Lawn diseases: Tips for detection and control

Every garden owner wants a beautiful, healthy lawn. However, depending on the season, different lawn diseases can occur, which in most cases are noticeable by unsightly discoloration or bare patches. We explain how you can detect the most common lawn diseases as early as possible and treat them effectively, so that your lawn will quickly be gloriously green again.

Development and treatment of lawn diseases

Most lawn diseases are caused by a lack of or incorrect supply of nutrients. Poor aeration of the soil and roots, unbalanced watering, improper lawn cutting, or even the weather can also trigger lawn diseases.

Often it is fungal infestation in a wide variety of forms. But pests can also affect the lawn. To anticipate one thing: Prophylaxis as well as treatment is similar for almost all fungal lawn diseases.

  • Ensure sufficient aeration of the soil, e.g. by (semi-)annual scarifying or aerification. Sand the subsoil if necessary.
  • Remove leaves and coarse manure residues so that the grass blades receive sufficient light and oxygen.
  • Mow regularly, shortening the lawn to no more than 1/3 of the blade length.
  • Mulch to return nutrients to the grass through the fine grass clippings.
  • Ensure optimal watering of lawns, or by using an irrigation computer and sprinklers connected to it.
  • For new lawns and reseeding, use only high-quality lawn varieties that are suitable for the area. For example, use shade turf in areas with little sunlight.
  • If necessary, provide the soil with additional nutrients through balanced fertilization.

Red tip

If the lawn is infested with a pink to reddish, needle-like fungal growth, it is redpointedness
If the lawn is infested with a pink to reddish, needle-like fungal growth, it is redpointedness

One of the best-known lawn diseases is red shag. If the lawn is heavily infested, it can even die completely in the worst case. In a normal course of the disease, however, the affected section of the lawn recovers quickly.

Symptoms of red shrew

You can recognize red tip disease by the pink to reddish, needle-like fungal tangle that spreads across the top of the blades. In advanced stages, the culms can become stuck together due to the fungal tangle. The disease begins by small, brownish spots in the turf. It occurs mainly when the has a nitrogen deficiency, incorrectly watered or but not fertilized. Too high (air) humidity can also be the cause of red top.

Control of red shrew

To prevent the fungal infestation from occurring in the first place, we recommend a lawn fertilizer containing nitrogen as well as potassium to compensate for any nutrient deficiency. With the help of a scarifier or aerator, you can additionally loosen the soil and ensure better aeration.

In addition, leaves or manure residues should be removed, e.g. by means of a leaf vacuum, as these deprive the lawn of additional oxygen and light. Longer blades of grass are also less susceptible to red tip, so you should not cut your lawns too short.

Disease typeFungal infestation
Seasonyear-round infestation
mainly March to October
at temperatures between 5 and 30 °C
Symptomsyellowish to brownish grass blades
pink to reddish fungal tangles
Controlremove grass cuttings and leaves
scarify / aerate
use lawn fertilizer containing nitrogen and potassium

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Snow mold

Snow mold is usually identifiable in the spring by the brown spots and circles
Snow mold is usually identifiable in the spring by the brown spots and circles

Snow mold is also a fungal disease. It occurs mainly in the cooler season (spring or fall) and can develop well at an outdoor temperature of 10 °C.

Symptoms of snow mold

If the lawn is affected by this fungal disease, then small, dark brown or orange spots appear in the lawn. Over time, these become larger and spread. In addition, you can also recognize snow mold by the wet grass, which is covered with a film of slime.

Control of snow mold

The quick mold can survive only at temperatures up to 20 degrees Celsius. At higher outdoor temperatures it dies. It is recommended to scarify the lawn afterwards and reseed the bare spots. This fungal disease can also be prevented with sufficient light and air as well as good seed quality.

You can find out more about this lawn disease in the guide Snow mold: Winter tips for your lawn.

Disease typeFungal infestation
Seasonmainly September to March
mostly visible in spring
Symptomsdark brown or orange round spots
first 3 to 4 cm in size, later up to 30 cm
Controlfrom 20 °C the lawn heals by itself
scarify and sow new lawn
ensure sufficient aeration
fertilize if necessary

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Witch rings / fairy rings

Mushroom circles on the lawn indicate witch rings
Mushroom circles on the lawn indicate witch rings

The so-called witch rings or fairy rings are also triggered by a fungal disease. There are three different forms, but they differ only in terms of the process by which they develop. The prophylactic measures and the control methods are identical.

