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How much bermudagrass is enough bermudagrass for adequate spring recovery? Mike Goatley, Professor and Extension Turfgrass Specialist, Virginia Tech
Figure 1. A mature Patriot bermudagrass turf that is slowly emerging from dormancy following an extreme winter.
Following one of the most challenging winters in the past 25 years in Virginia, many bermudagrass stands look very much like that in Figure 1. So far, while there has been some turf loss in the state due to ‘winterkill’, the damage is not nearly as catastrophic as many of us predicted given the extremes of this winter. The Virginia Tech NTEP Bermudagrass trial has several completely dead plots, and there is no doubt that summer 2013 plantings were more likely to be damaged than mature turf areas. Spring Dead Spot is certainly very prominent this year, and I strongly suspect that is in direct correlation to the severity of the winter. But as the grass emerges from dormancy, a common question is “How much bermudagrass regrowth potential is required to meet the needs for the next growing season?” That is a great question for which Virginia Turf does not have a definitive answer, but let’s make some educated guesses and/or some other points for you to ponder and to possibly enact. And if you implement these or other strategies, please share your findings so that everyone else knows what has been attempted. Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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I have always been a proponent of the concept of “one living plant per square foot” is generally enough bermudagrass to manage back to a completely covered canopy during the growing season. However, what if you are in the mountains of southwest Virginia and you are wondering if your bermudagrass growing season is going to be a repeat of 2013? For that reason, I think that VT Sports Turf Manager Emerson Pulliam and team’s decision to sod Worsham Field from hash to hash makes perfect sense to me given the anticipated use of that field for practice and its early season schedule for 2014. The recover from “one living plant per square foot” is certainly easier to achieve with an ultra‐ aggressive variety like Patriot (Figure 1), and probably requires a great deal more patience with a slower growing variety like Tifsport. In my opinion, the bermudagrass in the photo represents a stand, that while damaged from the winter, has sufficient growth potential to fully cover with an appropriately aggressive N fertility, irrigation, and mowing program IF this is not a heavily trafficked turf. There is no doubt that if this grass is under heavy use on an athletic field or is a primary fairway entry/exit point for foot traffic or golf carts that its coverage rate will be affected. However, in most situations statewide (and especially from Richmond to Southside to Tidewater), I would not be very worried about a stand density similar to that pictured and its ability to spread over a period of a few weeks with the arrival of hot weather and enough N fertilization and water to promote lateral spread. One regular challenge for bermudagrass in transition zone spring seasons relates to whether or not it is overseeded – how much bermudagrass is there underneath overseeded perennial ryegrass stands? I have been pleasantly surprised that in three aggressively overseeded stands of bermudagrass that I have seen since the beginning of May (Patriot bermudagrass at Louisa Co. High School; Latitude 36 bermudagrass at Scott Stadium, UVa; and Vamont bermudagrass at Farmington Golf Club in Charlottesville), that each of them had fairly significant stands of bermudagrass in place. A worry that I had that I hope does not come to fruition is that the bermudagrass would be very weak coming out of dormancy in 2014 given that it was such a poor year for bermudagrass growth for most of 2013 (very cool, wet, and cloudy for much of the year). I encourage everyone not to get too greedy regarding enjoying the beauty and playability of the ryegrass if it is your goal to restore the bermudagrass canopy. While it is certainly variety dependent, I still find Dr. Fred Yelverton’s (NC State Turfgrass Weed Scientist) comment I heard at a conference a few years ago that “in general, bermudagrass needs 100 days of good, competition‐free weather” to be a pretty good measuring stick for planning purposes. Our bevy of outstanding sulfonylurea herbicides have revolutionized our ability to safely transition ryegrass out of bermudagrass stands. Several turf managers and I have been bouncing around ideas about other ways to really see what one has for bermudagrass regrowth potential and/or to get it going this spring. One of Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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the best, most rapid ways I have found to assess how much bermuda might be lurking in a currently thin stand of grass is to heat it up by placing a piece of vented clear plastic over the area. When I have done this on a larger scale I simply bought a roll of clear plastic on the roll and vented it with a drill bit on 4‐6” spacings. Tack it down with some sod stapes and in a couple of days you should have your answer about how much regrowth potential there is in the sod. I also have a strong suspicion that in winters like 2013‐14 that there might actually be regrowth potential below ground (rhizomes) that just never makes it to the surface because there isn’t enough energy in these stems to penetrate the dense canopy of dead stems and leaves on the surface. I saw a situation that supports this possibility during my tenure