David M. Kopec, Extension Turfgrass Specialist
At the higher elevations of Arizona, (4500 feet and above), cool season grasses can be used for turf. At elevations of 6000 feet and above, it's the only way to fly. The same principles of turfgrass weed control (pre-emergent and post emergent control) apply to cool season grass maintenance. There are some difference's that exist. These include:
1) different weeds often prevail at higher elevations
2) the "proper time" to apply an applicable pre-emergent is different because of "real winters". In other words, spring applications are really made in April-May. Also,
3) there are more perennial weeds at higher elevation, and
4) different grasses are used compared to bermuda 'down below'. The tolerance of herbicides among the cool season grasses is not necessarily the same for a given herbicide on bermuda, nor are the same chemicals always registered for both cool and warm season turfs.
So, let's go! At the higher elevations, golf courses will use almost exclusively creeping bentgrass (Agrostis palustris) for greens. It's too late to do anything for the Poa annua that's already up.
Annual bluegrass continues to germinate forming new plants in the spring, especially at the higher elevations. BENSULIDE (chemical name is betasan) sold also as the products BETASAN, BENSUMEC, LESCOSAN, can be applied to spring bentgrass greens that are not being seeded. Watch the label rates carefully. Too much can severely stunt root initials and stolon pegging in weaker areas. This application should take care of the crabgrass as well. Goosegrass (a remote problem, but unfortunately a good seed producer at all mowing heights) will germinate about 4 weeks later than crabgrass. Since a second application of a pre-emergent on bentgrass greens may not be desirable, you should know which weeds are more of a problem, the Poaannua, or the crabgrass/goosegrass, and apply at the proper time for either major problem.
Most other turfed areas at high elevations consist of Kentucky bluegrass, perennial ryegrass, and some tall fescue. Mixtures of Kentucky bluegrass with rye, and Kentucky bluegrass with fine fescue (creeping-red fescue) are also used. These grasses are found in parks, cemeteries, right of ways, golf course tees, roughs and fairways.
For these grasses, some of the Page 2.
BALAN (benefin) BENSULIDE (betasan) DIMENSION (dithiopyr) RONSTAR (oxadiazon) PROWL (pendimethalin) BARRICADE (prodiamine) DACTHAL W-75 (dacthal) TUPERSAN (siduron) ACCLAIM (fenoxyprop) GOOSEGRASS/ CRABGRASS CONTROL (bensulide + oxadiazon) TEAM (benefin + treflan). GALLERY (isoxaben) is good for pre-emergent of most broadleaf weeds, which include spurges, mustards, little mallow, slender and broadleaf plantain, henbit, and creeping woodsorrel.
BALAN + SURFLAN sold as (XL) can be used on tall fescue only. Do not use on Kentucky bluegrass or ryegrass. The above chemicals should control most pre-emergent weed problems, which are mostly grasses. If the broadleafs are a problem in specialty areas, check out the GALLERY label. GALLERY is a pre-emergent herbicide for broadleaf weeds. Spurge can also be controlled by pre-emergent products. Products which contain the following (prodiame, pendimethalin, balan + treflan, balan + surflan) will also control spurge.
Post emergent products can be used to control many of the broadleaf perennials, which last all year at the higher elevations. These include some of the mallows, clovers, medics, plantains, and already established spurges and oxalis (woodsorrel).
Some of the most popular products include the following:
1) the active ingredient 2,4-D and dichlorprop, as 2D + 2DP AMINE, TURF D + DP, SCOTTS FLUID BROADLEAF WEED CONTROL, WEEDONE DPC, WEEDONE AMINE, LESCO 2,4-D + DICHLORPROP GRANULAR HERBICIDE.
2) 2,4-D + dichlorprop + dicamba (SUPER TRIMEC)
3) 2,4-D, + MCPP + dicamba (BROADLEAF WEED KILLER, BRUSHFIRE, BURNOUT, BRUSH WHACKER, LEBANON BROADLEAF WEED KILLER, MECAMINE-D, 3 WAY LAWN KILLER, 3 WAY SELECTIVE HERBICIDE, TREX SAN, TREX SAN BENT, TRIMEC BENTGRASS, FORMULATION, TRIMEC CLASSIC, TRIMEC SOUTHERN)
4) 2,4-D + MCPP + dichloroprop (TRI-AMINE, TRI-AMINE GRANULAR WEED KILLER, SPOT WEED KILLER TRI-ESTER)
5) 2,4-D + MCPP + MSMA + dicamba (TRIMEC PLUS).
There are many product combinations of the 2,4-D and phenoxy type post emergent herbicides, as you can see!
6) dicamba (BANVEL)
7) trichlopyr (TURFLON ESTER)
8) trichlopyr + 2,4-D (TURFLAN II)
9) trichlopyr + clopyralid (CONFRONT). The clopyralid component is very
active on the
legumes (clovers, medics)
11) mecoprop (MCPP, LEXCOPEX, MCPP-4 MCPP-4K, MECOMEC, SUPER LEXCOPEX)
At higher elevations, there is more yellow than purple nutsedge. IMAGE suppresses purple nutsedge better than yellow nutsedge, but it will severely damage or kill cool season grasses. The chemical bentazon (BASAGRAN) is used successfully in the midwest to control yellow nutsedge. I don't know if it works well here. MCPA, MCPA + dichloroprop + MCPP may suppress yellow nutsedge.
MSMA will burn the foliage of both the nutsedge and the turf. It's often non-selective at rates needed to burn the foliage of the weed.
For non-selective control in landscapes, there is always ROUND-UP (glyphosate) and MSMA.
For control of grasses among landscape plants, FUSILADE OR VANTAGE (fluazifop), or POAST (sethoxydim) can be used.
For eliminating clumps of tall fescue in Kentucky bluegrass turf SCOTTS TFC (chlorsul furon) applied in the fall will weaken the fescue severely, so it is overcome in the following spring. Spring applications are not recommended.
The chemical ILLOXAN (diclofop) can be used to kill young goosegrass plants. Check the label for tolerance
For a broad list of product and tolerance references, see "Turfgrass Chemical Update" in Grounds Maintenance, January 1994.
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.