Effects of Growth Retardants on the Shoot and Root Growth of Roadside Turfgrasses1
- R. C. Wakefield and
- S. L. Fales
Growth retardants were evaluated to determine their effects on shoot and root growth of several turfgrass species under roadside cultural conditions. Growth suppression and phytotoxicity were measured on a typical roadside turfgrass polystand consisting of red fescue (Festuca rubra L.), Kentucky bluegrass (Poa pratensis L.), and colonial bentgrass (Agrostis tenuis Sibth.) and on monostands of Kentucky bluegrass, red fescue, and tall fescue (Festuca arundinacea Shreb.). An index of root growth was obtained from treated turfgrass plugs, which were embedded in sand and sampled at 3, 5, 7, and 9 weeks for new growth.
Two growth retardants, fluoridimide (N-[4-methyl-3-[[(1, 1, 1-trifluoromethyl) sulfonyl]amino]phynyl]acetamide) and mefluidide (N-[2, 4-dimethyl-5-]](trifluoromethyl) sulfonyl]amino]phenyl]acetamide) were compared to the standards maleic hydrazide (1, 2-dyhydro-3, 6-pyridazinedione) and a mixture of maleic hydrazide and chlorflurenol (methyl-2-chloro-9-hydroxyfluorene-9-carboxylate, 8.8 %; methyl-9-hydroxy-fluorene-9-carboxylate, 2.1 %; methyl-2,7-dichloro-9-carboxylate, 1.6 %). All growth retardants significantly reduced both vegetative and seedhead growth with mefluidide being particularly effective at rates as low as 0.42 kg/ha. Discoloration and loss of shoot density occurred with all growth retardants but was not objectionable with any treatments.
Root growth, as measured by root weights from treated turfgrass plugs, was initially reduced by all growth retardants. Reduction in root growth with mefluidide was far less severe, recovery was rapid, and some stimulation of root growth was then measured. Rhizome growth of Kentucky bluegrass was also affected far less with mefluidide than with the other growth retardants.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1980. . Copyright © 1980 by the American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, and International Turfgrass Society, 5585 Guilford Rd., Madison, WI 53711 USA