Overseeding bermudagrass with perennial ryegrass often results in thin or bare areas after the ryegrass dies the following summer. These thin or bare areas typically will require six to eight weeks – or more – to recover in July and August. Sometimes the damage is widespread, and sodding is needed to reestablish the bermudagrass prior to overseeding again in the fall.
Historically, aggressive cultural practices such as vertical mowing or aeration are omitted in the thin areas to avoid severing stolons in hopes they will “tack down.” The thought is that severing the aboveground stolons would hamper recovery. However, from time to time we learn a great deal from “happy mistakes.”
During one course visit this year, several very thin areas were fraze mowed to prepare for sodding. Unforeseen circumstances did not allow the course to sod these areas and, lo and behold, in a period of two to three weeks the bermudagrass had recovered faster in the fraze mowed areas than adjacent thin areas that had not been fraze mowed. Removing the thick organic layer in the top 3/4 inch of the soil exposed underground rhizomes and stems and expedited growth and recovery.
Results from the aggressive fraze mowing practice were shared with other courses facing similar weak areas during subsequent course visits. Several superintendents have since reported enhanced bermudagrass recovery and density through fraze mowing, flail mowing or aggressive vertical mowing in thin areas.
It’s already early September and time is running out to heal thin or bare bermudagrass areas prior to overseeding. Rather than throwing fertilizer at these areas and waiting for recovery, conduct aggressive thatch reduction practices to encourage new bermudagrass growth. The thatch and organic matter reduction will also help with fall overseeding.
When you observe thin or bare bermudagrass areas next summer during the transition process, consider a more aggressive thatch and organic matter reduction or elimination process to expedite bermudagrass growth rather than relying on fertilizer and spot watering.
West Region Agronomists:
Brian Whitlark, senior consulting agronomist – bwhitlark@usga.org
Cory Isom, agronomist – cisom@usga.org