Common Zoysia Diseases And Treatments

Zoysia is warm-season grass native to Asia. It captured American interest in the 18th century and since then become popular amongst United States homeowners. Zoysia requires little or no maintenance and is preferred to traditional lawn grass. It’s a thick and hardy grass that chokes out weeds and requires less fertilizing, mowing, and watering.

Common Zoysia Diseases And Treatments

Zoysia Grass At A Glance

  • Dense and tolerant of traffic
  • Heat and drought tolerant
  • Suitable for southern transition zones
  • It’s a warm-season grass
  • Prefers sun

Zoysia Diseases and Recommended Treatment

Like other grasses, Zoysia is not without faults, though it’s a bit resistant to common grass pests and diseases. If properly cared for, Zoysia lawns can withstand several conditions. Here are common Zoysia diseases.

1. Brown Patch

Brown Patch on zoysia
Brown Patch

Of all Zoysia diseases, the brown patch is the most prevalent. Brown patch is a result of high night temperatures of over 68 degrees and 80 degrees day temperature. It’s a result of excessive fertilization. Patches start small and start distancing as the disease spreads to form dead patches more than 3-feet apart. A common indication of a brown patch is a ring of brown grass surrounding a patch of green grass. 

Brown patches can be avoided by moderate fertilization in summer. Watering in the early morning hours is preferred since temperatures are relatively low. If the disease is spread already, there are fungicides available for treatment. Follow the application procedure carefully to understand the rate and timing of the application. 

2. Dollar Spot

Dollar Spot on goysia
Dollar Spot

A dollar spot can be seen at any point during the plant’s growing time. It is most prevalent on warm days and cool nights. Dollar spots are the size of your hand and are very noticeable on closely mowed lawns. The affected areas are particularly on the edge of the grass blade and may spread across the blade; in effect, the tip dies. A good distinction between a dollar spot from a brown patch is the lesion development in color and pattern. 

Dollar spot is a common indication that Zoysia grass lacks nitrogen. The disease is spread easily through water, wind mowers, or anything that can move parts of the grass-fungi from one place to another. Lack of fertilizer and tough drought conditions might trigger the disease.

The main treatment method for dollar spot is the use of organic fungicides. Two commonly used fungicides for dollar spot treatment are Bonide liquid copper and Physan 20. Bonide Liquid Copper is a naturally formulated general treatment plan for Zoysia grass, vegetables, fruits, and flowers. Apply 1.5 to 6 oz with 2.5 gallons of water to 1,000 sq. ft. A proper application will produce results after two weeks. If spotting resumes, repeat the process with a 7-to-10-day interval. Physan 20 is also effective on Zoysia grass. Add one table salt per gallon and spray over the affected areas.

3. Rust

Rust on goysia

Zoysia grass is one of the common hosts for rust disease. It strikes in times of mild to moderate temperatures, especially in the fall season. Rust is commonly noticed through a yellow powder during mowing. It is more severe in shady areas. Rust will first appear as yellowish leaf specks with fungal spores. The affected lawn appears weak and thin and starts forming irregular patches with a rusty tinge. 

Rust occurs due to high humidity, poor air circulation, and more shade. Drought stress and less fertilization as well may be other contributing factors. The spread of the disease is more prevalent with extended wetness in the region. 

Adequate nitrogen in the soil eliminates rust disease. Avoid getting Zoysia grass overly wet. Remember, it does well in dry seasons. Rust spreads faster due to poor aeration. Improve grass air circulation through frequent mowing on recommended grass height and getting rid of grass clippings. 

4. Leaf Spot

Leaf spot is also a common disease affecting Zoysia grass. The disease is prevalent on warm days and cool nights. The main cause is overly dry conditions and lack of proper fertilization. Leaf spot is caused by a fungus that is more susceptible in shady areas. If an area never dries out, it will be quite hard to control this disease. 

Most homeowners use fungicides in leaf spots treatment which is manufactured in granular form. You must put the right contents of fungicides as indicated in the container to avoid drying out Zoysia even further. The granular can be put together with the fertilizer spreader and water while applying. 

Leaf spot treatment goes for at most two weeks and can be retreated to eliminate the fungi. The disease requires continuous treatment, especially in the summer season. 

