Sports turf tips
r e t n i W t s a L h s r a H s a WLet’s Prepare for the” e —
n O g i B “ Next
By Barry Stewart, Ph.D., Associate Professor, Mississippi State University
One
thing the severe winter of 2013–2014 did was that it identified areas of turf that were weak going into winter. Areas that were damaged by traffic or suffered from poor drainage or shade issues were some of the areas that recovered most slowly this spring or experienced turf loss. Even many sod producers noticed that their harvested field areas that did not recover were cut earlier in the year than normal. For example, sod cut as early as July suffered winter injury where, in a more normal winter, the cut-off harvest date for winter injury in bermudagrass may have been in August. I hope that your sports turf has recovered from the winter and that you are heading into the fall playing season with a full turfgrass canopy. In this space, I would like discuss what we can do to assure that we will lose minimal amounts of turf when we experience another severe winter.
Fertilization
First, I hope you have a recent soil test that you can work from or have been working from. Soil testing is one of the best investments you can make in your field. With the exception of some fall adjustments for N and K application, I would follow the test-result recommendations, as they will ensure that your soil fertility is in an optimal (or at least adequate) state with respect to bermudagrass. 20 • Mississippi Turfgrass • Summer 2014
Some soil tests do not typically call for N application after August 15, but I recommend another application of N late in the season. One school of thought is that late-season N application leads to succulent growth and leaves the bermudagrass susceptible to winterkill, but research at Mississippi State in the late 1980s and work done at numerous other locations have proven that this is not actually the case. Furthermore, bermudagrass that received late-season N was found to green up more quickly the following spring. Some potassium (K) should also be applied with this N unless soil test levels are already in the high range of the soil test. The uptake of N will stimulate growth and a simultaneous and subsequent uptake of K. The K will act as a stress fighter and will allow the grass to go into dormancy and greenup with less stress. It is interesting to try to locate the origin of the concept of not feeding our grass after August 15. Late-season N applications in some of our other warmseason grasses, including centipedegrass and St. Augustinegrass, can be detrimental due to incidence of brown patch disease. Perhaps someone once made a blanket recommendation to all warmseason turf, and it stuck. Another possibility is that the August 15 cutoff came from home lawns that do not receive the traffic that athletic fields do. Keeping the turf growing and succulent
in the fall can lead to insect infestations and disease concerns, and this might be a reason not to fertilize a home lawn. Late-season N applications are not practiced in forage bermudagrasses, so that is another possibility. An athletic field that is still receiving traffic, however, needs fertility to recover. Rapid recovery outweighs the risks of disease and insects that can be controlled when they occur. Depending on soil type and field expectations, I would recommend applying 2 to 4 lbs. of N per 1,000 ft2 approximately 9 or 10 weeks before the average first killing frost. Clayey fields or fields with less traffic would be on the lower end of this, and sandy fields or fields with heavy traffic would be on the high end. In Starkville, the first killing frost is usually about November 6, so this last N application would come in the last week of September. For this application, my recommendation would be for a product that is 50% soluble N and 50% waterinsoluble N. This should allow for even growth throughout the end of the season. If your soil test calls for K, apply an amount one half of what you applied in N. For example, if you applied 3 lbs. of N, then apply 1.5 lbs. of actual K. This application will take the turf through the end of the season and allow it to go into the spring with increased carbohydrate reserves for spring greenup. In most years, we