Zoysia grass is one of the most loved warm-weather grasses. It makes a lush green turf that is tolerant to drought, high foot traffic, and minimal maintenance. However, like every good thing, it has a downside.
Common problems with Zoysia grass include; thatch buildup, insects like clinch bugs and grubs, and lawn diseases such as brow patch, rust, and leaf spot.
Zoysia Grass Problems and Fixes that Work
The following are common Zoysia grass problems and how to fix them:
1. Brown Patch (Rhizoctonia blight)
Also referred to as a yellow patch or large brown patch. It is a fungal infection that is common in warm-weather grasses that is caused by the fungus Rhizoctonia solani. The disease causes browning or grass yellowing in circular patches. Patches sizes can range from a few centimeters to several feet in diameter.
Rhizoctonia solani thrives in hot wet conditions, and it is likely to strike during hot, humid weather. Poor draining soil increases the risk as rainwater will stand on the lawn for longer. Overwatering will also increase the risk of brown patches.
The disease can clear on its own when the soil conditions improve. To prevent brown patches, do the following.
- Avoid overwatering – water only 1inch per week during the dry season.
- Improve your soil drainage – Use soil additives to improve drainage. Also, check if the lawn is suffering from soil compaction; if so, aerate the lawn. Soil compaction causes poor drainage.
- Treat with fungicide – if, even after doing the above, the disease is not cured, buy fungicide for the brown patches.
2. Thatch Build Up
Thatch build-up is a common lawn problem for grasses that spread via rhizomes. Thatch is a layer of dead and living plant matter that accumulates between the grass and the soil surface. Thatch builds up when the grass produces organic debris faster than it is broken down by microorganisms.
A little amount of thatch is beneficial to the lawn, but when it exceeds ½ an inch, it should be removed as it will cause the lawn to be susceptible to fungal diseases and insects. Extensive thatch build-up prevents air, nutrients, and water from reaching the roots causing more grass to die.
Causes of thatch build-up include the following:
- Overfeeding the lawn with nitrogen fertilizer causes it to grow aggressively.
- Excessive usage of fertilizer and herbicide kills microorganisms that help in breaking down organic matter. You should incorporate natural methods of controlling weeds and feeding the lawn, such as using compost and mulching and getting rid of weeds by pulling them out or using corn gluten and vinegar.
To remedy thatch buildup, dethatch the lawn twice a year during the growing season. Also, avoid feeding the lawn excessively with nitrogen fertilizer and only water 1 inch a week during the warm season and once in two weeks during the cold season.
3. Rust (Puccinia spp)
Lawn rust is a fungal infection that causes red and orange spots on grass blades. It is caused by Puccinia or Uromyces species. The fungus thrives in moist, cool, and shady areas, and planting zoysia on a shady lawn makes it susceptible to lawn rust.
To prevent lawn rust, plant the lawn in full sun and water with 1 inch every week. If your lawn is already infected, you can treat it with a quick-release nitrogen fertilizer or use a fungicide meant to treat the disease.
4. Leaf Spot (drechslera, bipolaris, exserohilum)
The disease is characterized by brown or black spots on grass blades. The spots will grow large, killing the blades. The disease normally occurs during warm days and cool nights, especially if the lawn is thirsty and lacks fertilizer.
Applying fertilizer and watering the lawn with 1 inch of water will curb the disease. To successfully treat leaf spots with fungicide, you must catch the disease in its early stage.
Pest can damage your lawn or cause birds and pest-eating animals to dig holes in your lawn and tear the grass as they scavenge for insects. While some insects are beneficial, others are a nuisance and should be eliminated. Below are some insects that can cause havoc on a zoysia lawn.
- Clinch bugs: Chinch bugs will likely attack your zoysia lawn during the hot summer months. They will invade the lawn from one side causing damages that resemble drought damage. To control them, use an insecticide that kills chinch bugs
- Hunting billbugs: Hunting billbugs are more elusive and will cause yellow patches that will later brown and cause grass blades to die. The damage resembles drought damage. Use insecticide meant for hunting billbugs to kill them.
- Grubs: In large numbers, grubs can cause havoc on irrigated lawns. They will cause the grass to weaken, causing dead patches. Most damage is witnessed between August and September. Use insecticide to control them or apply nematodes.
Zoysia Grass Maintenance Guide
Zoysia maintenance guide varies for different seasons. Below is a month-after-month guide on how to care for your zoysia grass.
1. March to May (Spring)
- Mowing – Mow the grass shorter than usual and bag the clippings. This will help the topsoil heat quickly by reducing shading. Mowing should happen after the grass turns green during spring.
- Fertilization – Feed the grass four weeks after the grass turns green.
- Watering – Water only if there is no rainfall or if the grass starts to wilt or has curved leaves.
- Disease control – Treat any emerging disease.
- Weed control – At the beginning of March, apply pre-emergent herbicide to control crabgrass. Also, use a post-emergent to control the broadleaf weeds that may emerge.
2. June to August (Summer)
- Mowing – Mow once every week.
- Fertilization – Apply 0.30 kg of nitrogen fertilizer per 100 Square meters between June and July and repeat in mid-August.
- Watering – Water with 1 inch of water per week.
- Disease control – Zoysia is susceptible to rust during summer. Use nitrogen fertilizer or use a fungicide.
- Weed control – Use a post-emergent herbicide to control broadleaf weeds if present.
- Sodding – Sod bare patches and keep them moist for two weeks. Sod will settle in faster in summer than spring.
3. September to November (Fall)
- Mowing – Cut the grass once every week. The clippings can be left on the lawn.
- Fertilization – Not necessary if you had fed the lawn in spring and summer.
- Watering – Water only when necessary.
- Disease control – Treat with appropriate herbicide.
4. December to February (Winter)
- Fertilization – Do not fertilize.
- Watering – Water if you have planted new sod. Water only when necessary for the existing lawns.
- Weed control – Do not use glyphosate to control weeds in winter.
Note: Do not exceed two weed control applications per year and allow 30 days between treatments. Aerate and dethatch the lawn in spring and summer when the grass is actively growing.
Zoysia makes a hardy lawn but also faces some lawn problems like thatch build-up, lawn diseases, and insects. To counter them, you must follow a proper lawn maintenance guide on watering, disease control, fertilization, dethatching and aerating.
- The University of Missouri, Integrates Pest Management, My Zoysiagrass Lawn was Beautiful
- Oklahoma State University, Large patch (Zoysia Patch) of Warm-Season Turfgrasses
- The University of Florida, Zoysiagrass for Florida Lawns
- Clemson Cooperative Extension, BROWN PATCH & LARGE PATCH DISEASES OF LAWNS