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Annual Bluegrass

Description

Annual bluegrass is a light green bunch-type to slightly spreading winter annual weedy grass. Some subspecies exist which are classified as short-lived perennials (Poa annua ssp. reptans). These perennial types are particularly evident in bentgrass golf greens. One reason annual bluegrass is so unsightly is its ability to produce a light colored seedhead even at very low mowing heights.

Cultural Control

Management practices that encourage annual bluegrass persistence include: 1) excessively close mowing; 2) shallow, frequent irrigation; 3) poor soil drainage; 4) improperly timed fertilization; 5) aerifying or dethatching during primary periods of germination; 6) use of heavy equipment causing compaction; and 7) shade.

Chemical Control

Herbicide and Formulation
Amount of Formulation per 1,000 sq ft
Amount of Formulation per Acre
Pounds Active Ingredient per Acre

Preemergence Control

Herbicide and Formulation

benefin + trifluralin, MOA 3 + 3 (0.86 G)

Amount of Formulation per 1,000 sq ft

4 to 8 lb

Amount of Formulation per Acre

174 to 349 lb

Pounds Active Ingredient per Acre

1.5 to 3

Precaution and Remarks

Apply during late summer before Poa annua germinates. Do not apply to turf areas that are to be overseeded. See section on preemergence control of crabgrass and goosegrass or product labels for turfgrass tolerance, precautions and remarks for the listed preemergence annual bluegrass herbicides.

Preemergence Control

Herbicide and Formulation

bensulide, MOA 8 (4 EC) (8.5 G, 12.5 G)

Amount of Formulation per 1,000 sq ft

Amount of Formulation per Acre

several concentrations available

Pounds Active Ingredient per Acre

12.5

Precaution and Remarks

Apply during late summer before Poa annua germinates. Do not apply to turf areas that are to be overseeded. See section on preemergence control of crabgrass and goosegrass or product labels for turfgrass tolerance, precautions and remarks for the listed preemergence annual bluegrass herbicides.

Preemergence Control

Herbicide and Formulation

dithiopyr, MOA 4 (2 EW, 2 L) (40 WP)

Amount of Formulation per 1,000 sq ft

0.75 fl oz 0.46 oz

Amount of Formulation per Acre

1 qt 20 oz

Pounds Active Ingredient per Acre

0.5

Precaution and Remarks

Timely irrigation or rainfall is critical for activation.

Preemergence Control

Herbicide and Formulation

indaziflam, MOA 21 (20 WSP) (0.622 F) (0.0224 G)

Amount of Formulation per 1,000 sq ft

0.057 to 0.115 oz 0.138 to 0.23 fl oz 2.9 to 4.6 lb

Amount of Formulation per Acre

2.5 to 5 oz 6 to 10 fl oz 125 to 200 lb

Pounds Active Ingredient per Acre

0.031 to 0.063 0.029 to 0.049 0.028 to 0.045

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

metolachlor, MOA 15 (7.62 EC)

Amount of Formulation per 1,000 sq ft

0.48 to 0.96 fl oz

Amount of Formulation per Acre

1.3 to 2.6 pt

Pounds Active Ingredient per Acre

t 1.24 to 2.48

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

napropamide, MOA 15 (50 DF)

Amount of Formulation per 1,000 sq ft

1.5 to 2.25 oz

Amount of Formulation per Acre

4 to 6 lb

Pounds Active Ingredient per Acre

2 to 3

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

oryzalin, MOA 3 (4 AS) (85 WDG)

Amount of Formulation per 1,000 sq ft

1.1 fl oz 0.64 to 0.88 oz

Amount of Formulation per Acre

1.5 qt 1.75 to 2.4 lb

Pounds Active Ingredient per Acre

1.5 1.4875 to 2.04

Precaution and Remarks

Apply full rate unless potentially thin turfgrass cover is a problem caused by dense poa infestation.