5. Fusarium Blight

Fusarium Blight on Goysia
Fusarium Blight

Another disease that is common on Zoysia grass is the fusarium patch. The disease is popularly known by two names; Microdochium nivale if it appears without snow and pink snow mold if it appears after the snowfall. You can easily recognize fusarium blight due to clusters of pink spores on the grace. Clumps of turf tend to clump together as they turn tan. Fusarium occurs in cool temperatures and high humidity. Fusarium blight is more common on golf courses than will be found on home lawns. The high presence of nitrogen may cause a fast outbreak of fusarium blight. 

Once your lawn is diagnosed with this complex fungal organism, various cultural and chemical treatment options are available. However, no treatment option has 100% effectiveness. It is the most complex and stubborn fungi. Many homeowners claim that it’s incurable with different treatment options. The good news is that you don’t have to replace your lawn. 

Fusarium blight has a 3–5-year life span. If it’s not reacting positively to the treatment options given, ensure proper lawn maintenance. Apply fungicides strictly meant for fusarium blight. Make sure to read the instructions in the label before application. Ensure proper soil fertility levels are maintained and keep mowing at bay to prevent further outbreaks.

6. Powdery Mildew

Powdery Mildew
Powdery Mildew

Powdery Mildew is caused by Erysiphe graminis fungus. The fungus is present as small powdery white patches appearing on the upper surface of Zoysia grass. If untreated, the infection spreads to the entire grass fast. 

Powdery mildew is prevalent in high humidity areas and spreads faster is Zoysia grass has poor aeration. It is easily spread across your lawn by spores through the wind. If it’s the first time you are experiencing powdery mildew, look out for old vegetation with spores in the neighborhood and get rid of them. This fungus does well in dry seasons though it thrives better with high humidity levels. It spreads minimally in temperatures above 32-degree C.

Homeowners can treat affected zoysia grass by spraying with preventative fungicides. The best fungicides used for treatment are; sulfur, lime-sulfur, potassium bicarbonate, of neem oil. These chemicals are more effective on the disease when applied as soon as you spot the symptoms. A bicarbonate solution is another clean way to eliminate the Powderly mildew disease. Mix a teaspoon of baking soda in quartz of water and spray the grass thoroughly. The solution eliminates any fungi in contact. 

7. Pythium


Also called cottony blight, pythium is a Zoysia disease whose main cause is poor soil drainage. The disease forms patches that can grow as wide as 12 inches and dies slowly. The dry grass later forms a white mold. 

There are several known species of Pythium causing Pythium blight, the most common being Pythium aphanidermatum. Zoysia is highly vulnerable to this disease due to its high adaptability effect to dry climates. If leaves are wet for more than 12 hours, Pythium blight will spread faster than usual. 

Pythium is a water mold. To avoid its effects:

  • Avoid overwatering the lawn.
  • Provide good water drainage during the rainy seasons to avoid any cases of
  • For best practices, water your grass in minimal amounts and early in the day.
  • Avoid watering during the night or late evening as Zoysia will be subjected to more moisture, thus increasing the spread.

Mowing helps reduce the spread. Mowing should be done when the stem and leaves are dry. Ensure increased mowing height and frequency to promote effective root growth. Here you find the full guide on how to cut zoysia grass.

8. Nematode


Nematodes are parasites that feed on cellular sap. Once Zoysia is affected, it turns yellow, thins out, and fails to grow. Unless you provide urgent lawn care and treatment, the grass is likely to die. Nematodes don’t respond to the watering of fertilization. The roots become swollen and may eventually turn black. Before turning to chemical solutions, make sure you have the right diagnosis. Contact a professional nematode diagnostic lab for a nematode assay to get accurate results. 

Zoysia grass can be nematode infested but no visible symptoms or damages. However, Nematode presence can be witnessed after factors trigger the spread of nematode parasite or if the grass’s susceptibility to nematode increases. 

Nematode parasite is avoided and fixed by avoiding additional stresses on your lawn. Ensure your grass is properly irrigated and fertilized, and ensure your soil has the right nutrients at all times. A properly cared-for lawn can withstand nematode infestation. Compost, municipal sludge, and manure are organic amendments that can improve Zoysia grass health and increase its ability to combat nematode parasites.

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