Four new Spring Dead Spots after a relatively mild winter.
So your warm season grass is scalped down and it’s starting to green up. At first, it has a nice uniform look. After a few days of warm Spring weather, as the grass greens up, you start to see the dreaded Spring Dead Spots (SDS).
While SDS is most prominent in Bermuda grass, it can also affect Zoysia grass. SDS is caused by three hard to pronounce fungi. The thing to know is that the fungi doesn’t kill the grass; it weakens the roots which is then too weak to survive Winter’s cold temperatures.
I saw this in action a few years back. We had a Winter where temps didn’t get low enough to put my yard into full dormancy. To my delight, when Spring came, all my SDS was gone. At the time, I thought it was gone for good as the warm Winter killed the fungi. The next Spring, after a normal Winter, the SDS was back. That is when I learned that the cold does the killing not the fungi.
There isn’t any easy way to control SDS. Ironically, this may be the one time when the grass is greener on my neighbor's yard, because yards that are not maintained all that well usually don’t have SDS. Some of this could be due to mowing heights and fertilization. The higher you mow the deeper the roots grow, and fertilization causes the PH in your yard to increase.
Aerification is one of the areas where I can improve. Roots need oxygen to be healthy. The one thing that holds me back is not having a truck to haul an airiator. However, this year I’m committing to doing whatever it takes to aerate. You may have someone knock on your door offering to aerate for you. Usually, these services are going to go over your yard once. Once isn’t enough. To be effective, you’ll need to have 10 holes per square foot. That means you need to go over your yard several times. June is a great time to aerate. Late Summer early Fall isn’t a good time as it doesn’t give the roots time to adjust before Winter.
I’ve heard that in North Georgia some have seen success in reducing SDS by using calcium nitrate fertilizer. I mentioned before that there are three fungi that cause SDS. The one most prominent in North Georgia seems to be sensitive to calcium nitrate. For more on this, take a look at page 26 of this study. Yara has a yard calcium nitrate fertilizer. I’ve gone as far as tracking down the Yara Rep for the Southeast but unable to find a distributor in the area that carries the product. If you find it, try it and if works, let me know.
Once you have SDS, there are three ways you can repair it. The first and easiest is to let the Bermuda grass repair itself. This could take until late June. The second option is to replace the grass with sod from Super-Sod. (Okay, that was a shameless plug. Please forgive me.) The third is more work but will repair the spot for years. That is to dig up the spot. Go deep enough, 12 inches, to remove the fungi. Replace the soil with new topsoil and then the grass.
I’ve done all three. The one I like best is to replace the sod. A few years back I did dig up the SDS and replace the topsoil. I didn't get all the fungi on two locations in the back. Take a look at what I have now. The problem with the front yard is that I did get rid of the spots but now have several more just two years later. I won't be digging up SDS anytime soon.
Now I have SDR. Instead of two small spots, I now have a large Spring Dead Ring. Looks like a pair of glasses....
Best practices to reduce SDS is to aerate, grow your turf higher for deeper root growth and don’t add nitrogen 30 days before the average first frost.