February Issue 2001

Spring Touch-Ups and Weed Control

David M. Kopec, University of Arizona

It finally happened, winter is gone. No more frost delays, no more ice on the cart paths! The ‘other side of January' is now here. These are among the very best growing conditions for all cool season grasses, which includes all overseed, and bentgrass.

Now is the time that greens and tees will respond to fertilization. Highly trafficked greens, and green exits should respond to narrow-solid tine aerification, and/or water injection aerification. Follow this with application of a water soluble fertilizer (in the nitrate form) and you should see quick responses in growth, color and density. Examine weak areas to see if there are living tillers in sufficient numbers before you decide to add some new seed down again. Patches that need reseeding will respond very quickly to pre-germinated seed. This will save 10 days or more on germination and emergence. Just make sure that the pre-germinated seed is covered with a small "dusting" of composted manure/sand mix. This is critical when using pre-germinated seed! Non-overseeded areas may have "winter weeds" in the roughs and back of the surrounds. Light rates of Round-up are good for getting rid of Poa annua, as well as the winter brome grasses, and most broadleaves. Make sure there is no tracking! You will need to close down one afternoon to avoid this. Diquet (REWARD) is also good, and packs a wallop when used as a directed spray on dormant bermuda!

If tees are completely hammered, you can still slitseed in multiple rows with ryegrass. Follow with rolling. Check throughout the day and irrigate these re-seeded tees when there is 3 minutes before the next golfing group. You'll be surprised how often this occurs and how the re-seed will respond accordingly.

Bentgrass greens, which feature high shoot density cultivars, will need to be watched closely for canopy thinning. Groom as needed, and as often as needed. Practice light grooming on a repeat basis, rather than trying to ‘bite' into the canopy. This injures the grass by ‘wringing' the stolons and produces a ‘stodgy' looking turf. The bent will have yellow leaves and appear ‘wet,' and give untrue rolls. Rather, groom more frequently at 1/32" to 1/16" or so below the bedknife. A good rule of thumb is to set the groover such that you see light lines when walking behind the mower, but you see no (or minimal) lines when standing on the side of the mower. Don't ("double" groom on clean-up passes. This will cause too much wear. Shut off the groomer when making the clean-up pass.

Poa annua on the greens?

If your greens are new, take a "tupperware party" out and plink it out with knives. Throw the plants away in the dumpster, since Poa annua seed is quickly viable, even when it is in the seed head! Got lots of Poa around green banks? Label the Poa with flags. Mix up some EMBARK LITE at label rates and spray the Poa with a hand-sprayer until it is all wet. Remove the flags. This will stop the Poa temporarily from flowering, and ‘flagging' will look better than using a spray-dye in the tank mix.

Overseeded areas with Poa can be treated with EMBARK LITE or PROXY. EMBARK T/0 is labeled for use on golf greens. Both show seed head suppression for 2-3 weeks, and require repeat applications. It is good to include chelated iron when using EMBARK LITE. Cold weather damage can occur when using EMBARK. Remember that you must treat Poa for seed head supression until late spring when it should die from the heat. If you "miss" the late season applications, the seed heads will explode.

For Spring pre-emergence control, make sure that you know which are your most problematic weeds. Also, you may be able to save money on applying different herbicides to non-overseeded versus overseeded areas. Here, turf tolerance (of the overseed) is the issue. Most dinotroanaline pre-emergents are good for controlling southwest cup-grass and crabgrass (we have lots more cupgrass than crabgrass). These include BARRICADE (prodiamine), PRE-EM (pendimethalin), BAYLAN (benafin), TREFLAN (trifluralin), BENSULIDE (betason), and SURFLAN (oryzalin). SURFLAN cannot be used on ryegrass. Check for application of prepackage mixed like XL (SURFLAN and BAYLAN) and TEAM (Treflan and Baylon). Apply these products by February 15 (Yuma), and March 1 in Tucson and Phoenix. DIMENSION (dithiopyr) is excellent for cupgrass control, and also has some post-emergence activity when cupgrass/crabgrass is still very juvenile (2-3 leaf and 1 tiller stage). RONSTAR (oxadiazon) is excellent for pre-emergence control of goosegrass. This is a problem in partially shaded areas, and compacted areas around cartpaths. You can apply this to areas where this is a known problem. Goosegrass comes out of the ground at warmer soil temperatures than crabgrass/cupgrass. So apply this March 1 in Yuma, March 5-10 in Phoenix, and March 15-20 in Tucson.

For greens, BENSULIDE (betason) is labeled, as is REGAL STAR (betasan and oxadiazon). Always read the label, and always calibrate before using spraying. If you have spurge and khakiweed populations that have been out of control in the past, consider GALLERY (isoxaben).

Return to Turfgrass Research
[Cooperative Extension] [AgInfo] [UAInfo]

University of Arizona Cooperative Extension
4341 E. Broadway Road
Phoenix AZ 85040-8807
602-470-8086 FAX: 602-470-8092

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.

All contents copyright © 2004. Arizona Board of Regents.