry and Dale J. Bremer

‘Meyer’ zoysiagrass (Zoysia japonica Steudel) is commonly planted on home lawns and golf courses in the transition zone; however, poor shade tolerance limits its widespread use. This study was conducted to determine changes and differences in growth among selected Zoysia cultivars and progeny under a natural shade environment over a 3-year period in the transition zone. The study was initiated in June 2010 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Soil type was a Chase silt loam (fine, montmorillonitic, mesic, Aquic, Argiudoll). Zoysia genotypes were sodded in 0.37-m2 plots and arranged in a randomized complete block with five replications under silver maple (Acer saccharinum L.) shade that resulted in a 91% reduction in photosynthetically active radiation (PAR). Genotypes included ‘Zorro’ [Z. matrella (L.) Merrill], ‘Emerald’ [Z. japonica × Z. pacifica (Goudswaard) Hotta & Kuroki], ‘Meyer’, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella × Z. japonica), and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. ‘Zorro’ and ‘Emerald’ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in ‘Meyer’ from June 2010 to June 2012, but declines in [(Z. japonica × Z. pacifica) × Z. japonica] progeny were only 1% for Exp2 and 27% for Exp3, and both Exp2 and Exp3 maintained high percent green cover throughout the study. In general, by the third year of evaluation, progeny of [(Z. japonica × Z. pacifica) × Z. japonica] had higher quality ratings and higher tiller numbers than ‘Meyer’ and may provide more shade-tolerant cultivar choices for transition zone turf managers.

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Jack D. Fry, Steven C. Wiest and Ward S. Upham

Evapotranspiration from tall fescue, perennial ryegrass and zoysiagrass turfs during the summers of 1992-3 was compared to evapotranspiration estimates from an evaporation pan, a black Bellani plate, and several empirical combination models, Actual measurement of turf water use was made with small weighing lysimeters. Soil was maintained at field capacity. Data were collected on 51 dates between June and September. Tall fescue was clipped weekly at 7.6 cm whereas ryegrass and zoysiagrass were clipped 3 times weekly at 2.5 cm, Although differences between the grass species existed, in general the rankings of estimate precision were Bellani plate > evaporation pan > empirical models when compared with measured evapotranspiration rates.

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Steven C. Wiest, Jack D. Fry and Ward S. Upham

A relatively accurate estimate of turfgrass evapotranspiration (ET) using environmental parameters readily obtainable from a local weather station would be of benefit to golf course superintendents, landscape managers, and homeowners. The Penman–Monteith model is clearly a poorer estimate than that obtained by Bellani plates or spheres. It has been suggested that, while the Penman–Monteith model is good in the drier climate of the southwestern United States, other models may be of greater practicable utility in climates such as are common in Kansas. Thus, other models have been evaluated for their suitability as turfgrass ET estimates in Kansas-like climates. Turfgrass ET was measured via lysimeters in 1992–94. Specifically, measurements were taken on three tall fescue varieties mowed at 6.35 or 7.62 cm, and zoysiagrass and perennial ryegrass mowed at 2.54 cm. Evaporation from black Bellani plates was measured simultaneously. These evaporation and ET rates were compared to those estimated by various empirical models whose data came from a weather station located within 31 m of the Bellani plates and lysimeters. Empirical models included temperature methods (e.g., FAO-24 Blaney–Criddle), radiation methods (e.g., Jensen–Haise, Hargreaves–Samani), combination equations (e.g., Priestly–Taylor, Penman), and variants. The best model(s) determined from these comparisons will likely become the method(s) of choice for estimating turfgrass ET in Kansas.