Preemergence Control

Herbicide and Formulation

oxadiazon, MOA 14 (2 G)

Amount of Formulation per 1,000 sq ft

2.3 to 4.6 lb

Amount of Formulation per Acre

100 to 200 lb

Pounds Active Ingredient per Acre

2 to 4

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

pendimethalin, MOA 3 (2 G) (0.86 G) (1.29 G) (3.8 CS)

Amount of Formulation per 1,000 sq ft

1.72 to 3.44 lb 2.67 to 5.34 lb 2.67 lb 1.15 to 1.55 fl oz

Amount of Formulation per Acre

75 to 150 lb 116 to 232 lb 116 lb 3.1 to 4.2 pt

Pounds Active Ingredient per Acre

1.5 to 3 1 to 2 1.5 1.5 to 2

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

pendimethalin + dimethemamid, MOA 3 + 15 (1.75 G)

Amount of Formulation per 1,000 sq ft

2.3 to 4.6 lb

Amount of Formulation per Acre

100 to 200

Pounds Active Ingredient per Acre

1.75 to 3.5

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

prodiamine, MOA 3 (65 WG) (4 FL)

Amount of Formulation per 1,000 sq ft

0.185 to 0.83 oz 0.23 to 1.1 fl oz

Amount of Formulation per Acre

0.5 to 2.3 lb 0.625 to 3 pt

Pounds Active Ingredient per Acre

0.325 to 1.5 0.3125 to 1.5

Precaution and Remarks

Preemergence Control

Herbicide and Formulation

pronamide, MOA 3 (3.3 SC)

Amount of Formulation per 1,000 sq ft

0.46 to 1.29 fl oz

Amount of Formulation per Acre

1.25 to 3.5 pt

Pounds Active Ingredient per Acre

0.5 to 1.5

Precaution and Remarks

Not for home use. Can be applied from Sept. 15 to Feb. 1 for preemergence or postemergence annual bluegrass control in bermudagrass, zoysiagrass, centipedegrass, and St. Augustinegrass grown for sod, nonresidential or industrial sites, golf course turf, and stadium or professional athletic fields. 1.25 to 2.5 pints per acre provides preemergence to pre tiller stage control. 2 to 2.5 pints per acre provides postemergence control from early tiller to early seedhead stage. 2.5 to 3.5 pints per acre needed for postemergence control at seedhead stage. Henbit and chickweed species controlled at preemergence timings. Can be used for removal of overseeded grasses; therefore, do not overseed if it is desired to maintain a stand. Do not overseed treated area within 90 days of treatment. Injury symptoms from postemergence applications can take up to 5 weeks to develop.

Preemergence Control

Herbicide and Formulation

benefin, MOA 3 (2.5 G)

Amount of Formulation per 1,000 sq ft

2.75 lb

Amount of Formulation per Acre

120 lb

Pounds Active Ingredient per Acre

3

Precaution and Remarks

Apply in late summer before Poa annua germinates. Perennial ryegrass can be overseeded 6 weeks after benefin is applied.

Preemergence Control

Herbicide and Formulation

dithiopyr, MOA 4 (2 EW, 2 L) (40 WP)

Amount of Formulation per 1,000 sq ft

0.75 fl oz 0.46 oz

Amount of Formulation per Acre

1 qt 20 oz

Pounds Active Ingredient per Acre

0.5

Precaution and Remarks

Apply in late summer before Poa annua germinates. Perennial ryegrass can be overseeded 6 to 8 weeks after application. Apply only on well-established bermudagrass. Do not reapply in fall or winter after overseeding unless injury can be tolerated.