Symptoms of witch rings

All three types can be recognized by a round discoloration on the lawn surface. Overnight, the fungi also shoot out of the ground in a circular pattern. Unfortunately, if the fungal infestation occurs, it is no longer easy to remove. The reason for the appearance of the disease is due to a nutrient-poor soil, so you must first perform a soil analysis. This will allow you to determine what the nature of the soil is and what nutrients are stored. In this way, you can find out how often fertilization of the lawn is necessary.

Control of witch rings

To prevent the lawn disease witch rings, it is best to aerate the lawn with the help of a scarifier. Unless you dethatch the area regularly, nutrients can no longer be absorbed and the development of witch rings will be greatly enhanced.

If the fungal disease has already appeared, it is recommended to soak the mushrooms with water and cover them with sand. Sometimes it also helps to divide the mycelium with the help of a digging fork. In the worst case, you need to remove the soil to a depth of 30 cm and replace the soil.

Disease typeFungal infestation
Seasonyear-round infestation
SymptomsWitch’s ring type 1: dark green rings on which small fungi grow, grasses in the ring area die off
Witch’s ring type 2: dark green rings with increased fungal growth, grasses survive
Witch’s ring type 3: increased ring-shaped fungal growth without lawn damage
ControlAerate lawn with scarifier and sand afterwards
water fungal circles intensively
divide water-impermeable mycelium
fertilize in a balanced way
in the last instance replace the soil

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Root blight / Pythium rot

When root burn the stalks droop and sunken spots appear
When root burn the stalks droop and sunken spots appear

Root blight, also called Pythium rot, mainly affects new lawn seed; well-developed lawns are rarely affected by this lawn disease. Causes of root blight include drought, excessive fertilizing, or lawn thatch. However, it can also be caused by lawn seeds that were already infected before seeding.

Symptoms of root burn

You can recognize the disease has the limply hanging down blades and brown discolored root neck. In addition, sunken patches on the lawn are also often evident.

Root blight control

To be able to prevent this effectively, high-quality seed and balanced fertilization are essential for new planting or reseeding. In addition, the soil should be permeable and optimally watered.

Disease typeFungal infestation
Seasonmainly May to September
at high humidity and temperature
Symptomsaffected areas are light and slightly sunken
dark root neck
white mycelium is visible in humid conditions
Controluse only high quality seeds
fertilize in a balanced way
scarify and sand if necessary
ensure optimal watering

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Leaf spot disease

Leaf spot disease is recognized by the whitish-yellow to brown spots on the culms
Leaf spot disease is recognized by the whitish-yellow to brown spots on the culms

Leaf spot disease is another fungal disease that often affects grasses that suffer from poor conditions, are heavily compacted, or are somewhat older. It is caused by persistent moisture, poor fertilization or lawns that have been mowed too low. Fortunately, this lawn disease does not cause much damage.

Symptoms of leaf spot disease

Leaf spot disease can be identified by the whitish-yellow to brown or even olive-green spots on the leaves. The size is variable.

Control of leaf spot disease

Ensure adequate aeration of the soil by mowing and scarifying regularly, not too deeply. In addition, a controlled application of fertilizer can also help. Drought as well as overwatering should be avoided to prevent leaf spot disease. Watering computers help to optimize the water supply to lawns.

Disease typeFungal infestation
SeasonMarch to May or August to October
at temperatures between 10 and 30 °C
Symptomswhitish-yellow, brown or olive-green spots on culms
ControlShorten grass with a lawn mower regularly to a maximum of 1/3
scarify the soil and ensure sufficient aeration
fertilize in a controlled manner
Avoid drought and too much water

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Last update was on: May 25, 2024 8:07 am

Powdery mildew

Powdery mildew produces a white, cotton wool-like coating on the leaves
Powdery mildew produces a white, cotton wool-like coating on the leaves

This lawn disease usually occurs on lawns that are in the shade and mowed too deeply. Powdery mildew is also favored by warm, humid weather and the resulting waterlogging.

Symptoms of mildew

Powdery mildew can be recognized by white spots on the upper side of the leaves, which are cotton-wool-like at first and later develop into a white coating.

Control of powdery mildew

Powdery mildew is best controlled when light conditions on the lawn improve. To do this, for example, trees and bushes can be removed or at least thinned out. When planting a new lawn, special shade turf should be used that can get by with little light and sun. The lawn mower should be set to a higher cutting height and the area scarified once or twice a year.

Disease typeFungal infestation
Seasonyear-round infestation
at temperatures between 0 and 30 °C
Symptomswhite, cotton wool-like spots on the upper side of the culms
in the further course white coating
Controlthe light conditions should be improved
use special shade lawn
do not mow the lawn too short (max. 1/3)
scarify or aerify the lawn


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