Transcript Weed Control

Weed Control
Weeds
A plant growing where it’s not wanted
 Weeds are opportunists
 Healthy, thick turf crowds out weeds
Life Cycles
Annuals: complete life cycle in one season
 Spread by seed
Life Cycles
Summer annual -- germinate in spring, die in
winter
 Leave dead spots for winter annuals to fill when
turf is not growing
Life Cycles
Winter annual -- germinate in winter, die in
summer
Life Cycles
Biennials: complete life cycle in 2 seasons
 First season is vegetative
 Second season is flowering
Life Cycles
Perennials: live 3 years or longer
 Mainly spread vegetative
– Rhizomes and tubers
Growth Habit
Broadleaf
 Normally have wide leaves
 Net-like veins on leaves
Growth Habit
Grasses
 Narrow, grass leaves
 Parallel veins on leaves
Growth Habit
Non-grass
 Sedge is triangular
 Rush is round
 Wild Garlic round
Weed Control
Selecting correct turf species
 Adapted species will out compete weeds
Weed Control
Cultural practices
Mowing: High mowing height
 Block light
Weed Control
Cultural practices
Mowing: Low mowing height
 Weaken turf
 Need more inputs for weed control
Weed Control
Herbicides

Mode of Action (MOA): how the
chemical is active within the plant to
control it
Herbicides
SELECTIVITY
 Selective: controls only certain plant
species without harming others
Herbicides
SELECTIVITY
 Nonselective: controls all plants it
contact
Herbicides
Contact: affects only
the green plant
material it contacts
 Often very rapid
control
 Not move within plant
– Not control spreading
parts, such as rhizomes
Herbicides
Systemic: translocated throughout the plant and parts
 Effective for underground parts
 Often slow control
Preemergent Herbicides

Control weeds prior to their emergence
– Kills weeds as they germinate

Will not control weeds once they emerge

Timing is critical
Preemergent Herbicides
Effective for 6 weeks (varies with product
and weather)
 Primary control of annual weeds

Preemergent Herbicides

Roots or shoots emerge and contact
herbicide
Preemergent Herbicides

Clean area before application
– Herbicide has to get to soil

0.25” to 0.5” water herbicide into soil
Preemergent Herbicides
Summer annuals
FEB 15 to MARCH 1
 Cherry and forsythia blooming
 Soil temperature >55 F
 Avoid weed and feed at this
time
– Too soon to fertilize
Weed and Feed
Combination of herbicide and fertilizer
 Can be pre- or post- emerge herbicide

– Most are pre
Post has to be applied to wet foliage
Preemergent Herbicides
Summer annuals: Second
application in May
 Weed and Feed is acceptable
 Second application not as
critical as first
Preemergent Herbicides
Winter annuals: October 1
 Night temps of 55 F to 60 F for several
days
 Not before overseeding
– 60 days or longer after overseeding
Preemergent Herbicides
Winter annuals: Second application in
December
 Helps control annual bluegrass
Preemergent Product Activity
Barricade, Team,
Surflan, Pre-M, and
Dimension
 Chemical absorbed
through shoots and
roots

Prevents cell division
Preemergent Product Activity
Barricade, Pre-M,
and Dimension
 Stolons will not
peg down
 Avoid use in thin
turf to spreading
Preemergent Product Activity
Ronstar
 Absorbed through shoots only
 Use to encourage spreading and
establishment
Preemergent Product Activity
Dimension
 Has some post and pre activity
 Usually control up to 4 leaf stage
 If application is late
Postemergent Herbicides
Control actively growing weeds
 Most effective on young, actively growing
weeds
 Avoid when turf is under stress

Postemergent Herbicides
Dicamba, 2,4-D, and MCPP (very common)
 Used in combinations to control broadleaf
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Turflon, Trimec, Weed-B-Gone
2,4-D good on dandelion
 MCPP good on clover
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Postemergent Herbicides
SpeedZone
4-way
 Carfentrazone added
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Postemergent Herbicides
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Vantage: controls bahia and bermuda in
centipede
Postemergent Herbicides
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Image, Monument, Sedgehammer: sedge
and annual bluegrass control