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What Is Rust Disease?


Rust is a fungal disease that affects many types of turfgrasses. It is appropriately named for the orange or brown rust-coloured spots it produces on the grass blades. The disease can cause the leaves of grass plants to turn yellow, wilt, and die, leading to thin and patchy lawns. Rust favors warm and wet conditions, occurring most prominently in late summer and fall, when there are conditions of low light intensity and temperatures between 22ºC and 27ºC.


The disease is caused by a group of fungi commonly found in soil and plants. It survives on living and dead leaf tissue in the thatch layer of the lawn. When conditions become suitable, the disease will occur quite rapidly. A variety of factors can contribute to the growth of Rust, including improper watering, high humidity levels, and fluctuating weather patterns. Reddish orange spores develop in large numbers on the leaves of the grass plants and are easily rubbed off on shoes, clothing, animals, mowing equipment, or other objects that pass through the infected areas. However, as conditions improve and cultural practices are altered, the grass is normally able to recover.


How Can I Control Rust Disease In My Lawn?


Rust is considered a minor disease. It usually does not cause permanent damage to the turf, unless its favourable conditions continue for an extended period of time. In most cases, a change in the weather can help reduce the spread of this disease. You can also adjust your cultural practices to improve the health of the lawn and further limit the spread of the disease. However, depending on the size of the infestation and the scope of the damage, other forms of control may be necessary. 


A thick, healthy, well-maintained lawn is the best line of defense. Here’s how you can adjust your beneficial cultural practices to reduce the spread of Rust disease:

  • Avoid Watering: Under normal circumstances, you should be watering each area of your lawn for 30-45 minutes, twice per week, in the early morning so the turf is dry by nightfall. However, you should avoid watering when the disease is active.

  • Avoid Mowing: You should avoid mowing when the disease is active. If you do have to mow, make sure your mower blade is razor sharp, so that the blade does not fray the tips of the grass, spreading the disease. Maintain a regular mowing schedule throughout the growing season. In general, you should keep your lawn between 2 ½ and 3 ½ inches high, but during the hottest weeks of summer, you may allow the grass to grow as high as 4 inches. Never remove more than ⅓ of the grass blade at each mowing. 

  • Fertilize Regularly: Regular applications of Weed Man’s specially formulated, slow-release granular fertilizer will help provide your lawn with adequate nutrients. These applications are timed specifically to avoid over fertilizing the lawn.

  • Core Aeration: Aerating your lawn can improve soil drainage and help reduce the likelihood of lawn diseases. This will also alleviate soil compaction and allow water and nutrients to penetrate deeper into the soil.


Your local Weed Man professional may be able to offer other solutions and recommend the best form of treatment that is available to improve the conditions of your lawn.