Lawn Fungus Control – Lawn Disease Control

Protect your lawn from fungus and diseases

Snow mold is among the most common lawn diseases – usually appearing in early spring after a particularly snowy winter. Snow mold occurs when snow falls on unfrozen grass and remains on the grass for an extended period of time – compacting the blades.

The first symptom of snow mold is straw colored patches in your lawn that are anywhere between 3 to 12 inches in diameter. Although snow mold is likely to go away on its own, there is a chance that patches of your lawn could die and seeding or sodding would be necessary.

One of the most important things you can do to help contain snow mold is to rake your lawn as soon as the snow finally melts. Doing so will break up the matted down patches of grass – allowing the grass to breathe and dry out from the sun, thus discouraging fungal development.

3 Early Spring Lawn Care Tips

Lawn Fungus: Necrotic Ring Spot Control

The most common Colorado lawn disease is Necrotic Ring Spot (NRS), a perennial lawn fungus that causes round or doughnut-shaped patches of dead grass. This soil borne fungus affects Kentucky Bluegrass. Although NRS thrives in our arid climate and weather conditions, it can be controlled by the use of resistant varieties, good turf management practices and fungicide applications.

Necrotic ring spot, lawn care disease

Necrotic Ring Spot (NRS) is a fungal disease affecting stressed lawns and is active from May until October. NRS first appears as small, scattered, straw colored patches. As it progresses, the rings become crater like scars. Often tufts of green grass remain in the center, giving the lawn a frog eye appearance. Swingle’s lawn program, along with your everyday good lawn care practices, can better suppress this disease.

What you need to do to prevent lawn diseases

Mowing: The highest setting on your lawn mower will help shade the soil, keeping the roots cooler in the hotter months. A taller lawn height also conserves moisture and promotes lateral growth to thicken the lawn. A sharp mower blade will also improve the general health and appearance of the lawn. (2 1/2” to 3” mow height)

Watering: Necrotic ring spot almost often occurs in lawns receiving too much moisture, however reducing your watering practices is not the answer. The goal of lawn watering is to effectively wet the soil to a depth of 6 to 8 inches, without water puddling on the soil surface.  During the growing season we recommend one 15 minute watering in the morning, and one 15 minute watering in the evening. During the spring and fall, watering two days per week should suffice. During hot and dry summer months, watering 3 days may be necessary.

Reseeding: Often over-seeding with a blend of disease resistant seed will help re-established your lawn in damaged areas. We recommend a blend containing perennial ryegrass.

Fertilizer:  Abundant soil fertility also encourages NRS development. Withholding some nitrogen fertilizer, while making the lawn just a bit less lush, will discourage necrotic ring spot. The secret to good NRS management is to provide a balanced fertilization regimen, which avoids peaks and valleys in nutrition. That is, apply fertilizer that slowly releases nutrients into the grass plant. Swingle offers two different fertilization programs designed for necrotic ring spot management.

Organic based fertilizer

This fertilizer is primarily derived from organic sources including alfalfa, blood meal, cottonseed meal, urea, and ferrous sulfate. Applied five times during the season, this fertilizer provides readily available nutrient and also includes a slow release component. Biological stimulants are also included to increase microbial activity. Soil microbes break down the thatch layer into useable nutrients for the grass – it also increases the soil biodiversity.

Time released engineered fertilizer

This fertilizer is applied once during the season – either in the spring or fall. Caliber Cote releases nutrients when the soil is moist. The slow release of nutrients helps the turf grow steadily – promoting healthy root growth, while maintaining a green lawn.

Results: We do not guarantee control for Necrotic Ring Spot. We have found, however, that improved lawn care practices can greatly reduce the scarring that occurs. Following our recommendations for both lawn care practices and treatment will help suppress NRS damage. In turn, this will encourage new growth which will fill in old NRS scars and improve your lawn’s health and appearance.

Control of Lawn Fungus: Ascochyta – Kentucky Bluegrass Fungal Disease

Ascochyta is another common lawn disease. A fungal disease that occurs with Kentucky Bluegrass. It’s most prevalent in the spring and summer when lawns are stressed due to variable moisture conditions and temperature fluctuations. It can occur throughout the growing season.

Lawn Diseases and Lawn Fungus

Individual blades start dying back from the tips, withering towards the base of the grass blade causing the leaf tip to appear pinched. In most cases, pockets of infection will cause a patchy or streaked appearance.

The area will recover in 2-3 weeks with additional watering and mowings.


What can be done to help your yard?

  • Core aerate to reduce thatch buildup
  • Keep mower blades sharp
  • Mow grass to a height of 2 1/2 to 3 inches
  • Do not mulch your lawn if you have ascochyta
  • Keep mower wheels and shoes used when cutting the lawn clean, as this can spread the fungus
  • Water in the morning so leaf blades can dry quickly
  • Water the affected area with more water less often
  • Use a soil conditioner such as REVIVE to improve your lawns water efficiency


If you believe your lawn has a disease, contact Swingle today for a no-cost evaluation with a lawn care expert!

As an additional benefit, we also provide evaluations for Japanese Beetle grubs throughout the year. If treatment is necessary, additional charges will apply.