Understanding Lawn Care Brown Patch Disease Causes and Symptoms

Brown patch disease is a common issue that can wreak havoc on your lawn. It's a fungal disease that thrives in warm and humid weather.

The primary cause of brown patch disease is a fungus called Rhizoctonia solani. This fungus is highly adaptable and can infect a wide range of grass species.

Brown patch disease is most active during the hot summer months when temperatures are consistently above 65°F. This is because the fungus thrives in warm and humid conditions.

Symptoms of brown patch disease include circular patches of dead grass that can range in size from a few inches to several feet in diameter.

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Brown patch disease is a fungal infection that can quickly ruin the beauty of your lawn. It's caused by a strain of Rhizoctoniasolani, a fungal pathogen.

The disease is most common on cool-season grasses like tall fescue, ryegrass, bluegrass, and bentgrass. These grasses are typically affected during late spring and summer.

Leaf wetness and suitable temperatures trigger the disease's rapid development. This can happen when there's an extended period of wet leaves.

Symptoms of brown patch can appear on these grasses during warmer winter months as well.

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Brown patch fungus can be tricky to spot at first, but knowing what to look for is key to protecting your yard. One of the first signs of trouble is a circular or oblong pattern of light-yellow discoloration in your grass.

In fact, the fungus doesn't start out brown at all - it begins with a light-yellow discoloration that eventually turns orange to tan. This discoloration is caused by the fungus infecting each leaf, causing them to rot.

You might notice circular patches in your lawn, ranging from a few inches to several feet across, with irregular tan spots and a dark brown or purplish border on the grass blades. At the base of the blade, you might see signs of rot.

A white, cobweb-like fungus (mycelium) might appear around the grass blades in the early morning, before the dew dries. This is a sign that the fungus is present.

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Here are the tell-tale signs of brown patch fungus:

Tall fescue, perennial ryegrass, and bentgrass are commonly affected by brown patch fungus, particularly in cool-season climates.

Tall fescue lawns less than a year old can be killed by brown patch, but mature lawns can recover in most cases.

Some warm-season grasses, like St. Augustinegrass and zoysiagrass, are also susceptible to brown patch.

Tall fescue is the most common and important disease of in the Southeast, with Kentucky-31 tall fescue showing more resistance to brown patch than other cultivars.

Perennial ryegrass does best in cooler weather, but hot, damp conditions can make it vulnerable to fungal problems like brown patch.

Here are some grasses that are prone to brown patch lawn disease:

Symptoms of brown patch disease can vary greatly depending on the type of grass and soil conditions. Infected warm-season grasses rarely have leaf spots, but instead have rotted leaf sheaths near the soil surface.

The center of the diseased area may recover as the fungal activity moves outward, resulting in a doughnut-shaped pattern. Large patch disease often becomes evident in the spring, as St. Augustinegrass and other warm-season turfgrasses green-up.

Damaged areas may coalesce or merge, and in some cases, large areas of the lawn may be thinned and killed without the formation of noticeable circular patches.

Symptoms can vary greatly depending on the type of grass and soil conditions, but they often start with thinned patches of light brown grass that are roughly circular in shape.

These patches can range in diameter from a few inches to several feet and may coalesce or merge, creating larger areas of damaged turfgrass.

On St. Augustinegrass, you might see a doughnut-shaped pattern as the turfgrass in the center of the patch recovers, but during favorable conditions, large areas of the lawn can be thinned and killed without noticeable circular patches.

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Large patch disease on centipedegrass often results in a rounded pattern of dying turfgrass as the disease-causing fungus moves outward in all directions.

You might notice that infected warm-season grasses rarely have leaf spots, but instead have rotted leaf sheaths near the soil surface.

If you gently tug on the leaves in the recently discolored perimeter, the blades will often pull free, which is a diagnostic sign of the disease.

Close inspection of cool-season grass blades reveals small, irregular, tan leaf spots with dark-brown borders.

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Brown patch is a midsummer disease, often occurring when night temperatures are above 68°F and daytime temperatures average 80°F or above. Rainy weather and a saturated atmosphere greatly speed disease development.

High levels of nitrogen fertilizer can make the disease worse, especially on lush, succulent turf. Moderate nitrogen levels and dry conditions can help prevent the disease.

Perennial ryegrass, creeping and colonial bentgrasses, and tall fescue are particularly susceptible to brown patch disease. Kentucky bluegrass and the fine fescues are less likely to develop symptoms.

Turf stands less than one year old are more likely to sustain severe brown patch damage.

To prevent brown patch disease, it's essential to create a healthy lawn environment. A healthy lawn is the best defense against any disease, including brown patch. Water your lawn in the morning to allow the grass blades to dry, and avoid watering between 7 PM and 3 AM.

