Plant Disease Management Handbook

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

Small, reddish brown spots girdle leaves, causing dieback from the tip.

Alec Kowalewski.

Small, reddish brown spots girdle leaves, causing dieback from the tip.

Alec Kowalewski.

Heavily infected stands turn yellow, then brown.

Alec Kowalewski.

Small, reddish brown spots on leaves.

Alec Kowalewski.

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Wheat (Triticum aestivum) - Nematode, Root-knot

Meloidogyne damage on course.

Emily Braithwaite,

Damage from Meloidogyne on golf course putting green.

Emily Braithwaite,

Microscopic view of Meloidogyne nematodes.

Emily Braithwaite, 2024.

Meloidogyne female erupting from infected swollen roots.

Emily Braithwaite, 2022.

Hosts Turf with strong rhizomatous-growth habit such as Kentucky bluegrass and fine fescue.

Image related to Lawn and Turf-Necrotic Ringspot

Kentucky Bluegrass with necrotic ringspot.

Melodie Putnam, 2010.

Necrotic ringspot on Kentucky bluegrass.

WSU Extension Plant Pathology Slide Collection.

Blackening of roots and rhizomes.

Melodie Putnam, 2010.

Dead circles and arcs are obvious during the summer months during periods of heat and drought stress.

Richard Smiley.

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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.

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.

Dieback due to Microdochium Patch on this Perennial Ryegrass turf.

OSU Plant Clinic collection, 2012.

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.

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,

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.

Note the circle of mushrooms in this lawn.

WSU Extension Plant Pathology Slide Collection.

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.