Flooding of turf
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Recent heavy rainfall events and subsequent flooding of turfgrass areas caused me to dig into the files and revisit some information on turfgrass survival following flood events. Turf survival following floods depends on several factors including: turfgrass species, submergence duration, submergence depth, water temperature and light intensity.
Turfgrass species differ in what they can tolerate when it comes to surviving submergence. Unfortunately, there are no hard fast numbers. Kentucky bluegrass will survive 35 days and creeping bentgrass 38 days. Instead, they are given relative tolerance ratings (these ratings are from what we in the profession affectionately refer to as the “Turf Bible” – Dr. Jim Beard’s, Turfgrass Science & Culture). Relative submersion tolerance: creeping bentgrass – excellent, Kentucky bluegrass – medium, Poa annua and perennial ryegrass – fair.
Submergence duration is going to relate closely to turf species when we consider its impact on survival. For example, if you have Poa annua that is submerged for several weeks it would seem that its ability to survive will probably be less than that of creeping bentgrass.
As submergence depth increases, the potential for injury increases. Just think of it this way, if the leaf tissue is above the water line, even just a little bit, the turf will probably survive. Ever seen creeping bentgrass floating on the edge and even growing out into a lake on a golf course? That’s a perfect example of turf surviving when partially submerged.
That brings us to the final two factors affecting survival, water temperature and light intensity. Here are two factors that work in our favor in the spring as the air and water temperatures have been cool. Combine that with cloudy conditions and turf has a much better shot at making it through than if this flood was in August.
As the water recedes, you’ll likely notice that the turf may be yellow or brown. This will even be the case in areas that not flooded but where the soils were saturated. What is happening here is the turf has lost its ability to take up nutrients. It doesn’t take long once turf is submerged for soil oxygen levels to decline and root hairs to begin to die. As the turf’s root system becomes impaired, nutrient extraction and water uptake will be limited. Keep this in mind once the water has receded as the turf may benefit from a light fertilizer application.
To assess whether or not submersion has caused injury, it would be a good idea to extract several plants from around the site and cut a horizontal cross section through the crown. If the crown is white and firm, it has survived. If the crown is brown and mushy, it’s dead; so think about your reestablishment plan.
Finally, for those areas that were flooded due to a creek, stream, or river overflowing a bank, you are probably dealing with silt or soil deposition on the course. Removal of soil deposition can be challenging, but do what you can and keep in mind that once soil conditions are dry enough to allow it, soil cultivation, whether it’s core aeration or slicing, you’re going to want to break through that layer of deposited soil to facilitate rooting and water infiltration.
Dr. Frank’s work is funded in part by MSU‘s AgBioResearch.