Clark Talks Turf: Digging deep into fraze mowing

Brian Whitlark is a USGA agronomist in the West Region. Brian conducts course consulting visits, writes for USGA publications and is a conference speaker. Brian has observed several golf courses using fraze mowing to improve their turf. You may reach Brian at bwhitlark@usga.org for more information.

Q: What is the fit of fraze mowing in your region?

Fraze mowing is still in its infancy in the Southwest. Superintendents are still in the learning mode with fraze mowing. Most superintendents start by fraze mowing a driving range tee, and if satisfied start fraze mowing tees, fairways and approaches. Currently, most of the fraze mowing is done by contract providers.

Bermudagrass is a prolific thatch producer, and over a few years a large accumulation of organic matter makes the soil surface hydrophobic, which impedes water movement into soil. Organic matter accumulation also reduces playing quality and makes winter overseeding a challenge because seed does not reach the soil surface.

Superintendents have tried all sorts of cultivation techniques to reduce organic matter accumulation with limited success, thus the interest in fraze mowing to reduce organic matter accumulation.

So far, golf courses in the Southwest have used an aggressive form of fraze mowing to reduce organic matter accumulation. Typically, the first pass is with the fraze mower set at 0.75 inch deep, followed by a second “clean-up” pass with the mower set at 0.25 inch. This results in all the thatch and organic matter being stripped off, leaving behind only surface stolons and underground rhizomes for recovery.
An additional benefit of fraze mowing is the removal of annual bluegrass (Poa annua) seed. Removal of annual bluegrass seed greatly reduces the annual bluegrass population during the next few years.

Q: Describe the recovery process after fraze mowing.

Some superintendents topdress right after fraze mowing because it’s an excellent opportunity to apply up to 0.25 inch of sand to smooth the surface and improve the soil profile. The sand also helps the bermudagrass recover more quickly. The rate of recovery depends on the time of year the fraze mowing occurs, the aggressiveness of fraze mowing and the quality of the bermudagrass stand prior to mowing. Some courses have had success seeding bermudagrass to enhance recovery where the stand was thin prior to fraze mowing.

In the Phoenix area, aggressive bermudagrass growth doesn’t really begin until around July 4, so superintendents schedule their fraze mowing around this time to take advantage of the aggressive growth. Depending on the aggressiveness of fraze mowing, it will take about three weeks for the bermudagrass to recover enough to allow the golf course to reopen. This is not full recovery, but sufficient to reopen for play.

Q: What’s done with all the debris generated by fraze mowing?

Debris disposal is a huge challenge. Fraze mowing generates a tremendous volume of debris. Some golf courses pay to have the debris hauled away, which is costly; some golf courses spread the debris in the rough, which is a problem if one of your goals for fraze mowing is to remove annual bluegrass seed; and some golf courses dig pits on underused portions of the property and bury the debris. If the debris is clean of weed seeds it can be a valuable source of sprigs to fill in thin areas in roughs. I’m not aware of any simple, inexpensive method to dispose of the debris.

Q: How do you see fraze mowing being used in the Southwest?

This is something superintendents will figure out once the process is used more widely. One approach might be to aggressively fraze mow four or five fairways a year every four years or so. Another approach might be to aggressively fraze mow all the fairways one year, followed by several years of less aggressive fraze mowing.

Everyone needs to come to terms with the fact that fraze mowing means closure of all or a portion of the course during the recovery period. The barren look of the turf right after fraze mowing can be a shock, and debris disposal is a challenge.