Tall fescue and bluegrass can be affected by brown patch - a fungus that can create circular brown patches throughout your lawn. The blades of your grass first turn purplish-green, wilt, and then turn light brown. Rot can set in and your lawn will show irregular brown spots from an inch to several feet in diameter. It often appears when there are warm, humid conditions.
Red thread is a common turf disease most frequently occurring in cool wet weather during the spring and fall. Red thread produces a reddish fungal growth seen on leaf blades and after the leaves dry is when it appears to look like small pieces of red string laying in your turf. Usually, the turf has circular patches from 2 inches to 3 feet in diameter.
A common disease in Delaware and Pennsylvania is dollar spot. Dollar spot can occur in late spring through fall, although most damage occurs during June and July. Dollar spot is more prevalent in under-fertilized turf and in compacted soil with a thicker thatch layer. Typically, it looks like hour-glass shaped lesion with a dark border surrounding a whitened center, producing many 2-6 inch spots.
This fungus prevents roots from taking in water, oxygen, and nutrients. Mushrooms appear in bands or circles and can be from 3-50' in diameter. Grass often appears greener in affected areas. To get rid of this fungus, begin by stripping off any dead turf and replace infested soil before re-sodding. Sod will be tight and hard. Use a root feeder to soak nearby grassroots, starting about 2 feet away and working towards the infested area. Soak several times to ensure the roots of your new grassroots takes hold in the soil.
This is a fungal disease that attacks lawns that are highly exposed to the sun that are made up of either Kentucky bluegrass, red fescue, or bent grasses. Fusarium blight will cause small brown rings to appear in early summer. To remove the fungus, begin by heavily soaking your lawn and avoid frequent light soakings. Then, dethatch and apply lime treatments to your lawn to avoid acidic soil. Finish up by applying high-Nitrogen fertilizers.
Warm, humid days and cool nights favor mildew in bluegrass and fescues. The grass shows a gray-white, white, or brown mold on the leaf blades, often in shady areas with low air circulation and poorly draining soil. Avoid overwatering during hot humid weather and increase the amount of sunlight to the affected area.
Rust effects bluegrass, ryegrass, bermuda grass, zoysia, and tall fescue grass. Orange or red-brown blisters appear on the blades of your grass, causing it to wither and die. The blisters burst and the spores move on to infect healthy grass. In order to stop the spores in their tracks, mow the lawn as soon as it grows to a 1/2 inch and catch and remove all clippings.
Smut or Stripe Smut
Bluegrass and bentgrass are most affected by this fungus in cool spring and fall weather. Leaves develop black or gray stripes that rupture and discharge black spores infecting healthy grass. Diseased grass is stunted and begins to turn a yellow-green color while the leaves curl and shred before dying. To remove this fungus, seed your lawn with a blend of bluegrass seed that is more resistant to smut.