David M. Kopec, Extension Turfgrass Specialist
Winter weeds can sometimes be a real problem on turfs in Arizona. Here
are some tips relative to winter and spring weed control.
Low elevation - bermuda country, 3500 ft. elevation, or less.
Winter weeds in parks, commercial properties and golf courses often include annual bluegrass, (Poa annua) which is a prolific seed producer and grows willingly at low mowing heights in compacted and wet soils. In bermudagrass turf which has been overseeded with perennial ryegrass, PROGRASS (AI= ethofumesate) can be applied for pre and post emergence of annual bluegrass. It works best when the weed is young (1 month old or less). However, I think you may still get some control now in high profile areas. There's only time for one application in 1994. The label states to apply PROGRASS before February 1, or so. This is because the herbicide can injure the bermuda if it is not dormant. So check out the bermuda before any application is made. I like to look at a solid stand of non-seeded bermuda to see if its dormant or not. PROGRASS is not registered for use on greens.
PRINCEP or AATREX (simizine) is used in other parts of the U.S. to control annual bluegrass in non-overseeded bermudagrass turfs. It provides pre and post emergence control of young plants. It's best to wait next year for this one! Also in non-overseeded bermuda areas, ROUND-UP SENCOR, or KERB can be used to control annual bluegrass and certain broadleaf weeds. For these, the bermuda must be dormant!
Broadleaf weeds that are up include burr clover, mallow, a little black medic, and some assorted mustards on border areas. These can be controlled effectively with the hormone regulating products which contain either/or combinations of 2,4-D, mecoprop, dicamba, trichlopyr, and clopyralid. Trichlopyr and clopyralid are products released relatively recently. They are sold as TURFLON ESTER (trichlopyr-ester), TURFLON II AMINE (trichlopyr and 2,4-D amine salt), TURFLON D (trichlopyr plus 2,4-D) and CONFRONT (trichlopyr plus clopyralid).
The active ingredient clopyralid provides good control of legume weeds, (clovers, medics, etc.).
Spring weeds can be nipped in the bud with proper application of a pre-emergence plant protectant.
Crabgrass and cupgrass germinate in the lower elevations starting at around February 15 to March 1. The warmer the soil temperatures, the quicker it happens. Areas with low turf density and open canopies from winter traffic have higher soil temperatures, so don't wait till you see these grasses in areas where there has been a strong history of these weeds. Here's the scoop.
Bermudagrass Greens: Products labeled with the Federal EPA include bensulide (BETASAN, BENSUMEC, LESCOSAN), bensulide + oxadiazon, (GOOSEGRASS and CRABGRASS CONTROL), DIMENSION 1EC (active ingredient is dithiopyr) and PRE-M 60 D6, WEEDGRASS CONTROL 60wp (active ingredient is pendimethalin).
Bentgrass Greens: BETASAN, BENSUMEC, LESCOSAN, (active ingredient is bensulide). Bensulide plus oxadiazon which is GOOSEGRASS/CRABGRASS CONTROL is also labelled. DIMENSION is also labelled. I have used betasan on greens safely. I have not tried the bensulide + oxidiazon mixture. I have damaged bentgrass severely using DIMENSION at label rates or less. The label gives extensive precautions -- in otherwords, your on your own.
Applying any herbicides to bentgrass at the low elevations is inherently very risky in my opinion. Problems can show up 4 months later -- like no grass!
Goosegrass appears to germinate about a month later than crabgrass. Therefore, you can follow the "split application"
program on the label, applying the second application in 7-8 weeks. This covers the initial crabgrass germination, plus the goosegrass, and hopefully, khakiweed. Weak and open turfs can still sport these weeds in mid-late summer. Khakiweed is a summer broadleaf weed. The herbicide GALLERY (ai=isoxyben) should provide pre-emergence control of this weed.
Bermuda Fairways, Parks and General Grounds: BALAN 60DF, BARRICADE (prodiamine), BETASAN (bensulide), DACTHAL 6F, (dcpa) DIMENSION 1EC, PRE-M 60DG, REGALSTAR 1.5G, RONSTAR 50WP, XL (balan and surflan) TEAM 2G (balan and treflan) are typical pre-emergence plant protectants. Note the label if the specific product is safe for overseeded turf. For example, SURFLAN and XL both contain oryzalin, which will damage the ryegrass!
Post emergence control of crabgrass and cupgrass can be achieved with MSMA in multiple applications 10 days apart. MSMA and SENCOR (metribuzin) will aid in the control of goosegrass. In the reports I have sent you in the past, I noted that MSMA plus BASF 514 did a good job on crabgrass control, post emergence. However, BASF 514 has not reached the market place to date. ILLOXAN is also available for post emergence control of young goosegrass.
Khakiweed can be controlled with repeat applications of 2,4-D,
and or trichlopyr. It has a very waxy coating, so include a surfactant.
This will cause more damage to the turf, so consider spot applications.
New khakiweed seedlings will follow --so get ready.
Listing of products or exclusion of others does not mean endorsement. Similar products with same active ingredients may be available at different concentrations. Always read the label to check for limitations, conditions of application, specific weed control, and turfgrass tolerance. This is the responsibility of the user!!
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.