Clumps of tall fescue are objectionable in Kentucky bluegrass – what’s the best control method? Many have asked this question recently. There are both long and short answers to this difficult question, and neither are ideal.
Short(er) answer – mechanical or nonselective control. Manually remove clumps of tall fescue, and seed, sod, or allow Kentucky bluegrass rhizomes to fill the gaps left behind. Nonselective control is possible with glyphosate, and is most effective in late summer to early fall. Preliminary results from an ongoing UNL study indicate that tall fescue may be scalped as soon as one day before or after treatment in fall without reducing control. In fact, excellent control was achieved even when tall fescue was scalped one hour before applying glyphosate. An evaluation of the effects of timing scalping around spring applications of glyphosate is underway.
Long answer – selective control. There are currently no herbicides labeled for the selective control of tall fescue in Kentucky bluegrass in lawns, parks, athletic fields, or golf courses. If the turf you manage falls under any of these sites, your best bet is to refer to the previous section. Following are answers for other questions frequently asked about tall fescue control.
- If you manage industrial turf (rights of way, etc.), chlorsulfuron (sold as Telar XP) will control tall fescue (and perennial ryegrass) without injuring Kentucky bluegrass. Chlorsulfuron was previously labeled for more turf sites when sold as Corsair, but this product is no longer available.
- Metsulfuron (sold as Manor or Mansion) is labeled for ryegrass control in many Kentucky bluegrass sites, and may also provide some measure of tall fescue control. However, because only lower rates are safe on Kentucky bluegrass, metsulfuron will likely only injure tall fescue. The Nufarm website currently indicates that Manor is not registered for use in Nebraska, but the Nebraska Department of Agriculture Pesticide Regulations website shows active registrations for both Manor and Mansion.
- Sulfosulfuron (sold as Certainty) will control tall fescue, but is no longer labeled for use in Kentucky bluegrass (or creeping bentgrass).
- Many sulfonylurea herbicides (e.g. Revolver) will safely control tall fescue and other cool-season grasses in buffalograss. Additionally, nonselective herbicides may be applied after buffalograss loses color in fall for “selective” control of cool-season grasses, including tall fescue.
Bottom line. Mechanical removal or nonselective herbicides are the best options for tall fescue control in most turf sites. Chlorsulfuron may be used in industrial sites.
Cole Thompson, Asst. Prof. & Extension Integrated Turfgrass Management Specialist, cole.thompson@unl.edu