So, your first question may be "Why on Earth are you telling me to apply fungicides for a spring disease in the fall and for something that will not show up for another 6-7 months?!" The answer is simple. The causal fungus, Ophiosphaerella spp., is active RIGHT NOW and you can bet it's infecting your bermuda and zoysia grass plants as I type this alert. We know through years of research that fungicides are most effective when the soil temperatures are between 60 - 80 ° F in the fall of the year.
As you can see by the soil temperature map from 9/22/11, the time is right for preventative applications. However, choosing the right fungicide and applying at the right time will not result in acceptable levels of control if you do not apply them correctly. Spring dead spot infects below ground plant parts. With that being said, you must either water-in your fungicide applications IMMEDIATELY with 1/4" of irrigation or apply with a carrier volume of 5 gal/water/1,000 sq. ft. You need to be running your irrigation the moment the applicator is out of the way. Do not wait until the following evening or night with your routine irrigation schedule or else you may be severely disappointed come next spring when these grasses green back up.
Just recently we have made some fantastic discoveries with fertilizers in regards to controlling this disease without having to use fungicides at all! To learn more about this, please click here.
Also, if you haven't heard, Rubigan will be coming off the market in December of 2012. Rubigan is one of the better fungicides available for spring dead spot control. To learn more about this, click here.
To learn much more about spring dead spot, including control recommendations and images, please click here.