With soil temperatures across much of North Carolina finally starting to creep down, it is that time of year for turfgrass managers to start thinking about making preventative fungicide applications for two very common diseases of warm-season turfgrasses (spring dead spot and large patch). To monitor these temperatures, please visit the State Climate Office of North Carolina by clicking here and choose average soil temperature from the drop down menu.
Spring Dead Spot Info
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 or soon will be and you can bet it’s infecting your bermuda and zoysia grass plants as I type this post. We know through years of research that fungicides are most effective when applied while the soil temperature is between 60 – 80°F in the fall of the year.
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 should run 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.
To learn more about spring dead spot please click here.
Large Patch Info
Large patch, which is caused by the fungus Rhizoctonia solani, is a common disease of centipedegrass, St. Augustinegrass, zoysiagrass, and bermudagrass grown for lawns, landscapes, golf turf, and athletic fields. Centipedegrass and St. Augustinegrass are particularly susceptible to severe damage from this disease.
Fungicides are available for large patch control, but they must be applied preventatively for best results. The first application should be made in the late summer or early fall when average daily soil temperatures are 70°F or below.
One fungicide application will control minor cases of large patch, but two to three applications on a 4 to 6 week interval may be needed to control severe cases. Fungicides are not very effective once the symptoms of large patch appear. Curative applications will help to reduce further spread of the disease, but the affected turf will be very slow to recover.
For more information about Large Patch please click here.