Non-overseeded ultradwarf bermudagrass greens

By Brian Whitlark, USGA Green Section

In the desert Southwest, eliminating overseeding on ultradwarf bermudagrass greens is rapidly becoming the new trend, partially due to poor bermudagrass recovery after overseeding, but mostly because golfers have discovered that non-overseeded greens offer better surfaces for more golfing days.

In the fall, when many overseeded greens are slow, wet, and prone to pitch marks, ultradwarf greens are at their best. When the overseeded turf is weakening the following summer and ball roll becomes inconsistent, non-overseeded greens often perform far better. However, there are more than a few misconceptions with respect to non-overseeded greens, both from an agronomic and playability perspective, that need be addressed before we move on and discuss specific management strategies.

As a few leading turf managers have already discovered, managing non-overseeded greens in the winter can be tricky, and there are a number of pitfalls that must be avoided. Several misconceptions and pitfalls are summarized in the following points.

Misconception: Greens Firmness. In informal surveys, most golfers, golf professionals, and even most turf managers perceive that non-overseeded greens are firmer and therefore less receptive to golf shots than overseeded surfaces. This is simply not true. In fact, in every case where this author has quantified the firmness using the USGA TruFirm on both overseeded and non-overseeded surfaces on the same green, the non-overseeded portion is always less firm. Most likely, the non-overseeded surface is softer, a result of more thatch mat, which leads us to the next bullet point.

Misconception: The practice of overseeding greens creates more thatch and organic matter than when not overseeded — true or false? Based on personal observations, it appears this statement is false. Although there is no research data to confirm this, experience with measuring thatch and organic matter levels on both non-overseeded and overseeded greens shows that the non-overseeded surfaces always produce more thatch, at least in the desert Southwest. The bermudagrass grows for more days without competition from the cool season turf and therefore produces a greater thatch mat.

Misconception: Traffic Damage. Course officials often express that their primary fear with non-overseeding is the damage from traffic, the potential for weak turf, and even bare ground. This is not the case. One golf property that regularly sees more than 60,000 rounds per year (80 percent between November and May) had no issues with traffic damage on non-overseeded ultradwarf surfaces.

Misconception: Ball Marks. Given that non-overseeded greens are likely softer than their overseeded counterparts, one would assume that ball marks will be more prevalent. However, this has not been the case. In fact, all the turf managers that contributed to this article were in agreement that complaints about ball marks were nonexistent or decreased substantially once overseeding was eliminated from the greens program.

Pitfall: Winter color. Right or wrong, the desert Southwest market demands green. This should not be a deterrent to eliminating overseeding from the program; it is merely an additional challenge the turf manager must address. Turf colorant technology has come a long way in recent years, and superintendents are now offering cosmetically attractive, non-overseeded greens in the dead of winter. Several turf managers offer their colorant strategies later in this article.

Pitfall: Green speed. One very real concern in the desert Southwest is excessively fast green speeds during extended periods of cold weather and negligible growth. However, with a sound fall setup program, green speed can be maintained at an acceptable pace throughout the winter. Fall is the time to increase mowing heights and reduce mowing frequency. When growth stops in December or January, it is likely too late to increase heights.

Pitfall: Scarred hole plugs. Another concern when not overseeding greens is that old hole plugs recover slowly. If plugs are high and scalped, recovery will be slow, although colorants often hide such scars fairly well. Furthermore, if thatch is not aggressively controlled throughout the year, the turf around the outside edge of the hole plug often deteriorates in a half-moon pattern, forming a scar. This issue is seen throughout the year where horizontal stolons are allowed to grow unabated, but this is most problematic in the winter. Unfortunately, if hole scars are an issue at your course, substantial improvement will likely require several years of more aggressive surface grooming practices.

After reading the above-mentioned summary, the primary fears about not overseeding greens should have been addressed. Turf managers should take note of the pitfalls mentioned, including winter color, green speed, and scarred hole plugs. With this in mind, the remainder of this article will focus on strategies that three turf managers have employed in the Southwest Region to overcome such pitfalls and endear golfers to non-overseeded ultradwarf greens.

Fall, which for the sake of this article includes October, November, and a few weeks into December, is an important setup period for preparing for the onset of winter dormancy. The fall months are essential to encourage late-­season growth, increase heights, employ what are likely the last surface grooming practices for the year, and begin using colorants.

How do you encourage late-season bermudagrass growth and color?

Charlie Costello, superintendent, Phoenix Country Club: We spray urea and/or calcium nitrate to supply about 0.10 lbs. of N/1000 ft 2 every 7-10 days. Green spray dye is applied year-round, which warms the surface in the fall and encourages growth. Primo applications continue on a biweekly schedule, although rates drop from 14 oz./acre/month during the growing season to as low as 3 oz./acre/month in the winter.

Rob Collins, superintendent, Paradise Valley Country Club: Nitrogen inputs are increased from weekly applications at 0.10 lbs. of N/1000 ft 2 to 0.25 lbs./1000 ft 2 beginning in October and continuing through the end of November. Rates drop to 0.10 to 0.15 lbs. N/1000 ft 2 during the winter. Green pigment applications begin sometime in mid-November when growth has slowed, but the turf remains green.

Bill Rupert, superintendent, Alta Mesa Country Club: Nitrogen is applied every two weeks at 0.10 lbs. of N/1000 ft 2 during the summer. Once the humidity decreases and growth slows, nitrogen inputs are increased to 0.20 lbs./1000 ft 2 on a biweekly schedule. Green spray dye applications begin in early to mid-November.