www.sportsturfonline.com26 SportsTurf | August 2013

FieldScience | By Jerad Minnick & Allen Reed

Challenge: Thatch/organic build-up onbermudagrass athletic fields.

Issues challenge is causing: Reduceddurability, including plants growing verticalup through the thatch instead of laterally soit is not as strong and healthy as needed;and thatch breaking down into organic ma-terial is full of fines, creating surface com-paction and slickness.

• Isolated dry spots due to inconsistentrooting

• Increased water requirement for rye-grass overseeding (seed is growing in thatchinstead of in the soil)

• Decreasing ryegrass overseeding dura-bility (seed is growing in thatch instead ofsoil)

Concept solution: Fraze mow to cleanout thatch completely. Thatch managementon bermudagrass is an on-going challenge

for sports field managers. Advancements inbreeding to create more aggressive bermuda-grass varieties create a solution for high traf-fic fields. But conversely, vigorous growthcompounds the challenge of maintainingthatch and organic material build up.

Verticutting, core aeration, and topdress-ing are the accepted maintenance practiceswith which sports field managers addressthatch and organic material build up on allgrass fields (cool or warm season). Accord-ing to data from the International SportsTurf Research Center, a verticutting ma-chine with 3mm blades on 1” centers re-moves 11.81% of the surface area. Coreaeration with 5/8” hollow tines on 2”x 2”spacing removes 7.67%. Thus ultimatelyverticutting and core aeration can not keepwith maintaining the current thatch levels,let alone reduce the amount of thatch and

organic build up taking place on top of abermudagrass athletic field.

INTRODUCTION TO FRAZE MOWING

In 1996, Ko Rodenburg decided thatthe practices of verticutting, core aeration,and topdressing for thatch and organicmanagement on his Kentucky bluegrassand rye fields needed another option. As

Concept to active practice: fraze mowing bermudagrass makes debut

With overseeding andfeeding the fields, thegrass could regeneratequickly, nearly thatchand organic free.

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the parks superintendent for Rotterdam,Netherlands, Rodenburg created a machinethat could remove 100% of the thatch andorganic build up that accumulated each sea-son. At the same time, the machine re-moved the poa annua plants and seedaccumulation while leaving the crown ofthe Kentucky bluegrass and rye grass for re-generation. With overseeding and feedingthe fields, the grass could regeneratequickly, nearly thatch and organic free. Ro-denburg’s fields immediately becamestronger and more durable as the re-growthof the stand was much hardier than theoriginal sword of grass. Additionally, thecompaction potential at the surface was re-duced because the fines from the organicbuild up were cleaned out and the diseasepressure was nearly eliminated with thethatch removal of the thatch. Thus in 1997,fraze mowing with the KORO Field Top-maker was born.

The adaptation of fraze mowing tobermudagrass is more an introduction ofthe entire concept to the United States. A

practice common on fields across Europe toimprove field durability and reduce poaannua, fraze mowing fits naturally intobermudagrass thatch and organic manage-ment. That adaptation became even morenatural this year with the introduction ofthe Universe rotor for the KORO FieldTopmaker. The Universe, designed byImants (makers of KORO) and CampeyTurf Care (of Manchester, UK), is for frazemowing Desso sand-based natural grassfields. The 3/8” blades, aligned on four spi-rals, allow for Desso fields to be frazemowed without damaging or pulling outthe synthetic fibers in the sand. The smallteeth do the same for bermudagrass plants,cleaning off the stolons, thatch, organicbuild up, and leaving the rhizomes of thebermuda exposed in order to regeneratequickly.

Allen Reid and Miles Studhalter at FCDallas Park became the first Americans tocommit to fraze mowing entire fields (frazewhen referencing bermudagrass) to cleanout ryegrass overseeding, thatch, and or-

ganic build up on three fields. In mid-March, Simon Gumbril from Campey TurfCare was on hand in Dallas to oversee theprocess. Also, Joe Pemberton, headgroundsman at Manchester United’s Car-rington Training Ground stopped in to FCDallas Park to observe while in the USA ona vacation.

