Annual Bluegrass

Selective preemergence

See preemergence herbicides listed for annual grasses.

Selective preemergence and early postemergence

ethofumesate (Poa Constrictor Herbicide, Prograss Herbicide, Prograss SC Herbicide, Thrasher)

Rate After seeding and before weeds emerge: use 0.20 to 3 pints/a. Postemergence Applications: use 2.25 to 3 pints/a no later than the 4-leaf stage of the weed. Harder-to-control weeds must be treated by the 2-leaf stage of the plant. For established grasses: Use 2.25 to 3 pints/a both pre- and postemergence for perennial ryegrass and tall fescue.

Time Apply to grasses listed as tolerant on label, when annual bluegrass is at less than the 4-leaf stage.

Remarks Available only as an emulsifiable concentrate. It gives effective preemergence and early postemergence control of annual bluegrass in new seedings of perennial ryegrass.

Caution Inhibits germination of most desirable cool-season grasses, other than perennial ryegrass. Highly toxic to seedling fine fescues. Surface organic matter decreases the effectiveness of ethofumesate, so remove thatch and other debris before applying.

Site of action Group 16: unknown

Chemical family Benzofuran

Selective postemergence

amicarbazone (Xonerate Herbicide)

Oregon only

Rate 1 to 10 oz/a Xonerate

Time Apply for selective postemergence and some preemergence control of certain weeds in established turfgrasses.

Remarks Xonerate is a 70% WDG formulation. Controls annual bluegrass in established creeping bentgrass, Kentucky bluegrass, fine fescues, tall fescues, and perennial ryegrass.

Caution Do not apply to grasses under environmental stress or at temperatures of 85°F for most cool-season grasses and not above 80°F air temperatures for creeping bentgrass tees or roughs. Do not apply if soil pH is above 7.4. Do not mix or fill within 50 feet of any wells, ponds, ditches, streams, or lakes. Do not apply more than 10.25 oz/a in one application or per year. Do not apply to sites where annual bluegrass is maintained as a desirable turfgrass. Xonerate does not control perennial broadleaf weeds in turfgrasses. Apply with labeled tank-mix partners in a minimum of 20 gal/a of spray volume using broadcast boom equipment. Read label carefully for additional precautions about application timing and intervals. Overlap of application can cause turf damage.

Site of action Group 5: Inhibition of photosynthesis at photosystem II

Chemical family Carboxamide

bispyribac-sodium (Velocity SG Herbicide)

Rate 6 oz/a or 30 gal ai/a (0.066 lb ai/a). For conversion to creeping bentgrass or perennial ryegrass: Make 4 applications at 6 oz/a on a 14- to 21-day interval.

Time Apply when grass is actively growing, but before weeds form seed heads.

Remarks Velocity may mildly discolor creeping bentgrass and perennial ryegrass. Discoloration begins 3 to 10 days after application. Vigorously growing grasses should outgrow symptoms within 3 to 14 days. If temporary turf chlorosis is a concern, avoid treating small patches of turf that are surrounded by untreated areas of turf. Velocity performs best under sunny conditions when daytime temperatures are 65 to 80°F during and after application.

Caution Do not apply Velocity to turfgrass with symptoms of heat stress or if significant heat stress is expected. Velocity may increase the susceptibility of creeping bentgrass to Pythium blight when conditions are favorable for infection. Do not apply to creeping bentgrass or perennial ryegrass mowed to less than 0.375 inch. Do not apply to golf greens and roughs. Velocity may not be effective against all biotypes of annual bluegrass.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Pyrimidinylthiobenzoate

ethofumesate (Poa Constrictor Herbicide, Prograss Herbicide, Prograss SC Herbicide, Thrasher)

Rate New seedings applied preemergence of weeds: use 0.2 to 3 pints/a. Postemergence applications: use 2.25 to 3 pints/a no later than the 4-leaf stage of the weed. Harder-to-control weeds must be treated by the 2-leaf stage of the plant. For established grasses: use 2.25 to 3 pints/a both pre- and postemergence for perennial ryegrass and tall fescue.