Regular fertilization is also crucial. Feed your lawn four times a year to keep it healthy, but be careful not to overapply nitrogen fertilizer before a hot, humid spell, as this can encourage brown patch. Water deeply but not too oftenUse a balanced fertilizer and follow recommended rates

If you do get brown patch, it's not the end of the world. You can treat it with fungicides, but it's essential to act quickly. Some multisite contact fungicides labeled for control of brown patch disease include chlorothalonil, fluazinam, and PCNB (quintozene).

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Brown patch is a fungal disease that thrives in heat and humidity, typically appearing in late spring, summer, or early fall. Daytime temperatures above 80°F and nighttime temperatures above 65°F create ideal conditions for it.

This excess moisture can come from summer rain, evening watering, or poor drainage. Lawns that have been overfertilized with nitrogen right before or during hot, humid weather are also more likely to develop brown patch.

Excessive moisture is exactly what Rhizoctonia solani needs to grow. This fungus can stay dormant in soil or thatch until conditions encourage it to grow.

Here are some common causes of brown patch:

A thatch layer over half an inch thick can trap moisture at the soil’s surface, creating a hot spot for brown patch fungus. This can happen even if you're not overwatering your lawn.

Brown patch fungus thrives in heat and humidity, and typically appears in late spring, summer, or early fall. The ideal conditions for it are daytime temperatures above 80°F and nighttime temperatures above 65°F, combined with prolonged wetness.

Excessive moisture is a key factor in brown patch fungus growth. Overwatering or poor drainage keeps grass blades damp, creating a perfect environment for the fungus to grow.

High humidity and warm nights also contribute to brown patch fungus growth. When days are hot and nights stay warm and humid, lawns may never fully dry out, which helps the fungus grow.

A thick thatch layer can trap moisture at the soil's surface, making it a hot spot for brown patch fungus. A thatch layer over half an inch thick can lead to soggy conditions, ideal for the fungus.

Excess nitrogen can also lead to brown patch fungus. Heavy nitrogen fertilization can make grass blades tender and more susceptible to infection.

Brown patch fungus typically attacks cool-season grasses like tall fescue, perennial ryegrass, and bentgrass. Some warm-season grasses, such as St. Augustinegrass and zoysiagrass, are also susceptible.

Here are some common grass types that are prone to brown patch fungus:

Prevention is key when it comes to brown patch disease. A healthy lawn is the best defense against any disease, including brown patch.

Watering your lawn in the morning allows the grass blades to dry out before nightfall, reducing the risk of disease. Avoid watering between 7 PM and 3 AM.

Feeding your lawn regularly with a balanced fertilizer can help keep it healthy and strong. A well-fed lawn is less susceptible to disease, but be careful not to overapply nitrogen fertilizer before a hot, humid spell.

Good air circulation and drainage are essential for preventing brown patch disease. Prune overgrown trees to let more sunlight and air in, and aerate and dethatch your lawn every 1 to 3 years to reduce compaction.

Water management is crucial in preventing brown patch disease. Irrigation should only be used to supplement rainfall, and rain sensors and smart controllers can help prevent overwatering.

To prevent brown patch disease, water deeply but not too often, and fertilize wisely with balanced nutrients. Aerating your lawn regularly can also help prevent disease by breaking down thatch and loosening soil.

Monitoring your lawn mowing height is also important, as grass that's cut too short is more susceptible to fungal infections. Keep your lawn at the recommended height for its type, and use a sharp mower blade to avoid stressing the lawn.

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Here's a list of some multisite contact fungicides labeled for control of brown patch disease:

Some penetrant fungicides labeled for control of brown patch disease include:

If you do notice brown patch disease on your lawn, act quickly and adjust your watering habits, improve airflow and drainage, and mow correctly to prevent further damage.

Controlling brown patch disease requires a multi-step approach. First, you need to prevent the spread of the fungus to healthy parts of your lawn.

Affected areas should not be mowed, as that could cause diseased clippings to deposit elsewhere, spreading the infection. This can be a challenge, especially if the affected area is in a high-traffic zone.

Fungicide treatment is sometimes necessary, especially on high-value perennial ryegrass or bentgrass turf stands. In areas where brown patch causes severe thinning, preventative fungicide applications may be justified.

Some fungicides can be used on a curative basis, with the first application being made immediately after the onset of symptoms. This is especially important if prolonged hot, humid weather is expected.

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Here are some multisite contact fungicides labeled for control of brown patch disease:

It's essential to note that self-diagnosis and treatment could make the problem worse. If you suspect brown patch disease, it's best to have your lawn assessed by an experienced landscape professional.