Preemergence Control

Herbicide and Formulation

prodiamine, MOA 3 (65 WG)

Amount of Formulation per 1,000 sq ft

0.213 to 0.367 oz

Amount of Formulation per Acre

0.58 to 1 lb

Pounds Active Ingredient per Acre

0.37 to 0.65

Precaution and Remarks

Use on golf courses (excluding putting greens) when overseeding with perennial ryegrass at a minimum seeding rate of 350 pounds per acre. Apply 8 to 10 weeks before overseeding and expect 70% or greater control. For best potential control, use higher rate and shorter time interval before overseeding. However, this could increase ryegrass seedling mortality or temporarily reduce root growth.

Preemergence Control

Herbicide and Formulation

ethofumesate, MOA 8 (1.5 EC)

Amount of Formulation per 1,000 sq ft

2 fl oz

Amount of Formulation per Acre

2.67 qt

Pounds Active Ingredient per Acre

1

Precaution and Remarks

For control of annual bluegrass in dormant bermudagrass overseeded with perennial ryegrass or in established perennial ryegrass turf. Rates are per application. The first application should be 30 to 45 days after overseeding with perennial ryegrass. The second application should be 21 to 28 days later. Do not apply ethofumesate to overseeded bermudagrass after Jan. 1 in N.C.

Preemergence Control

Herbicide and Formulation

ethofumesate, MOA 8 (4 SC)

Amount of Formulation per 1,000 sq ft

0.55 to 1.47 fl oz

Amount of Formulation per Acre

1.5 to 4 pt

Pounds Active Ingredient per Acre

0.75 to 2

Precaution and Remarks

Must be professionally applied to residential and nonresidential turf including golf courses and sod farms. May be applied to established perennial ryegrass, Kentucky bluegrass, creeping bentgrass, tall fescue, St. Augustinegrass, and dormant bermudagrass. Do not apply to putting greens. Delay application at least 8 weeks after a pgr application. Fall annual bluegrass control best during period of maximum germination. Spring appliclations most effective following fall applications. For overseeded bermudagrass, apply 1 to 2 weeks after perennial ryegrass emergence and repeat at 21- to 28-day intervals. Do not apply to bermudagrass 4 weeks prior to breaking winter dormancy.

Postemergence Control and Seedhead Suppression

Herbicide and Formulation

bispyribac-sodium, MOA 2 (17.6 SG)

Amount of Formulation per 1,000 sq ft

0.046 to 0.138 oz

Amount of Formulation per Acre

2 to 6 oz

Pounds Active Ingredient per Acre

0.021875 to 0.065625

Precaution and Remarks

Do not apply to putting greens, ryegrass mowed to less than 0.375 inch, or nonoverseeded bermudagrass. Apply between Feb. 1 and March 15. Make first application when annual bluegrass begins flowering. If actively flowering, use the low rate and re-treat in 28 to 35 days. If not actively flowering, use the low rate and retreat in 14 to 21 days with the low rate. Do not apply if air temperature is less than 50 degrees F within 3 days after application. Check label for further special instructions.

Postemergence Control and Seedhead Suppression

Herbicide and Formulation

amicarbazone, MOA 5 (70 WG)

Amount of Formulation per 1,000 sq ft

0.023 to 0.23 oz

Amount of Formulation per Acre

1 to 10 oz

Pounds Active Ingredient per Acre

0.044 to 0.44

Precaution and Remarks

Also tolerant to 6 months established turfgrasses such as bahiagrass, centipedegrass, seashore paspalum, St. Augustinegrass, zoysiagrass, bentgrass, Kentucky bluegrass, perennial ryegrass, fine and tall fescue. Labeled for use on golf course, sod farm, residential, commercial, athletic field and roadside turf. Bentgrass tees: 1 ounce per acre at 7 day intervals for 4 applications. Bentgrass roughs and fairways: 2 to 3 ounces/acre for 14 to 21 day intervals for 2 applications. Cool season turf: 2 to 4 ounces per acre for 14 to 21 day intervals for 2 applications. Warm season turf: 3 to 10 ounces per acre for 14 to 21 day intervals for 2 applications not to exceed 10 ounces per acre per year. Allow 4 weeks before cutting or lifting sod. Allow 1 week before overseeding winter grasses.

