Spring and Fall Preemergence Weed Control Options for Turf Dr. Tim R. Murphy Extension Weed...
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Transcript of Spring and Fall Preemergence Weed Control Options for Turf Dr. Tim R. Murphy Extension Weed...
Spring and Fall Preemergence Spring and Fall Preemergence Weed Control Options for TurfWeed Control Options for Turf
Dr. Tim R. Murphy
Extension Weed Specialist
University of Georgia
Griffin
Preemergence Options
Atrazine PendimethalinSimazine KerbBalan DimensionXL BensulideTeamPro PennantSurflan GalleryBarricade Devrinol
Repeat Applications - Summer
• Space 8 to 10 wks apart
• Apply 1/2 X fb 1/2X
• May improve control of crabgrass and goosegrass
Goosegrass
• Summer annual
• Germinates - soil temp. 4 inch depth averages 60 to 65 F.
• Usually germinates 2 to 6 weeks later than crabgrass
• Light required
Crabgrass spp.
• Summer annual
• At least 5 species in GA (tropical, smooth, large, southern, blanket)
• Germinates at soil temps. - 53 to 58 F., 4 inch depth
• Light required
Annual bluegrass
• Winter annual
• Germinates late summer-fall at soil temperatures around 70 F.
• Second germination flush in mid- to late-winter
Continuous annual bluegrass seedgermination occurred from mid-Nov.through early January in Knoxville, TN.
Callahan and McDonald, 1992
Preemergence Herbicides
• Need rainfall or irrigation (1/2 inch)
• Do not control emerged weeds
• Granular or sprayable
• Most available on dry fertilizer carriers
Guidelines - Preemergence
• Labeled products only
• Established turfgrass
• Apply before weed emergence
• Need rainfall or irrigation within 5 days
• Consider split applications
• Delay mowing until after incorporation
• Know future plans
Fertilizer/Preemergence Products
• Correct fertilizer analysis??
• Time of year??
• N-release characteristics??
• Supplemental fertilizer applications??
• Supplemental herbicide applications??
Fertilizer/Preemergence Products - Other Considerations
• Uniform coverage required
• Uniform particle size is important
• Release characteristics of fertilizer product
• Control equivalent to sprayable and granular products
Preemergence Herbicides - Formulation Effects
Barricade lbs. ai/acreSmooth Crabgrass
Control (%)65WG 0.75 98
0.29G 0.75 91
0.5G 0.75 81
Yelverton, et al., 1996
Preemergence Herbicides- Formulation Effects
% Control
Dimension lbs. ai/acreSmooth
Crabgrass Goosegrass1EC 0.5 64 31
1EC 0.75 91 29
0.25G 0.25 82 55
0.25G 0.38 100 78
0.25G 0.5 100 82
Johnson and Murphy, 1991
Preemergence Herbicides- Formulation Effects
% Control
Dimension lbs. ai/acreLarge
Crabgrass Goosegrass1EC 0.25 + 0.25 88 72
18-3-12G 0.25 + 0.25 96 94
Johnson and Murphy, 1991
Weed Life Cycles
• Summer annuals - < 1 yr.
• Winter annuals - <1 yr.
• Biennials - 2 yr.
• Perennials - > 2 yr.
Preemergence Herbicide Selection
• Turfgrass species
• Weed species
• Immature vs. established
• Time of year
• Irrigation capabilities
• Renovation plans
Preemergence Herbicide Selection
• Granular or spray equipment
• Desired control level
• Application frequency
• Ornamental tolerance
• Cost??
Suggested Application Dates
• North Georgia– Spring, March 1 - 20– Fall, August 20 - Sept. 15
• South Georgia– Spring, Feb. 10 - March 1– Fall, Sept. 20 - Oct. 15
• Early is always better than late!