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Basics of Turfgrass Weed Management: 

Basics of Turfgrass Weed Management Tim R. Murphy Crop and Soil Sciences The University of Georgia

What is a Weed?: 

What is a Weed? A plant out of place A plant whose virtues have yet to be discovered A flower in disguise

Is this plant a weed???: 

Is this plant a weed??? Common ragweed decreases crop yields, allergen Poison ivy skin rashes, fruit consumed by birds Tall fescue desirable turf and forage grass a weed in warm-season turfgrasses

Slide4: 

Human beings decide which plant is a WEED!!!!

Why are weeds an annual problem?: 

Why are weeds an annual problem? Seed and vegetative structure dormancy Prolific seed producers Spread of seed

Weed seed survival insured by:: 

Weed seed survival insured by: Hard seed coat (testa) Deep burial After ripening mechanisms Germination inhibitors

Slide8: 

Weeds are prolific seed producers. Seed/Plant Broadleaf plantain 36,000 Lambsquarters >30,000 Crabgrass 53,000 Texas Panicum 23,000 Annual Bluegrass 2,000

Slide9: 

Weeds - Nutsedge Spring 43,560 1 ft. Acre X 3,000,000 Plants 4,000,000 Tubers Fall Acre

Introduced weeds: 

Introduced weeds Johnsongrass Common lespedeza Crabgrass Broadleaf plantain Water-hyacinth

Factors affecting seed germination: 

Factors affecting seed germination Oxygen Light Scarification Temperature Water

Why control weeds?: 

Why control weeds?

Control vs. Eradication: 

Control vs. Eradication Control -Process of limiting a weed infestation to a level that is economically or aesthetically beneficial. Eradication -Elimination of all plants and plant parts of weed species from an area.

Weeds: 

Weeds Compete with desirable plants for sunlight, moisture and nutrients May exert allelopathic effects Reduce yields or quality of harvested product

Slide15: 

Why do we control weeds in turfgrasses?

Turfgrass Weeds: 

Turfgrass Weeds Reduce quality - leaf width, shape, color differences Reduce density - outcompete turfgrasses, can lead to erosion Decrease aesthetic value or utility of the turfgrass. - difficult to mow, disrupt uniformity of playing surfaces, safety considerations, attract insects

Develop A Plan: 

Develop A Plan Goals Methods Economics Alternatives Benefits

The Goal: 

The Goal Establish and maintain a high quality, nearly weed-free turfgrass.

Integrated Weed Management: 

Integrated Weed Management Methods Preventive Cultural Biological – not available in turfgrasses Mechanical Herbicides

Preventive Methods: 

Preventive Methods State and Federal laws Weed-free seed, sod, sprigs Weed-free topsoil, topdressing Clean equipment Field borders

Cultural Methods: 

Cultural Methods Adapted turfgrasses Fertility Cultivation Water management Insect and disease control

Southeast U. S. Turfgrasses: 

Southeast U. S. Turfgrasses

Soil Fertility Effects on Weeds: 

Soil Fertility Effects on Weeds Low N - legumes, mosses, speedwell High P - annual bluegrass High N - common chickweed, ryegrass, annual bluegrass Low soil pH - red sorrel, broomsedge

Weeds Favored by High Soil Moisture: 

Weeds Favored by High Soil Moisture Sedges - purple nutsedge, green kyllinga Rushes Annual bluegrass Mosses, algae Alligatorweed Pennywort

Weeds Favored by Low Soil Moisture: 

Weeds Favored by Low Soil Moisture Prostrate spurge Poorjoe Common lespedeza Prostrate knotweed

Weeds Favored in Compacted Soils: 

Weeds Favored in Compacted Soils Annual bluegrass Goosegrass Prostrate knotweed Common lespedeza Path rush

Weeds may indicate a nematode problem: 

Weeds may indicate a nematode problem spurges Florida pusley prostrate knotweed

Mechanical Methods: 

Mechanical Methods Mowing Hand removal

Why does mowing control tall-growing weeds?: 

Why does mowing control tall-growing weeds? Reduces apical dominance of main stem Basal buds initiate growth Continued clipping depletes root carbohydrates Prevents weed seed formation

Why does mowing not control low-growing weeds?: 

Why does mowing not control low-growing weeds? Primary growing point is located beneath the mower blade.

Slide39: 

Kentucky Bluegrass

Herbicides: 

Herbicides Herbicide – a chemical used to control, suppress or kill plants. Preemergence – applied before weed seeds germinate Postemergence – applied to emerged weeds

Herbicides: 

Herbicides Turf species vary in tolerance Weed species vary in susceptibility Turfgrass species and weed identification is critical to herbicide selection!!!!

Maintain Healthy Turfgrass: 

Maintain Healthy Turfgrass Manage the roots to have good shoots Soil testing is a must! Utilize cultural practices (fertility, irrigation, mowing height, etc.) to improve stress tolerance Keep mower blades sharp ! Use the best species and cultivars for your location

Identify the Weed Problem: 

Identify the Weed Problem READ textbooks and periodicals Keep a diagnostic tool kit - hand lens, etc. Know the life cycle of the pest (What temp. does a specific weed seed germinate?) Is the weed the cause or effect of the problem? Confirm your diagnosis

Weed Thresholds - ??: 

Weed Thresholds - ?? Site - putting green, lawn, etc. People - expectations Weed - population dynamics Budget - dollars

Scouting Sites: 

Scouting Sites Use zig-zag pattern Make random stops

Scouting Sites: 

Scouting Sites Identify weeds and life cycle Record observations by area - ornamental beds - turfgrass areas * front lawn * back lawn

Scouting Sites: 

Scouting Sites Record density by species Low - 1 to 10% Medium - 11 to 20% High - > 20%

When to Scout?: 

When to Scout? Mid-winter months - winter weeds Late-April to July - summer weeds Late summer - assess summer program Late spring - assess winter program

Developing a Weed Management Program: 

Developing a Weed Management Program Prevent weed introduction Properly maintain turfgrasses Identify weeds and learn life cycle Initiate control practices Preventive Cultural Mechanical Herbicides