Golf course superintendents are in the midst of preparing the bermudagrass for overseeding right now in the desert southwest. The following summary points highlight the top 5 practices to avoid during overseeding preparations.
- Aggressive verticutting– Stolons may be severed when verticut blades are set at a depth below 0.125. When verticutting alone does not stand the turf up properly, try brushing after verticutting and follow with another mower pass or possibly a second light vertical mowing. Next summer, you will regret injuring stolons in the fall in quest of perfect seed-to-soil contact.
- Spray a growth regulator prior to raising heights – This practice results in tight, dense turf that will need excessive verticutting and scalping that otherwise would be unnecessary. Raise heights, then apply the growth regulator immediately prior to scalping.
- Excessive scalping – Avoid scalping in excess of 50% of the mowing height at overseeding. For example, if the fairway mowing height is 0.500 inches at overseeding, do not scalp any lower than 0.250 inches. With this in mind, it is always best to raise mowing heights several weeks prior to overseeding for more effective scalping. If you are like many superintendents this year, the bermudagrass may have just filled in prior to overseeding. If this is the case, do not scalp lower than 0.300 in.
- Apply excessive nitrogen rates immediately prior to overseeding – Nitrogen (N) applied in an effort to fill bare ground prior to overseeding, can create horizontal stolons that may fill in the voids, but these stolons will have little or no carbohydrates to store for winter. It is likely that these plants will not survive the winter. It is best to discontinue N inputs 3-4 weeks prior to overseeding.
- Heavy topdressing on greens following seeding – A “sand blanket” applied up to 3/16 of an inch may work well with Tifdwarf or Tifgreen 328 greens; however, lighter rates should be used on the ultradwarf bermudagrasses. Sand, applied at this depth on the ultradwarfs, places the crown of the overseeded turf too high in relation to the deeper bermudagrass stolons. As a result, the mat formed from cool season grasses will delay bermudagrass recovery the following year.
Source: Brian Whitlark, bwhitlark@usga.org
Dr. David Kopec, dkopec@ag.arizona.edu