Spring has sprung in the southeastern US, and severe cases of spring dead spot have been reported throughout the region. The relatively severe winter is likely to blame, as cold temperatures tend to bring out spring dead spot symptoms.
The frustrating thing about spring dead spot is that the damage is done and the disease cannot be controlled once the symptoms appear. However, there are several things that can be done NOW in preparation for next year:
1. Consider converting severely affected areas to a cold-tolerant bermudagrass variety. Varieties of bermudagrass that have been bred for cold-tolerance, like Patriot, Yukon, and Tifsport, are affected by spring dead spot less severely. They still get the disease, but patches are generally smaller and recovery is quicker. This simple solution can save a lot of time and money in the long term.
2. Map severely affected areas for fall fungicide applications. Spring dead spot fungicides, like Rubigan, are very expensive. You can save a lot of money and avoid unnecessary fungicide use by only treating the affected areas.
3. Avoid the use of DNA herbicides for annual grass control. Some crabgrass herbicides reduce bermudagrass root growth and can slow recovery from spring dead spot. Use a pre-emergence herbicide like oxadiazon, which does not have this effect.
4. Aerify and/or spike severely affected areas every two weeks. Breaking up the layer of dead turf and thatch will help the bermudagrass to spread into the patch more quickly.
5. Choose your nitrogen carefully. The type of nitrogen you apply can have a major effect on spring dead spot development. We have traditionally recommended ammonium sulfate to suppress spring dead spot, but our recent research is providing some interesting results. After 4 years of applications, ammonium sulfate is only suppressing spring dead spot caused by Ophiosphaerella herpotricha and is having NO EFFECT on O. korrae. Calcium nitrate, on the other hand, is doing an excellent job of controlling spring dead spot caused by O. korrae, but is having no effect on O. herpotricha. Stay tuned for updates on this research.