Common Lawn Diseases

Lawn diseases and fungal infections can be hard to spot, and even harder to identify. These issues can worsen with heat and drought during the summer or heavy rains in the spring and fall. They can negatively impact your lawn's appearance, growth, and overall health. In this post, we'll review some common lawn diseases to help you identify them and take the right steps to improve your lawn’s health. 

We will review common diseases on this page to help identify them and improve your lawn. 

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Rust 

One of the most common diseases we see is rust, a fungal infection that can often be mistaken for other lawn issues. While primarily cosmetic, it’s caused by several types of fungi. Symptoms include orange dust on your shoes, grass turning yellow or orange, and small yellow spots on the grass blades. Rust thrives in warm, moist environments where grass is stressed or growing slowly due to poor maintenance. Common causes include mowing too short, low nitrogen levels, inadequate watering, overwatering, or soil compaction. To treat rust, a good fertilizer application, proper aeration, and improved lawn care practices are usually enough to get it under control. 

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Red Thread 

Red thread is another fungal disease that can plague lawns, often caused by improper watering and a thick thatch layer. This fungus thrives during periods of high humidity when the soil or lawn surface is wet, but the roots stay dry due to water not penetrating the thick thatch layer. Red Thread can be easily mistaken for Dollar Spot or Fairy Ring but it is differentiated by the pinkish-red, antler-like threads at the tips of infected grass blades. To combat red thread, apply fertilizer, aerate, dethatch, and adjust your watering practices. 

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Dollar Spot 

Dollar Spot is another common fungal lawn disease that causes fuzzy, wet, white, or tan spots covering the tips of grass blades. Spots can start small but gradually get bigger and merge to create dead grass patches. This occurs due to too frequent or improper watering and poor drainage creating wet conditions which allow the fungus to thrive. More severe cases happen in lawns with low nitrogen levels, low mowing heights, and compacted soil. To fix, adjust your watering schedule, aerate, raise your mowing height, apply a balanced fertilizer, and reseed areas that have died off. 

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Fairy Ring 

Fairy ring, similar to Dollar Spot, is another commonly seen fungal disease that creates circle-shaped patterns and includes three different types. 

Type 1: Appears with a ring of wilted, brown, dead grass and is the most damaging to turf. The soil and thatch are extremely dry in these cases and make an almost waterproof layer above the roots. 

Type 2: Produces a dark green ring and grows faster than the surrounding turf due to the release of nitrogen from the fungal breakdown of organic matter in the lawn.

Type 3: Produces a ring of mushrooms or puffballs that commonly appears with frequent and/or heavy rainfall. With regular waterings in the morning, a higher mowing length, and fertilizer, the ring should go away within a month. 

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Gray Leaf Spot 

This fungal infection causes the grass in the lawn to look wilted and irregular, with brown and gray spots appearing on the grass blades from June to August. Several reasons for this can include a too-thick thatch layer, low mowing height, extended periods of leaf wetness, nitrogen deficiency, or poor irrigation. It is recommended that watering be done in the morning, the mowing height be raised, and the thatch layer be removed in early spring or early fall. Apply liquid aeration and a balanced fertilizer to improve lawn health. 

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Necrotic Ring Spot 

Necrotic Ring Spot is a fungal disease for turf grasses and lawns that is fairly common. The signs of it are lighter green patches that eventually turn into rings of bronze grass with healthy grass in the middle. This bronze grass eventually weakens and turns straw/tan colored. This occurs due to overwatering the lawn and having compacted soil. Aerating the lawn as soon as possible is one of the best recommended solutions, along with reducing watering for the lawn, and using the correct type of fertilizer. 

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Brown Patch 

Brown patch is usually identified by brown, water-soaked spots that are irregular and patchy in shape. This is a root disease that occurs from overwatering and improper aeration. General signs for this include circles or streaks and wilted, irregular spots that are brown, orange, and over-soaked with water. Be sure not to water at night or for longer than is needed. To repair, adjust your watering schedule, apply liquid aeration and a balanced fertilizer. 

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Iron Chlorosis 

Iron chlorosis is a condition caused by an iron deficiency that affects grass growth. The most common cause is alkaline soil, where the pH level exceeds 7.5, often due to an accumulation of sodium, calcium, and magnesium. This high pH decreases the availability and absorption of essential nutrients like zinc, iron, copper, manganese, and phosphorus. In addition to soil pH, cooler, wet conditions—such as heavy rainfall or overwatering—can contribute to iron chlorosis. Some grass species, such as St. Augustine grass, are particularly sensitive to low iron levels. Symptoms of iron chlorosis include yellowing of the shoot tips and young leaves, along with dark, vertical veins in the grass blades. Treatment typically involves both environmental adjustments and chemical treatments. Reducing watering frequency but increasing the duration of each session can promote deeper root growth. Aerating the soil helps improve nutrient, air, and water penetration to the roots, supporting better iron absorption. Iron supplements can also be applied to help lower the soil’s pH and make iron more accessible, aiding in the grass’s recovery.

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Summer Patch 

Summer patch is a turfgrass root disease that can be tricky to identify early on. Symptoms typically start to appear during the mid-summer months, when infected roots struggle to support the grass blades under heat and drought stress. It’s often confused with brown patch, as both diseases cause similar discoloration, but summer patch infections are irregularly shaped, whereas brown patch is circular. To treat summer patch, focus on aerating the soil, maintaining consistent watering during dry periods, and fertilizing. These practices will help the grass recover, eventually outgrowing the fungal infection. We recommend avoiding fungicides, as they tend to be expensive and generally ineffective. 

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With this information, you’re now better equipped to address any challenges that may hinder your lawn from thriving. Hopefully, it provides you with useful insights on how to manage issues or infections that can arise during the growing season. With this knowledge and All Green’s help, you can cultivate the healthy, full lawn you are looking for.