The stoloniferous-rhizomatous growth habit of bermudagrass [Cynodon dactylon (L.) Pers.] is a key feature for fast turf establishment and effective recovery from wear and divots. Trinexapac-ethyl (TE) is a plant growth regulator used extensively to reduce the need for mowing. However, vertical growth suppression of vertical growth has the potential to reduce horizontal growth. Furthermore, side effects reported on several physiological functions could affect node ability to generate new plants. In a greenhouse trial, ‘Tifway’ hybrid bermudagrass (C. dactylon × C. transvaalensis Burtt Davy) grown in pots was treated with increasing rates of TE (untreated control, 0.015, 0.075, 0.150, and 0.300 g·m−2). The treatment effects on the number of stolons produced and their linear growth rate, node production, node vitality, and daughter plant characteristics were investigated. The effects of growth inhibition because of TE application on nodes and daughter plants and the relative duration were also assessed. Starting from 2 weeks after treatment (2 WAT), TE application resulted in reductions of stolon length of 24.6% and 52.9% compared with the untreated control, while at 3 and 4 WAT only 0.150 and 0.300 g·m−2 application rates produced significant reductions in stolon length with values of 37.1% and 52.9% at 3 WAT and of 34.1% and 48.3% at 4 WAT, respectively. The number of nodes per stolon was unaffected by treatments. No effect was observed in node vitality but daughter plants showed a postinhibition growth enhancement when nodes were excised at 4 WAT. TE application at the labeled rate did not affect the number of stolons produced by ‘Tifway’ hybrid bermudagrass compared with untreated control, while a reduction in stolon growth rate was recorded only at 2 WAT. Application at higher rates reduced stolon growth rate longer than labeled rate but not stolon production. None of the treatments reduced the number of vital nodes. Application rates higher than labeled rate produced a postinhibition growth enhancement in plants that originated from nodes excised at 4 WAT.
Marco Volterrani, Simone Magni, Monica Gaetani and Filippo Lulli
Michael D. Richardson, John McCalla, Tina Buxton and Filippo Lulli
Many early spring bulb species are naturally found in grassy areas such as meadows or lawns. However, few studies have been conducted to define this concept in maintained lawns, especially warm-season lawns such as zoysiagrass (Zoysia japonica) or bermudagrass (Cynodon dactylon). Four early spring bulb species, including two crocus species (Crocus tommasinianus ‘Ruby Giant’ and Crocus chrysanthus ‘Goldilocks’), reticulated iris (Iris reticulata ‘Cantab’), and snowdrop (Galanthus elwesii) were established in a zoysiagrass lawn site in Fall 2010. In Spring 2011 and 2012, five common preemergence herbicides used on lawns were applied across the plots to determine phytotoxicity. In addition, mowing treatments were started on plots at two timings (15 Mar. and 15 Apr.) to determine how mowing might affect survival and performance of the bulb species. Early performance was good for all bulb species and greater than 50% flower production was observed in the first spring (2011) after planting. However, in the subsequent 3 years (2012–14), the only species that persisted and continued to flower adequately each spring was ‘Ruby Giant’ crocus. Herbicides and mowing did not affect bulb survival or performance in the trial, suggesting that typical lawn management practices will not be deleterious to the bulbs. These results demonstrate that early spring bulbs may be incorporated into dormant, warm-season lawns, but species and cultivar selection will be crucial for long-term performance.
Filippo Lulli, Claudia de Bertoldi, Roberto Armeni, Lorenzo Guglielminetti and Marco Volterrani
Synthetic sports surfaces are increasingly subject to standardization of athlete-surface and ball-surface interactions (playability parameters). Such standardizations have led to an increase in the level of the engineering and predictability of these surfaces, and as such may be beneficial also for natural turf. In warm and temperate climates, many natural turf sports surfaces are established with warm-season (C4) turfgrass species due to their suitability to the environment in such areas. This study was aimed at evaluating the Féderation Internationale de Football Association (FIFA)-standard playing characteristics of different sports turf surfaces obtained from three commonly used C4 turfgrass species: 1) ‘Tifway 419’ hybrid bermudagrass (Cynodon dactylon var. dactylon × C. transvaalensis), 2) ‘Zeon’ manilagrass (Zoysia matrella), and 3) ‘Salam’ seashore paspalum (Paspalum vaginatum) for factors concerning leaf tissue (silica, lignin, water content) and canopy structure (shoot density, leaf architecture, stolon density, etc.). Results showed that surfaces of different C4 turfgrass species generate different playability parameters, with seashore paspalum being a harder faster surface, manilagrass being a softer slower surface, and hybrid bermudagrass showing intermediate characteristics. These playing quality results were associated with certain specific canopy biometrical/morphological parameters such as shoot density, horizontal stem density (HSD), leaf section, and, to a lesser extent, to certain plant tissue compounds (lignin, silica).
Marco Volterrani, Nicola Grossi, Monica Gaetani, Lisa Caturegli, Aimila-Eleni Nikolopoulou, Filippo Lulli and Simone Magni
Vegetatively propagated warm-season turfgrasses are established with methods that rely on large quantities of propagation material and subsequent plant growth support. The precision seeding adopted for some seed propagated crops controls the depth and spacing at which seeds are placed in the soil. Sprigs that are reduced in length could potentially be suitable for existing machinery, and precision planting could enhance the efficiency of use of the propagation material. The aim of the present study was to carry out a preliminary screening on products known to act as plant growth regulators to explore their potential use for controlling stolon development and elongation of ‘Patriot’ hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) grown in pots for propagation purposes. Trinexapac-ethyl (TE), chlormequat chloride (CM), paclobutrazol (PB), propiconazole (PPC), diquat (DQ), flazasulfuron (FS), glyphosate (GP), ethephon (EP), and gibberellic acid (GA) were applied to pot-grown ‘Patriot’ hybrid bermudagrass turf in eight different application rates, ranging for each product from the minimum expected effective rate to a potentially harmful rate. Of the tested treatments, TE applied at 2.0 kg·ha−1 and PB applied at 1.0 kg·ha−1 reduced stolon and internode length without causing a reduction in the stolon number or turf quality. PPC was also effective in reducing stolon length, but the effect on internode length was not statistically significant. Stolon length was unaffected by CM, while DQ and GP induced stolon elongation. FS, EP, and GA affected stolon length without a consistent relation between stolon length and application rate. The chemical suppression of stolon elongation in pot-grown ‘Patriot’ hybrid bermudagrass can contribute to controlling sprig size for use with precision seeding machinery.