Plant Disease Management Handbook

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Living in the Land of Mosses

Algae, Lichens, and Mosses on Plants

Moss grows best and lawns grow poorly in shaded areas.

Jay W. Pscheidt, 2020.

Note the stripes of green moss in this lawn where an iron sulfate application with a fertilizer spreader did not overlap the previous pass leaving lines of living moss.

Jay W. Pscheidt, 2020.

Moss on the left was killed with an application of ferrous sulfate.

Jay W. Pscheidt, 2020.

Heavily shaded areas tend to have more moss than lawn.

Jay W. Pscheidt, 2020.

Image related to Lawn and Turf-Moss
Most of the green in this picture is due to moss and not grass.
Photo by Jay W. Pscheidt, 1995.

Hosts The disease is worse on annual bluegrass and tall fescue. Bentgrass, fine fescues, Kentucky bluegrass, and ryegrass (under high fertility) also can be infected but to a lesser degree.

Microdochium Patch on a Tall Fescue new lawn.

Brian McDonald, 2017.

Microdochium Patch in late winter on a putting green.

Brian McDonald, 2012.

Reddish brown circular patches (1 to 2 inches in diameter) of turf appear and may enlarge and coalesce to form extensive affected areas.

Brian McDonald, 2008.

White or pinkish fungal growth may be at the advancing edge of the patch.

Brian McDonald, 2011.

Image related to Lawn and Turf-Microdochium Patch (Pink Snow Mold)

Microdochium patch of Bent grass.

OSU Plant Clinic collection, 2012.
Image related to Lawn and Turf-Microdochium Patch (Pink Snow Mold)

Dieback due to Microdochium Patch on this Perennial Ryegrass turf.

OSU Plant Clinic collection, 2012.
Image related to Lawn and Turf-Microdochium Patch (Pink Snow Mold)

Note the yellowing older leaves.

OSU Plant Clinic collection, 2012.

This disease can occur under leaves before blowing them off. 

Brian McDonald, 2008.

Microdochium Patch on the left while Red Thread is on the right. 

Brian McDonald, 2016.

See:

Grass for Seed - Drechslera Leaf Blights (Helminthosporium Net Blotch)

Hosts Kentucky and other bluegrasses and perennial ryegrass.

Image related to Lawn and Turf-Leaf Spot
Drechslera leaf spot.
Photo by Carrie Foss, 1995.
Image related to Lawn and Turf-Leaf Spot
Leaf spotting fungi survive in the thatch layer.
Photo by Ralph S. Byther

Cause Nearly 60 different species of basidomycete fungi have been implicated in fairy rings including species of Agraricales and Gastromycetales, mostly in the genera Agaricus, Calvatia, Chlorophyllum, Clitocybe, Lepiota, Lycoperdon, Marasmius, Scleroderma,

Image related to Lawn and Turf-Fairy Ring and Mushrooms

Note the semi circle of mushrooms coming up in this sparse turf area.

Jay W. Pscheidt, 2005.
Image related to Lawn and Turf-Fairy Ring and Mushrooms

Note the circle of mushrooms in this lawn.

WSU Extension Plant Pathology Slide Collection.

Image related to Lawn and Turf-Fairy Ring and Mushrooms

A ring of mushrooms may be associated with living trees or places trees once stood.

Jay W. Pscheidt.

Hosts Most grass species are susceptible.

Cause Spores of the fungus-like organism Sclerophthora macrospora move via free water. The disease usually is associated with poorly drained or overwatered areas.

Leaves yellow and turn senescent.

Melodie Putnam, 2000.

Hosts Many cool-season species but a real problem on creeping bentgrass maintained at putting green or fairway height. This pathogen is also observed on annual bluegrass and perennial ryegrass, but to a much lesser extent.

Dollar spot on annual bluegrass.

Alec Kowalewski, 2021.

Dollar spot on creeping bentgrass. 

Alec Kowalewski, 2021.

Image related to Lawn and Turf-Dollar Spot
Dollar spot on perennial ryegrass in a home lawn in western Oregon.
Rob Golembiewski, 2011.
Image related to Lawn and Turf-Dollar Spot
Necrotic perennial ryegrass in a home lawn.
Rob Golembiewski, 2011.

Lesions occur near the middle of the leaf and extend completely across the leaf blade.

Richard Smiley.

Hosts Kentucky bluegrass is more sensitive than other types.

Image related to Lawn and Turf-Dog Injury
Dead grass due to dog urine.
Photo by Jay W. Pscheidt, 2002.

Photo by Jay W. Pscheidt, 2002.

Image related to Lawn and Turf-Dog Injury
Note the dead area of grass surrounded by darker green plants.
Photo by Ralph S. Byther

See:

Grass for Seed - Damping-off

Hosts Many. Ryegrass and bluegrass species are particularly susceptible to damping-off.

PNW Plant Disease Image

Damping-off caused this poor stand of Kentucky Bluegrass.

Alec Kowalewski.

PNW Plant Disease Image

Damping-off of Kentucky Bluegrass.

Alec Kowalewski.

Slide reads Fusarium crookwellense, which has been renamed to F. cerealis, from bentgrass.

Richard Smiley collection.

Hosts Common on bluegrass and fescue.

Cause Fungi, Curvularia spp., about nine species in all. They live on diseased grass and organic debris at the soil surface. The disease is most destructive in warm weather, from May to October and on compacted soil. These fungi are weakly virulent, commonly isolated from turf with problems and may be components of disease complexes.

Irregular reddish brown dead patches 2 to 3 inches in diameter appear.

OSU Extension Plant Pathology Slide Collection.

See:

Lawn and Turf - Yellow Patch

Hosts Annual bluegrass, creeping bentgrass, and rough bluegrass. The pathogen does not appear to affect perennial ryegrass, fescues, or Kentucky bluegrass.

Thin yellowing that can turn brown or necrotic.

OSU Plant Clinic image, 2011.

The fungus can colonize the foliage in affected areas.

OSU Plant Clinic image, 2011.

The fungus colonizes the foliage, crowns, upper roots, and thatch in affected areas.

OSU Plant Clinic image, 2011.