Weed control in turf and lawns. Ralph Whitesides

Transcription

1 Weed control in turf and lawns Ralph Whitesides

2 Coarse- Leaved Tall Fescue: Good on roadsides Poor on better quality lawn Creeping Bentgrass: Serious problem on a lawn Great for golf greens Dandelion and Crabgrass considered weeds regardless of where they grow.

3 Broadleaves ruin uniformity of the turf, especially bad if flowers and seed heads appear. Some grass weeds also destroy uniformity Grow in clumps (orchardgrass) Poor color (barnyardgrass) Unsightly seed stalk (annual bluegrass) Different growth habit (crabgrass)

4 Weeds in Turf: Annual Grasses like Crabgrass Goosegrass Annual bluegrass Die each year and leave dead patches.

5 Weeds and turf compete for: Sunlight Nutrients Moisture Spread by: Seeds Rhizomes Stolons Bulbs and Tubers Bare spots are especially vulnerable to weeds

6 Weeds in turf: Best weed control in turf is PREVENTION, accomplished by intelligent establishment and maintenance. Weeds are a problem when turfgrasses lose density or do not achieve proper initial density. If grasses are adapted and maintained properly, then turf should be thick enough to out-compete weeds.

7 Practices to be re-evaluated: Fertilization Irrigation Mowing Disease control Insect control

8 Too wet Annual bluegrass Moss Sedges Solution: Reduce irrigation or improve drainage Too Dry: Goosegrass Birdsfoot trefoil Prostrate spurge Black medic Yellow woodsorrel (oxalis) Solution: Increase irrigation

9 Low Fertility Clovers Common speedwell Birdsfoot trefoil Hawkweed Solution: Apply more nitrogen Lack of Sun Ground ivy

10 Soil Compaction Annual bluegrass Broadleaf plantain Prostrate spurge Knotweed Goosegrass Common speedwell Solution: Core cultivation, aeration. Mowing Too Close (low growing weeds) Annual bluegrass Chickweed Some speedwells Moss Solution: Raise the cutting height.

11 Cutting Too High Burdock Teasel Bull thistle Solution: Partially controlled by lowering the cutting height.

12 Turfgrass species vary in herbicide tolerance and varieties vary within a species. Closely mowed more susceptible Plant stress reduces tolerance Cool season grasses more sensitive during hottest part of summer Warm season grasses sensitive during green-up but tolerant during dormant stage of winter.

13 Select the herbicide that has appropriate efficacy: 2,4-D: quite weak on knotweed, black medic dicamba: good on knotweed, black medic 2,4-D: noticeably weak on mallow bromoxynil: good on young mallow seedlings Perennial Weeds: Spot treat with glyphosate and respray in 7 days (allow for translocation) chlorsulfuron: Kills tall fescue, safe on Kentucky bluegrass and fine fescue

14 FMC Corporation Mixture of carfentrazone and quinclorac Registered in Utah for selective weed control in turf residential, commercial, institutional, athletic fields, commercial sod farms, golf course fairways and roughs, and other non-crop sites Check label for full details

15 Selective post-emergence herbicide Controls annual grasses and broadleaf weeds in established turf 70 WDG Better with good soil moisture No rainfall or irrigation within 24 hours However, needs 0.5 inch within 7 days

16 Tolerant grasses Annual bluegrass Kentucky bluegrass Fine fescue Tall fescue Perennial ryegrass

17 Weeds controlled or suppressed Barnyardgrass (c) Black medic (c) Clover (c) Crabgrass (c) Dandelion (c) Curly dock (s) Filaree (s) Foxtail (c) Plantain (c) Spurge (c) Star of Bethlehem (c)

18 DuPont Corporation Intended for Commerical Applicators Only 2 lb/gal liquid (potassium salt) Pre and/or postemergence selective control of broadleaves in turfgrass Use postemergence for perennial species Check label for full details

19 For use on established turfgrasses Recreational, home, business and office complexes, airports, day-care facilities, golf courses, athletic fields, and sod farms Tolerant grasses include Kentucky bluegrass Tall fescue Perennial ryegrass

20 Weeds controlled (only broadleaves) Black medic Clover Curly dock Canada thistle Chickweed Dandelion Plantain Purslane

21 Kill existing vegetation Good seedbed-new or old (reseeding) Don t expect grass to grow where nothing else will grow. Needs adequate: Water Sunshine ph balance

22 Plant clean seed/sod Read seed analysis Sanitize equipment from yard to yard Well adapted turf is less prone to weed invasion.