The 419 bermudagrass was still 95%dormant in March, but a few of the rhi-zomes were showing some green in thefields as they were cleaned off. See photo 1-6 for the results.

The highlight field, the FC Dallas train-ing field, was out of play for 8 weeks,though the field was ready for play in 7weeks. The unseasonably cold spring in theDallas area hampered the re-growth byslowing the 419 bermuda’s exit from dor-mancy, extending the re-generation periodby approximately 2 weeks. But still, theprocess succeeded. According to Reed, “Thefirst day Coach walked back on the pitch hesaid, ‘the field feels strong.’ Now after 2months of daily training, the field has been

Left: Fraze mowing process Middle: Rhizomes exposed after rye, thatch, and organic removal Right Top: First mowing, 2 weeks after fraze mowingRight Bottom: Field 6 weeks after fraze mowing

28 SportsTurf | August 2013 www.sportsturfonline.com

FieldScience

lightly verticut one time to stay ahead of thethatch, and is showing little to no wear.”

Fraze mowing next used when MarylandSoccerPlex Grounds staff cleaned off threefields of Patriot bermudagrass in early June.Because the fields were sprigged only 18months ago, the processes was intended totransition out the ryegrass and promote aquicker transition to full bermudagrass in-stead of cleaning out years of thatch and or-ganic build up. The Patriot bermudagrasswas 30% out of dormancy when cleanedoff, but within 10 days all of the exposedrhizomes were green and responding. A lackof warm weather was again an obstacle forthe SoccerPlex fields, but not to the extentof Dallas. See photos 7-9 for results.

The three SoccerPlex fields that werecleaned off were 100% bermudagrass im-mediately. The non-fraze mowed bermuda-grass fields still were only 80% bermuda(rye being the other 25%) on July 1. Addi-tionally, the removal of only a thin layer oforganic build up on top of the native soilfields now allows water to be absorbed intothe soil faster. Following heavy rains, thefraze mowed fields now soaking in rainmuch faster than before, allow the fields tobe used more.

Also in June, a golf course fairway ofCelebration bermudagrass in North Car-olina was fraze mowed to demonstrate theprocess on active, fully growing bermuda-grass. The Celebration had begun to buildup a thick thatch layer that needed cleanedout (see photos 10-12).

Fraze mowing is a new process to theUnited States turfgrass market. Yet manyintuitive sports turf managers have always

1.THATCH/ORGANIC build-up, June 20122.THATCH/ORGANIC build-up, July 2013 (re-duced by 1 inch)3.FRAZE MOWING Patriot bermudagrass 4.GREEN RHIZOMES prepared to re-generatefrom Celebration bermuda5.GREEN RHIZOMES exposed from fraze mow-ing 6.THATCH BUILD-UP removed from Celebrationbermudagrass7.EXPOSED RHIZOMES following clean out viafraze mowing

1.

2.

3.

4. 5.

6. 7.

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used similar techniques such as scalping, shallow sod cut-ting, and even burning off to remove thatch build-ups.Now those are brought into one practice. The process is avastly different approach to thatch management. It is apractice is not for the faint of heart and can leave a sportsturf manager questioning whether they should have done itor not for the 1st week. But ultimately, the strong grass willprevail.

Albert Einstein said it best: “If you always do what youhave always done, you will always get what you have alwaysgot.” Can fraze mowing bermudagrass become an acceptedpractice in a regular maintenance program to advance thedurability of fields for them to sustain more traffic? That isnow up to the industry to decide. For more on fraze mow-ing bermudagrass, see Jerad Minnick’s blog, http://Grow-ingGreenGrass.Net. n

Jerad Minnick is sports turf manager of the Maryland Soc-cerPlex at the Maryland Soccer Foundation, Boyds, MD. AllenReed is stadium groundsman for FC Dallas.

FIELD 12 following fraze mowing compared to 5 weeks later

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