Postemergence Control

Herbicide and Formulation

flazasulfuron, MOA 2 (25 DG)

Amount of Formulation per 1,000 sq ft

0.011 to 0.069 oz

Amount of Formulation per Acre

0.5 to 3 oz

Pounds Active Ingredient per Acre

0.0078 to 0.0469

Precaution and Remarks

For use on well established bermudagrass, zoysiagrass, centipedegrass and seashore paspalum grown on nonresidential turf including golf courses, industrial parks, tank-sod- and seed farms, cemeteries, athletic field and commercial lawns. Apply a maximum of 1.5 ounces per acre on fully green centipedegrass and seashore paspalum. 3 ounces per acre needed for annual bluegrass control and best if applied in spring. 0.5 to 1.5 ounces per acre will control perennial and Italian ryegrass. For clumpy ryegrass, use 1.5 to 3 ounces per acre. 1.5 ounces per acre needed for tall fescue control. 2.25 to 3 ounces per acre needed for poa trivialis control. Include a nonionic surfactant at 0.25% by volume

Postemergence Control

Herbicide and Formulation

foramsulfuron, MOA 2 (0.19 SC)

Amount of Formulation per 1,000 sq ft

0.2 to 0.6 fl oz

Amount of Formulation per Acre

8.8 to 26.2 fl oz

Pounds Active Ingredient per Acre

0.013 to 0.039

Precaution and Remarks

For use on bermudagrass and zoysiagrass grown on home lawns, golf courses and sod farms. Do not use on warm season turfgrass collars surrounding bentgrass greens. May be applied up to 1 week prior to overseeding. Do not apply within 2 weeks of bermudagrass sprigging. Apply in 25 to 60 gallons water per acre. Rainfast after 2 hours. Surfactant not required.

Preemergence Control

Herbicide and Formulation

rimsulfuron, MOA 2 (25 DF)

Amount of Formulation per 1,000 sq ft

0.011 to 0.092 oz

Amount of Formulation per Acre

0.5 to 4 oz

Pounds Active Ingredient per Acre

0.0078 to 0.0625

Precaution and Remarks

May be applied to bermudagrass, zoysiagrass and centipedegrass on professionally managed sports facilities at professional and collegiate levels, golf courses, sod farms, roadsides, industrial and commercial lawns. For annual bluegrass control, apply November through December and again February through March if needed at 2 ounces per acre. May be applied 10 to 14 days prior to overseeding. For overseeded removal, apply 2 ounces per acre 3 to 4 weeks before desired removal date, and repeat 3 weeks later if needed. For weed control along roadsides, apply 4 ounces per acre if single application only. A nonionic surfactant at 0.25% by volume or an oil adjuvant such as crop oil concentrate and modified seed oil at 1% by volume are required. Do not apply to cool-season turfgrasses, residential lawns or newly sprigged/sodded bermudagrass.

Preemergence Control

Herbicide and Formulation

metsulfuron + rimsulfuron, MOA 2 + 2 (37 WG)

Amount of Formulation per 1,000 sq ft

0.0344352 oz

Amount of Formulation per Acre

1.5 oz

Pounds Active Ingredient per Acre

0.0346875

Precaution and Remarks

Use on well established bermudagrass and zoysiagrass grown on nonresidential turf including golf courses, sod farms, industrial and commercial lawns, and professionally managed college and professional sports fields. Overseeding can occur 2 months after application. Include a nonionic surfactant at 0.25% by volume.