Time Apply to grasses listed as tolerant on label, before annual bluegrass reaches the 4-leaf stage.

Remarks Effective only in a series of three or more treatments; single treatments are not effective. Some perennial strains of annual bluegrass may not be affected.

Caution Kills fine fescues and roughstalk bluegrass and causes unsightly injury to most bentgrasses. Assess components of the turf carefully before beginning treatment.

Site of action Group 16: unknown

Chemical family Benzofuran

Selective growth suppression

paclobutrazol (Turf Enhancer 2SC, Trimmit PGR)

Rate Use 0.25 to 0.50 lb ai/a. If annual bluegrass is a significant portion of the population, it would be a good idea to reduce the application rate by 50%. Two additional sequential applications 8 weeks apart are allowed (for a total of 3 applications) per year.

Remarks Available in liquid (2SC) and granular formulations (mixed with fertilizer). Selectively suppresses annual bluegrass growth, allowing tolerant grasses to dominate turf. Long-term success requires annual re-treatment. Tends to be more effective in turf mainly with annual Poa annua biotypes. Paclobutrazol is labeled for use on bentgrass, Kentucky bluegrass, and perennial ryegrass.

Caution Not recommended for turf with more than 70% annual bluegrass. Do not use during periods of extreme environmental stress (e.g., heat, cold, drought). At high rates, Kentucky bluegrass and bentgrass turf may be discolored temporarily.

Site of action Gibberellin biosynthesis inhibitor

Chemical family Class B plant growth regulator

Selective seed head suppression

ethephon (Proxy, Verve PGR, Ethephon 2 Plant Regulator, Ethephon 2 SL, Ethephon 2, Excelero PGR, NuFarm Ethephon 2 PGR, Oskie Plant Regulator, Helena Oskie Plant Regulator)

Rate 5 fl oz in 1 to 2 gal water/1,000 sq ft. See label for specific application intervals.

Time Apply to golf, parks, and sports turf. Not for residential use.

Remarks Proxy is used to suppress seed head formation in Poa annua and white clover, among others, and also to suppress growth of certain cool-season grasses. It is foliar-absorbed and is most effective on actively growing, healthy turf. Apply in a sufficient volume of water to provide uniform coverage. Proxy is rainfast in 2 hours. A spreader/sticker is not necessary. Do not reenter treated area until dry. Delay mowing until the day after the application.

Caution Do not treat turfgrasses with poor root systems, or those growing under stress due to poor soil conditions. Do not use if thatch is excessive. Do not apply Proxy through any type of irrigation system. Mix only the amount of product you expect to use each day. Do not allow mixed solution to stand overnight. Scalping may occur on creeping bentgrass cultivars after more than two applications of Proxy for Poa seed head suppression.

Site of action Enhances release of ethylene gas

Chemical family Phosphinic acid

Turfgrass growth suppression

maleic hydrazide

Rate 3.0 lb of product/1,000 sq ft

Time Apply this product to green grass, since brown grass will not absorb the spray. Use of this product is limited to one application per year made either in the Fall or the Spring followed by correct maintenance procedures to produce required turf growth control.

Remarks For spring application (April 15 to June 1) use 1.75 gal product in 50 gal water/a to reduce or eliminate mowing. For fall applications, (Oct. 1 to Nov. 15) use 2.25 gal of this product in 50 gal of water/a to reduce growth next season. The fall treatment should also be applied to green grass before it becomes dormant.

Caution Do not apply during the summer since most permanent grasses become partially dormant in the summer. This product should be applied at temperatures below 85°F under high temperatures and low humidity conditions, this product will crystallize on the leaf surface preventing normal absorption into the plant. To obtain the desired results, the plants should not be stressed from either too much or too little water before or after application. Make only one application per season.

