Full TGIF Record # 225767
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Publication Type:
i
Report
Author(s):Gover, Arthur E.; Watschke, Thomas L.; Lyman, Gregory T.
Author Affiliation:Gover: Project Associate; Lyman: Former Project Assistant, Agronomy; Watschke: Professor, Turfgrass Science
Title:The effect of application timing on the activity of plant growth regulators applied to tall fescue
Section:1990 results: Roadside vegetation management studies
Other records with the "1990 results: Roadside vegetation management studies" Section
Source:Turfgrass Research Results 1990/1991 [Penn State]. 1991, p. 58-60.
# of Pages:3
Publishing Information:[University Park, Pennsylvania]: [Pennsylvania State University, College of Agriculture, Agronomy Dept., Entomology Dept., Horticulture Dept., Plant Pathology Dept.]
Abstract/Contents:"Previous research has suggested that different plant growth regulators (PGR's) have different periods of peak activity between the breaking of dormancy and seedhead emergence on unmown tall fescue (Festuca arundinacea). This study was initiated as part of a cooperative research project with the Pennsylvania Department of Transportation to determine if different plant growth regulator combinations demonstrated different activity peaks within the pre-mow application window. The study site was seeded in the spring of 1987 to a blend of 'Cimmaron', 'Bonanza', and 'Olympic' turf type fall fescues. Prior to 1990, the area received 54 lb/acre of N annually, and was maintained at a height of 3.5 in. The experimental design was randomized complete block with a split-plot treatment arrangement with three replications. Each 18 by 15 ft application timing whole plot was divided into six 3 by 15 PGR treatment sub-plots. The application times were April 23, April 27, May 2, May 8, and May 14, 1990. The PGR treatments were mefluidide, chlorsulfuron, meluidide plus chlorsulfuron, a commercial premix of imazethapyr and imazapyr, mefluidide plus imazethapyr and imazapyr, and an untreated check. The treatments were applied with a CO2 powered hand held sprayer delivering 17 GPA at 30 psi using Spraying Systems 8002 flat fan nozzles. All PGR treatments included dicamba at 0.5 lb ae/acre and a non-ionic spray adjuvant at 0.25% (v/v). Initial visual ratings of turf color and turf quality were taken May 15 for the April 23 applications; May 29 for the April 27, May 2, and May 8 applications; and June 5 for the May 14 application. All plots were visually rated for percent seedhead suppression, turf color, and turf quality on July 2. Seedhead suppression ratings were based on the untreated check within each application time whole plot. Turf color and quality were rated on a 0 to 9 scale, with '9' being ideal, '0' dead turf, and '5' acceptable. When the data was subjected to analysis of variance, the interaction between application time and PGR treatments was highly significant for all dependent variables. The untreated check received the highest initial turf color ratings for each application date. The initial turf quality rating fell dramatically to unacceptable levels after the April 23 application due to the uneven appearance resulting from unchecked growth. Seedhead pressure was different between the check plots, but was always rated 0 percent suppression. July 2 ratings of turf color were barely acceptable as leaf senescence was occurring, and turf quality was unacceptable due to the presence of seedheads and uneven canopy growth. Initial color ratings for mefluidide alone were acceptable and consistent for all applications. Turf quality ratings decreased for later applications as the turf grew taller with a more uneven canopy compared to other treatments. Seedhead suppression ratings taken July 2 were good to excellent for applications made April 23 and 27, then decreased significantly for the May 2 application. Turf color and quality ratings taken July 2 followed the same trend as the seedhead suppression ratings. The color decline appeared to be due to the beginning of leaf senescence, an the quality decline was due to increasing presence of seedheads and an uneven canopy, and less favorable color ratings. Chlorsulfuron showed an improved initial color rating between the April 23 and 27 application dates, then no change with subsequent applications. The initial quality ratings were more varied, though acceptable, and did not show any overall trend. Seedhead suppression was not acceptable for the April 23 and 27, and May 2 applications, but improved to acceptable levels for the May 8 and 14 applications. When rated July 2, turf color and quality were consistent and acceptable for all application dates. The combination of mefluidide and chlorsulfuron, produced barely acceptable initial color ratings for the April 23 and 27 applications. Turf color ratings improved with the later applications, but this combination consistently received the lowest initial turf color ratings. Initial turf quality relative to the other treatments changed from worst rated for April 23 to best rated for May 14, despite a change of only 6.3 to 7.0. July 2 ratings of seedhead suppression, turf color, and turf quality were good to excellent for all application dates. The commercial premix of imazethapyr and imazapyr showed initial turf color and turf quality ratings between 6.3 and 7.0 for all application dates. Seedhead suppression was good to excellent for all application dates, as was turf color and turf quality when rated July 2. Adding mefluidide to the premix of imazethapyr and imazapyr produced initial turf color ratings that were consistently lower, though acceptable, than the premix alone. Initial turf quality differences between the two treatments were not apparent. Mefluidide plus the premix consistently provided excellent seedhead suppression, and was among the highest for July 2 turf color and quality ratings. Under the conditions of this study, mefluidide showed greater activity on tall fescue in earlier applications. When combined with a reduced rate of chlorsulfuron, early applications caused more discoloration, but seedhead suppression was improved. Similar results were found when mefluidide was combined with a commercial premix of imazethapyr and imazapyr, though improvements in seedhead suppression were not as pronounced as with chlorsulfuron."
Language:English
References:0
Note:This item is an abstract and table only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Gover, A. E., T. L. Watschke, and G. T. Lyman. 1991. The effect of application timing on the activity of plant growth regulators applied to tall fescue. Turfgrass Research Results 1990/1991 [Penn State]. p. 58-60.
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