Spring is in the air! I love seeing the trees bud out and the lawns green up, and I’m enjoying the nice weather. Unfortunately, this beautiful spring weather has created perfect conditions for large patch in our St. Augustine grass and zoysia grass.
Rhizoctonia solani is a fungus that is present in the soil year-round, but it takes advantage of cool temperatures and wet soil to cause a turfgrass disease known as large patch (sometimes referred to as brown patch in cool-season grasses. The first symptom of large patch is circular, discolored patches in the turf. An easy way to diagnose large patch is to pull on the grass blade or shoot. A diseased shoot will pull out very easily and will have a dark brown lesion that looks a little rotten.
I have good news and bad news about large patch in the spring. The good news is that grass will recover from light disease symptoms as the temperatures rise in the late spring, and new growth should fill in during the summer. In fact, Texas A&M AgriLife turf specialists say that treatment is not cost-effective in the spring because the warm temperatures will take care of the disease for now. If there was extensive crown and root damage, however, you might need to put down new sod in the damaged areas. The bad news is that large patch is hard to get rid of and will probably come back in the fall. You need to be prepared to treat with a fungicide in the early fall to control large patch.
Large patch thrives in lawns that have poor drainage and are over-fertilized. Good lawn management can help avoid outbreaks of large patch. A few tips for lawn management:
- Improve drainage in your lawn, and only water when necessary.
- Mow regularly at appropriate heights. St. Augustine should be mowed at 2-3 inches, and zoysia should be mowed at 1-2 inches.
- Do not over-fertilize. Fertilize three weeks after spring green-up. Our grass is just starting to really green-up, so wait until the end of April to fertilize.
