As is the case with managing most lawn diseases, maintaining best management practices, such as proper mowing, watering, core aeration and fertility, will go a long way in reducing the occurrence of dollar spot lawn disease.
Leaf tip dieback with red, thread-like filaments appearing.
Irregular beige patches from a few inches to a few feet in diameter.
Best way to treat or prevent:
Collect clippings when the disease is present.
Apply a high-nitrogen-source fertilizer at the recommended rate.
Disease should disappear in a couple of weeks with adequate fertilizer. If not, you can use a broad-spectrum fungicide like Scotts DiseaseX Lawn Fungicide.
Good to know:
Red thread lawn disease often appears in spring and fall during humid, cool conditions.
Reseeding with disease-tolerant lawn seed varieties will help.
Most prevalent in northern U.S. in cool-season lawn grasses.
What causes it?:
Prolonged hot, humid conditions.
Compacted soils that don’t drain well.
Brief physical description:
Can begin as small circular patches that grow into larger patches up to 18 inches in diameter. These patches can coalesce into larger areas.
Affected areas can appear wilted, progressing into reddish-brown or light-brown sunken patches, often with a tuft of healthy grass in the patch’s center.
Best way to treat or prevent:
Promote good root growth by core aerating and improving drainage.
Raise mowing height to about three inches.
Overseed with perennial ryegrass or seed new lawns with tall fescue. Both are genetically resistant.
Cool, wet weather conditions, followed by heat and drought stress.
Over-management of your lawn (too much fertilizer and water).
The presence of a thick thatch layer.
Brief physical description:
Light-green to straw-colored patches usually less than 12 inches in diameter.
Regrowth may occur in the center of the patch, creating a “frog eye” appearance.
Best way to treat or prevent:
Reduce nitrogen fertilizer.
Core aerate regularly to reduce soil compaction and thatch layer.
Plant disease-tolerance seed varieties.
Fungicide treatments can be iffy, but using a professional-grade fungicide, like Syngenta Headway G or Quali-Pro Propiconazole 14.3 will give you a fighting chance. Make sure you follow label instructions.
Good to know:
Buying sod consisting of newer varieties resistant to this disease will help.
Sowing your lawn from seed will reduce your odds of getting necrotic ring spot.
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Tomasz Klejdysz/Getty Images
Leaf Rust
Also known as:
Puccinia spp.
Where is it found?:
Throughout the U.S. in all types of lawn grasses.
Most commonly, on perennial ryegrass.
What causes it?:
The most common cause is the lack of nitrogen fertilizer.
Low soil moisture and high humidity.
It is most problematic in late summer or early fall.
Brief physical description:
Yellow flecks appearing on leaf blades are the first sign.
Lawns can take on a yellow or orange tint.
These yellow flecks advance into pustules that can burst causing orange powdery spores to release.
These rust-colored spores can cover shoes, mowers and even pets. They are not harmful to humans or animals.
Leaf rust is a nuisance lawn disease that causes no harm to your turf.
A single application of nitrogen fertilizer will provide quick results.
No fungicide applications are recommended or needed.
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Tomasz Klejdysz/Getty Images
Powdery Mildew
Also known as:
Erysiphe graminis
Where is it found?:
In heavy shade.
In slow growing lawns.
What causes it?:
Low light intensity.
Cooler temperatures, between 60 and 70 degrees and high humidity.
Poor air circulation.
Brief physical description:
Cobwebby-type growth on the upper surface of leaf blades.
In advanced cases, leaf blades appear completely coated with talc or flour.
Best way to treat or prevent:
Increase light penetration and air circulation by pruning or removing trees and other vegetation.
Reduce watering if areas remain unusually wet for long periods.
Lightly fertilize to promote foliar growth. That way you’ll remove the infected leaf blades quicker.
Good to know:
Powdery mildew is not harmful to your lawn. There is no need to chemically treat.
It can also show up in gardens, perennials and other ornamental plants.
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