Site of action mitotic inhibitor

Chemical family Class C plant growth regulator

mefluidide (Embark T & O Growth Regulator, Embark 2S, EMBARK 2S IVM)

Rate Apply at 0.75 to 1.8 fl oz/1,000 sq ft depending upon grass species and mowing height; Embark 2S: 0.5 to 4 pints/a; Embark 2S IVM 24 to 32 fl oz/a alone or at 8 fl oz/a in combination with three other possible growth regulators listed on the label. See Table 1 on label for tank mixtures possible on cool season noncropland sites.

Time Embark T & O Growth Regulator may be applied to actively growing cool-season and warm-season turfgrass in commercial or residential lawns, schools, golf courses, recreational areas, and athletic fields. For fall applications, apply at least 1 month before winter dormancy. In turfgrass renovation programs, areas treated with Embark may be reseeded 3 days following application (except in California, where reseeding may not occur within 2 weeks). Embark 2S IVM is for use on established noncropland areas such as highway rights-of-way, municipal, state and federal lands and commercial/industrial areas. Embark 2S IVM is not to be used for sod, commercial seed production or research purposes.

Remarks Embark suppresses seed head formation, decreases the amount of clippings and reduces the mowing requirements for up to 4 weeks. Grass may be mowed up to two days before applying Embark. Clippings and other debris should be removed before spraying. If mowing removes most of the green leaf tissue, spraying should be delayed until sufficient new growth develops to assure product absorption into green leaves. Turf color and quality during week 1 through 3 of the growth regulation period may be improved with an application of FeRROMEC AC Liquid Iron. Schedule the application of FeRROMEC AC Liquid Iron within 10 days before the application of Embark T & O Growth Regulator. Optimum seed head control may not be obtained if rainfall or overhead irrigation occurs within 8 hours following application. For athletic fields, Embark can be applied with line marking paints to limit the number of applications of field lines. Generally, one application of Embark with the line marking paint is recommended per season.

Caution Do not apply directly to water or to areas where surface water is present or to intertidal areas below the mean high water mark. To avoid turf injury, use only on turfgrass that is reasonably free of stress from diseases, insects, excess heat, cold or frost, drought or excess rainfall/irrigation, shaded areas, low soil pH, nematodes, improper mowing or improper applications of fertilizer and pesticides. Multiple applications may be made, but wait at least 6 weeks between applications.

Site of action mitotic inhibitor

Chemical family Class C plant growth regulator

trinexepac-ethyl (Game Up PGR, Goldwing PGR, Governor Growth Reg., Groom PGR, Primo MAXX, Podium, Provair PGR, T-Nex 1AQ)

Rate Rate varies depending upon the product, turfgrass species, mowing height and length of suppression desired.

Time Apply to actively growing grass, including home lawns, parks, recreation areas, golf course roughs, cemeteries, business sites, sports fields, and sod farms that are not under stress.

Remarks Primo MAXX reduces mowing frequency and the amount of grass clippings. It also increases turfgrass density, color, and quality. Useful in difficult-to-mow areas; can minimize the need to edge along sidewalks, curbs, parking lots, driveways, flower beds, and fences and around posts, storage sheds, and trees. Primo MAXX reaches the growing point by foliar uptake and is rainfast after 1 hour. Water is not needed to activate it.

Caution Any cultural practice that affects turf growth and vigor will influence turf response to Primo MAXX. Rates in the table on the label provide about 50% growth inhibition over a 4-week period with little or no discoloration. With less-than-optimal growth conditions, rates may have to be reduced by 50% due to stress. Multiple applications of Primo MAXX can be made each growing season, but do not exceed a total of 7 fl oz/1,000 sq ft per year. If turf is going into dormancy due to high or low temperatures or lack of moisture, reduce Primo rate. To minimize turf injury, apply Primo MAXX, then wait at least 4 hours before mowing; or mow first, wait at least 1 hour, then apply Primo MAXX.

Site of action Late gibberellin (GA1) biosynthesis inhibitor

Chemical family Class A plant growth regulator