Preemergence Control

Herbicide and Formulation

sulfosulfuron, MOA 2 (75 DG)

Amount of Formulation per 1,000 sq ft

0.017 to 0.046 oz

Amount of Formulation per Acre

0.75 to 2 oz

Pounds Active Ingredient per Acre

0.035 to 0.09375

Precaution and Remarks

May be applied to certain ornamental native grasses and also bermudagrass species, zoysiagrass, centipedegrass, St. Augustinegrass, and kikuyugrass grown on sod farms, golf courses (excluding greens), commercial and residential turf that is highly managed, and other noncrop areas. Use 1.5 to 2 ounces per acre for fall annual bluegrass control 7 to 10 days before overseeding. Use 0.75 to 1.25 ounces per acre for fall or winter control in nonoverseeded bermudagrass, and reapply if needed but not before 21 days after initial application. For tall fescue control, two applications may be required at 4- to 10- week intervals. Perennial ryegrass control not as complete as with foramsulfuron, rimsulfuron, or trifloxysulfuron. Use a nonionic surfactant at 0.25% by volume. Do not exceed 2.66 ounces per acre per year.

Preemergence Control

Herbicide and Formulation

trifloxysulfuron, MOA 2 (75 WG)

Amount of Formulation per 1,000 sq ft

0.0023 to 0.0129 oz

Amount of Formulation per Acre

0.1 to 0.56 oz

Pounds Active Ingredient per Acre

0.0047 to 0.0263

Precaution and Remarks

May be applied to residential bermudagrass and zoysiagrass and also on golf courses, sod farms, and other nonresidential turf areas. A nonionic surfactant at 0.25 to 0.5% by volume is recommended. Temporary discoloration may occur if used with MSO or COC. May be applied 3 weeks prior to overseeding. Use rates of 0.1 to 0.3 ounces per acre to remove overseeded perennial ryegrass and Poa trivialis to aid bermudagrass spring transition. Labeled turf species can be seeded or sprigged into treated areas 4 weeks after application.

Preemergence Control

Herbicide and Formulation

atrazine, MOA 5 (4 L) (90 DF,90 WG)

Amount of Formulation per 1,000 sq ft

0.75 to 1.5 fl oz 0.025 to 0.05 lb

Amount of Formulation per Acre

1 to 2 qt 1.1 to 2.2 lb

Pounds Active Ingredient per Acre

1 to 2

Precaution and Remarks

Use on centipedegrass, St. Augustinegrass, and dormant bermudagrass. Apply Nov. 15 to Dec. 31. Follow label directions.

Preemergence Control

Herbicide and Formulation

simazine, MOA 5 (90 WDG, 90 DF) (4 L)

Amount of Formulation per 1,000 sq ft

0.4 to 0.8 oz 0.75 to 1.5 fl oz

Amount of Formulation per Acre

1.1 to 2.2 lb 1 to 2 qt

Pounds Active Ingredient per Acre

1 to 2

Precaution and Remarks

Use on bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass. See label for instructions on newly sprigged turfgrass or on hybrid bermudagrass. Apply Nov. 15 to Dec. 15. Follow label directions.

Presentations

Publications

Species Data

Seedhead/Flower

light-colored panicle seedhead

autopsy3
autopsy3
autopsy3
p1040687
p1040687
p1040687
p1050183
p1050183
p1050183
seedhead
seedhead
seedhead
weed51
weed51
weed51
weed5
weed5
weed5
Vernation type

leaves folded in the bud

vernation
vernation
vernation
Ligule Type

membranous; sharp pointed entire, 0.04 - 0.12 inches (1 - 3 mm) long

ligule
ligule
ligule
Growth Season/Life Cycle

winter annual weed

Auricle type

absent

Leaf blade tip shape

boat shaped; smooth above and below, not glossy, light green; two distinct, clear lines, one on each side of the midrib

boattip3
boattip3
boattip3
Leaf blade width

0.08 - 0.1 inches (2 - 3 mm) wide

Stolon Presence

absent

Rhizome Presence

absent

Collar Type

divided; distinct, not hairy, V-shaped

collar
collar
collar
vernation
vernation
vernation
Sheath Margin

open part way only

Sheath Type

flattened; slightly sharply creased

vernation
vernation
vernation