Upload
karma
View
38
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Effects of Postemergence Herbicides on Centipedegrass Seed Production. J. A. Ferrell, T. R. Murphy, W. K. Vencill University of Georgia. Centipedegrass popularity. Propagated via seed or sod Low maintenance Slow growth Low nitrogen requirement Herbicide tolerance - PowerPoint PPT Presentation
Citation preview
Effects of Postemergence Herbicides on Centipedegrass
Seed Production
J. A. Ferrell, T. R. Murphy, W. K. Vencill
University of Georgia
Centipedegrass popularity
• Propagated via seed or sod
• Low maintenance– Slow growth– Low nitrogen requirement
• Herbicide tolerance– Sethoxydim and clethodim– Halosulfuron
Changing Needs
Traditional Emphasis
• Color• Seedhead
Suppression• Weed Control
Production Emphasis
• Seed Yield• Seed Quality• Weed Control
Digitaria sanguinalis
Cyperus esculentus
Objectives
Determine the impact of herbicide and treatment timing on:
• Seedhead suppression• Seed yield• Seed quality
Herbicide Treatments
Herbicides• Clethodim • Sethoxydim• Halosulfuron
Spray Timing• -4 WPS*• -2 WPS • 0 WPS (Late July)• 2 WPS• 4 WPS
* Weeks post seedhead emergence
Materials and Methods
• Macon County, Georgia seed farm– Greenville clay loam
• Established centipedegrass (cv. ‘TifBlair’)
• Irrigated, weed-free site• Plot size – 6’ X 20’• 3 replications
Materials and Methods
• Clethodim – 0.25 lb ai A-1 + 0.25% v/v NIS• Sethoxydim – 0.28 lb ai A-1
• Halosulfuron – 0.062 lb ai A-1 + 0.5% v/v NIS• 25 GPA, flat fan nozzles, CO2 backpack• Seedhead suppression –0 to 100 scale• 3 x 5 factorial• Analysis: herbicide within treatment timing
Seedhead Suppression
Seedhead Suppression
Timing Clethodim Sethoxydim Halosulfuron
4 WBS NS NS NS
2 WBS NS NS NS
0 WBS NS
2 WPS NS
4 WPS NS NS NS
NS – non significant
Seedhead Suppression (0 WPS)
Herbicide 2 WAT 4 WAT
2001 2002 2001 2002%
Clethodim 50 12 31 0
Sethoxydim 21 3 3 3
Seedhead Suppression (2 WPS)
Herbicide 2 WAT 4 WAT
2001 2002 2001 2002%
Clethodim 33 16 23 5
Sethoxydim 18 0 13 0
Seed Yield
•October 10, 2001
•Harvested 2 randomly selected m2 quadrants
•Seeds removed from heads with mechanical thrasher
Seed Yield
20
40
60
80
100
120
-4 -2 0 2 4
Weeks Before Seeding
% o
f unt
reat
ed
ClethodimSethoxydimHalosulfuron
Seed Germination
• Conducted by Georgia State Seed Test Lab
• Conditions:– Covered petri dish with moist paper– Temperature – 20 to 35o C– Counts – 7 and 21 days
Seed Germination
70
80
90
100
110
-4 -2 0 2 4
Weeks Before Seeding
% o
f unt
reat
ed
ClethodimSethoxydimHalosulfuron
Conclusions
• Halosulfuron does not affect centipedegrass seed yield or germination
• Apply clethodim or sethoxydim as early as possible (minimum 4 WBS)
• Once seedheads emerge, use of clethodim or sethoxydim is not advisable
Future Centipedegrass Research
• Investigate effect of clethodim and sethoxydim in salvage situations (6, 8, 10 WPS)
• Effect of other commonly used herbicides on seed yield and quality
• Develop weed management systems in seedling centipedegrass
Acknowledgements
• Valent USA
• The Turfgrass Group
• Bill Nutt - technical assistance
www.bmen.tulane.edu/~mroberts
Any Questions?