Weed Management Weed Management on Putting Greenson Putting Greens

Dr. Tim R. Murphy

Extension Weed Specialist

University of Georgia

Griffin

Problem Putting Green Weeds

• Annual Bluegrass - annual and perennial

• Goosegrass

• Crabgrass

• occasional broadleaf weeds

• nutsedge(s)

Bermudagrass Greens

• Preemergence crabgrass and goosegrass

– Bensulide (Bensumec, Pre-San, Betasan– Dithiopyr (Dimension)– Bensulide + oxadiazon (Scotts Goosegrass/Crabgrass

Control)

Bermudagrass Greens

• Postemergence crabgrass and goosegrass

– Diclofop (Illoxan), goosegrass only– MSMA/DSMA - low rates, repeat applications, very

risky, avoid air temperatures > 85 F.

Bermudagrass Greens

• Preemergence annual bluegrass control– Pronamide (Kerb) , apply 60 to 90 days before

overseeding, activated charcoal is used when applications made < 90 days before overseeding

– Fenarimol (Rubigan), apply 2 to 3 applications, last application 14 days before overseeding perennial ryegrass (30 days on P. trivialis), apply low rate in Jan.-Feb, for extended control

Creeping Bentgrass Greens

• Preemergence crabgrass and goosegrass

– Bensulide (Bensumec, Pre-San, Betasan– Dithiopyr (Dimension)– Bensulide + oxadiazon (Scotts Goosegrass/Crabgrass

Control)

Creeping Bentgrass Greens

• Postemergence crabgrass and goosegrass

– No herbicides labeled for this use– Low tolerance of creeping bentgrass– MSMA/DSMA - very risky– Acclaim Extra - too injurious

Creeping Bentgrass Greens

• Annual bluegrass control

• Paclobutrazol (Scotts TGR, Trimmit)• a plant growth regulator that inhibits gibberellin

biosynthesis

• Poa more sensitive than bentgrass

• apply in spring after bentgrass growth has resumed

• works slowly, repeat applications needed

• fall + spring applications needed for P. annua var. reptans

Perennial Poa Treatments (Johnson and Murphy, 1995)

• TGR applied Oct. 1 + Nov 12 fb Mar 15 + May 1 for 2 yr suppressed Poa 28% 4 MAT

• TGR at 0.5 + 0.25 fb 0.5 + 0.25 lbs. Ai/acre

• Cutless at same dates and rates suppressed Poa 6% 4 MAT

Perennial Poa Treatments (Johnson and Murphy, 1996)

Date TGR Cutless

mid-Mar 0.5 0.5

mid-Apr 0.5 0.5

mid-May 0.25 0.25

Oct 1 0.38 0.38

Nov 1 0.38 0.38

Dec 1 0.25 0.25

Perennial Poa Suppression

0

10

20

30

40

50

60

70

80

% S

uppr

essi

on

1 21 82 103

DALT

TGR Cutless

Maximum Bentgrass Injury

0 5 10 15 20 25 30

Mar - 12d

Apr - 9d

May - 7d

Oct - 13d

Nov - 11d

Dec - 6d

% Injury

TGR