Ultra dwarf bermuda greens is a popular choice for greens conversion in Texas, what is the problem?

Recently it has become popular for courses in locations such as Dallas / Fort Worth, Texas to renovate greens by removing bentgrass and replacing them with an ultra dwarf variety of bermudagrass (i.e., Mini-Verde, Champion, or Tifeagle).

The reasoning for this is the summer performance of bermuda compared to bentgrass.  Comments include, no more fans, no more soft greens in summer and everything will be better.

What is the elephant in the room with this reasoning in a transition climate such as Dallas / Fort Worth Texas? 

1. Potential extensive winter kill of bermuda greens creating a disaster for spring / summer recovery. 

2. Poor shade tolerance of the ultra dwarf bermudagrasses may require extensive tree removal.  Bermudagrass greens requires 6 to 8 hours of direct sunlight, reaching all parts of a green, during all seasons.

3. Poor winter traffic tolerance of bermudagrass.  During winter months bermuda greens in Dallas / Fort Worth may show wear from foot traffic in walk on and walk off portions of each green.  This would necessitate resodding of some walk on walk off areas of greens in the spring months, as a result of winter foot traffic damage.

Severe winterkill potential is the elephant in the room!

Mini-Verdi, Champion and Tifeagle are subject to winterkill with temperatures below 21 degrees F.  Extensive published university research at Texas, Arkansas, Kansas, Missouri, North Carolina, Florida, and Clemson reports these ultradwarf varieties of bermudagrass are not the most cold tolerant and are subject to winterkill, spring dead spot, and slow spring green up.

Records for the Dallas / Fort Worth 100 year winter low temperatures show 28% of the time the low was 10 degrees F or lower. 

In the last 30 years there were six years with lows of 10 degrees F or lower.

The Christmas week of 1983 in Dallas / Fort Worth is notable with 295 hours (11 1/2 days) straight with temperatures of 32 degrees or less. 

1983 stands out: Dec 21 record low of 10, Dec 23 record low of 19, Dec 24 record low of 7 and a high of 13, Dec 25 low of 6 and a high of 18, Dec 26 record low of 16, Dec 27 record low of 31, Dec 29 record low of 10, Dec 30 record low of 7.  All of this provided 295 consecutive hours at or below freezing: 7am Dec 18 to 2pm Dec 30, 1983.

When there is a repeat of this kind of cold snap there is 100% certainty that Mini-Verde, Champion, Tifeagle greens will be 100% winterkilled.  Yes, the potential for totally dead greens in the spring.

Covering greens with a plastic cover during this type of winter cold spell will not save the untradwarf bermuda greens from a weather event such as that described above.

Dallas / Fort Worth Texas:  Keep Bentgrass Greens or Covert to Bermudagrass?

Bentgrass greens

Positives:

1. Most desired putting surface from September though June.

2. Most dependable putting surface for spring and early summer tournaments.

3. Members know what to expect with bentgrass greens.

4. Less surface grain that may affect putting compared to ultra dwarf bermudagrass.

5. Bentgrass is extremely cold tolerant.

6. There are now more heat tolerant varieties of bentgrass available compared to the "A" varieties (i.e., 007 and Tyee bents are more improved compared to older varieties).

007 greens have endured five summers of extensive heat and drought at the Wichita Falls Golf Club and three year old Tyee greens have permormed exceptionally well at Preston Trail Golf Club in Dallas.

Negatives:

1. Must be carefully managed during the summer heat stress period of July and August.

2. May experience soft greens during the summer heat stress period.

3. Use of fans around greens to improve air circulaton may be necessary.

Ultra dwarf bermudagrass greens

Positives:

1. Most desired putting surface from June through November.

2. More heat tolerant compared to bentgrass.

Negatives:

1. Questionable winter cold tolerance, winterkill may occur during low temperature events - near or below 10 degrees F.

2. Requires 6 to 8 hours of direct sunlight each day, year around.

3. Plastic mesh covers applied on greens during cold weather spells  requires significant labor.

4. Will change how the course plays for the average golfer - harder to hold a mid iron or rescue club, as the greens will be firmer.

5. Ultra dwarfs produce more surface grain compared to bentgrass greens, which affects putting.

6. Not summer maintenance free as some have promoted. Weekly summer brushing, grooming, and light sand topdressing required to keep thatch under control.