at Mississippi State when someone had taken a tractor‐mounted box blade and scraped the surface off of some common bermudagrass areas on campus in order to smooth the soil surface following some utility work. Later on that spring, those scraped soils were 100% green common bermudagrass, and anything surrounding them that was not scraped was completely dead. My buddy Dr. Jeff Krans and I debated this back and forth about what could be going on and the exposure of these previously buried stems was the only answer we could come up with that explained such drastic differences in grass survival and death. I think the scraping scenario fits in well with the current trend and interest in fraze mowing and its benefits too. Now, can you achieve this same effect with a vertical mower? Maybe, but I am not sure; just as with the box blade, it all depends on how aggressive one gets. Would the possible disruption of stems by the vertical mowing blades offset the benefits of getting rid of some of that mat? One thing I do feel is beneficial in almost any case where one is trying to ascertain just how much grass is present is to ‘scalp and scratch’ that dormant/dead bermudagrass surface to try to get rid of as much of that debris as possible. Finally, another pretty easy way to get some heat into the mix is to use something that darkens the surface. Perhaps that can be a light application of compost or even easier, a colorant application to the area. While a colorant won’t be as long lasting of a treatment as a paint, it requires no special sprayers or pumps to put out a little color to absorb some radiant energy. When your spring sport’s seasons are over, don’t forget that there is often value of getting rid of a lot of that biomass on your bermudagrass turf (I know it is what you have worked so hard to achieve… but remember that there can be too much of a good thing) if you have been complaining about its previous late summer/fall mowing quality. I tell people to “build bermudagrass from the ground up” when use and schedule allow. One of the best examples of how our latest generations of ultra‐dense bermudagrasses can get away from us over the years when the shoot density of the grass actually becomes a concern for field quality is shown in Figures 2 and 3. These photos were taken in late August 2012 on a Lynchburg, Va Patriot bermudagrass football field. In Figure 1, the great looking grass on the sidelines on the left was Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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described as being almost worn down to the dirt by the end of the spring 2012 soccer season from all the traffic from fall and spring sports, but after it filled in during the summer, this sideline area by August is now the highest quality, best looking grass on the field. The reason for the difference in appearance is what is going on in the canopy architecture between the two locations. Figure 2 shows the bermudagrass sprig on the left to be a much more juvenile plant that has multiple leaves up and down the stem from the season’s new growth that came back from the traffic‐exposed stems. The bermudagrass sprig on the right is a much more mature plant that primarily has a few leaves on the top and a lot of stem material in the canopy. It has very poor mowing quality because there simply is not a lot of green leaf tissue to mow. It is prone to scalping and there really is not a lot that can be done in the fall to restore the turf’s juvenility (and its number of leaves). The grass is literally shading itself out and we know how poorly bermudagrass performs in the shade. At some point this top material needs to be removed. Building the grass from the ground up takes some effort but I have seen it done successfully essentially by scalping the field after the bermuda was actively growing (and use allows) and blowing/sweeping and removing all that debris from the surface. For those with suitable budgets and labor, this canopy architecture is effectively managed by regular topdressing and/or vertical mowing, but these practices are not always possible for golf or sports turf facilities that don’t have the necessary equipment or dollars to spend. There also can be benefits in taking advantage of the growth modification activity of plant growth regulators in conjunction with regular topdressing and vertical mowing.
Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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Figure 2. Note the difference in mowing quality of Patriot bermudagrass that received significant traffic on the sidelines versus the less trafficked turf on the playing surface.
Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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Figure 3. There is a large difference in the number of green leaves from the more juvenile stems from the sideline (left) and the more mature stems from the center of the field (right).
I hope this helps in making some decisions regarding this spring’s bermudagrass recovery programs. Again, please let us know your observations and findings regarding your spring management strategies.
Disclaimer: This information is for educational purposes only. Any commercial products named in this publication are for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. Virginia Cooperative Extension programs and employment are open to all, regardless of race, color, s national origin, sex, religion, age, disability, political beliefs, sexual orientation, genetic information, marital, family, or veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer.
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