Full TGIF Record # 30506
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Publication Type:
i
Report
Content Type:Abstract or Summary only
Author(s):Doney, J. C. Jr.; Vincelli, P. C.; Powell, A. J. Jr.
Author Affiliation:Department of Plant Pathology; Department of Agronomy, University of Kentucky
Title:Reactions of bentgrasses to dollar spot and brown patch, 1992
Source:Biological and Cultural Tests for Control of Plant. Vol. 8, 1993, p. 118.
Publishing Information:St. Paul, MN: The American Phytopathological Society
# of Pages:1
Keywords:TIC Keywords: Agrostis tenuis; Agrostis stolonifera; Agrostis castellana; Dollar spot; Brown patch
Abstract/Contents:"Twenty cultivars of four species of bentgrass (Agrostis spp.) were established in Maury silt loam on 21 Sep 89 as part of the National Bentgrass Fairways and Tees Evaluation. Three replicated plots (8 X 12 ft) of each variety were arranged in a RCB design. Two fall applications of urea (60 lb Nitrogen/A at each application) were made in 1991. Plots were maintained at a height of 0.5 inches and were not irrigated during the evaluation period. Weather conditions at the University of Kentucky Spindletop Research Farm consisted of a warm (25C), wet (7.5 cm above average) spring followed by a cool summer. Bentgrass susceptibility to each disease was evaluated using three randomly located one square foot quadrats in each plot. In each quadrat Dollar Spot (DS) infection centers were counted on 23 Jun and 2 Jul, the percentage of remaining turf with Brown Patch (BP) was estimated on 2 Jul. BP was estimated similarily on 15 Jun. The disease levels in the three quadrats were averaged to obtain a mean disease estimate for each plot. Number of DS infection centers and arc sine transformed values for percent BP on each date were evaluated for varietal differences using ANOVA and Waller-Duncan K-ratio mean separation test at P = 0.05. An individual variety in the highest mean separation ranking in each evaluation for particular disease was considered resistant. Significant increase or decrease in experiment wide disease levels between dates of evaluation was tested for using Students t-test at P = 0.10. Change in disease levels between evaluation dates for individual varieties was tested for using Students t-test at P = 0.10. Environmental conditions of varying favorability for disease development occurred in Jun and Jul. This allowed for evaluation of varietal differences of resistance to DS and BP under varying levels of disease pressure. There were significant differences in the number of DS infection centers and the percent BP at each evaluation. At no time during evaluation were environmental conditions highly conducive for a BP epidemic to develop. Mean percent BP for individual varieties ranged from 6 to 53% and 0.3 to 23% on 15 Jun and 2 Jul, respectively. The mean BP disease level across all varieties in the experiment decreased (P = 0.10) from 15 Jun (30%) to 2 Jul (4%). Percent BP decreased (P = 0.10) from 15 Jun to 2 Jul in 19 varieties. Percent BP in the resistant variety Penncross on 15 Jun was only 6.5%, possibly making any significant reduction difficult to detect. Mean number of DS infection centers per square foot for individual varieties ranged from 1 to 160 on 23 Jun, and 3 to 282 on 2 Jul. Mean number of DS infection centers across all varieties in the experiment increased (P = 0.10) from 28 per square foot on 23 Jun to 81 per square foot on 2 Jul. Number of DS infection centers increased from 23 Jun to 2 Jul (P = 0.10) in nine varieties (88 CBL, Penneagle, Regent, Bardot, Cobra, TAMU 881, Penncross, SR 1020, and Emerald). Resistance to DS was displayed by 14 varieties in this evaluation. Resistance to BP was exhibited by the varieties 88 CBE and WVPB 89D15. Comparatively high levels of resistance to either DS or BP were observed in individual varieties, but no variety clearly displayed a level of resistance to either disease adequate to eliminate chemical control. Chemical applications would have been needed in order to maintain DS disease suppression, in the susceptible and least resistant varieties, at levels similar to those in BR 1518 or 88 CBL. A similar statement can be made regarding BP levels in the varieties Egmont and Allure compared to Penncross and 88 CBE. A. tenuis, A. capillaris and A. castellana are not adequately represented in this study but appear to be less susceptible to DS and more susceptible to BP than A. palustris. Further research will be needed to show if disease resistance can be integrated with chemical control strategies to minimize fungicide use for fairways and tees."
Language:English
References:0
See Also:Other items relating to: DOLLAR
Note:Table
This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Doney, J. C. Jr., P. C. Vincelli, and A. J. Jr. Powell. 1993. Reactions of bentgrasses to dollar spot and brown patch, 1992. Biol. Cult. Tests Control Plant Dis. 8:p. 118.
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