Identification and Management of Turfgrass diseases in Canada

Dr. Tom Hsiang

University of Guelph

email:  thsiang at


"recognize your enemy"

"known your enemy’s weaknesses"

Turf Disease Impact - HIGH
very frequent or very damaging or both

Moderate to High impact

may be damaging but less frequent

Turf Disease Impact - Low
generally less damaging

Snow molds (high impact)

Snow molds (high impact)

Gray snow mold (high impact)

Gray snow mold sclerotia

Sclerotia, survival structures

Sclerotium (plural: sclerotia)

Pink snow mold (high impact)

Pink snow mold ring (high impact)

Differences between snow molds?

Fusarium patch (high impact)

Yellow Patch (low impact)

Brown ring patch (new disease)
late spring/early summer (impact?)

Leaf spot (low impact)

Powdery Mildew (low impact)

Necrotic ring spot (moderate, root)

Take-all patch (moderate, root)

Summer Patch/decline (mod, root)

Necrotic / Take-all / Summer patch

Dollar spot (high impact)

Dollar Spot hourglass lesion (sablier)

Localized Dry Spot (moderate impact)
water just runs off, lots of thatch

Brown patch (moderate impact)

Brown patch (moderate impact)

Anthracnose foliar blight (high impact)

Anthracnose foliar blight acervuli

acervuli = hair-like structures

Anthracnose basal rot (moderate)

Anthracnose basal rot on Agrostis with acervuli in dead areas & rotted crowns

Pythium foliar blight (high impact)

Pythium foliar blight (high impact)

Pythium blight - hyphae on patches

Pythium root rot (high impact)

Pythium root rot (high impact)

Pythium root rot (high impact)

thick-walled oospores on root surface

Pythium root rot (high impact)

Rust (low impact)

Red thread (low impact)

Red thread (low impact)

Fairy ring - dead ring (low impact)

Fairy ring-stimulated ring (moderate)

Fairy Ring (Stimulated Ring) on CB

Fairy ring - mushroom ring (low)

Fairy ring - diagnosis

Algae (low impact)

Dog patch (moderate impact)

Take Home Information on diagnosis

Control of turfgrass diseases

Suggested control: water

Suggested control: thatch

Soil Micro-organisms

1 gram of soil contains thousands of bacteria & fungi

Role of these micro-organisms?

How well do cultural controls work?

What about biological controls?

Nontarget effects: Pest enhancement

Which fungicides can I use?

Search Product Labels (PMRA),17551&_dad=portal&_schema=PORTAL

Search Product Labels (PMRA),17551&_dad=portal&_schema=PORTAL

Search Product Labels (PMRA),17551&_dad=portal&_schema=PORTAL

Then which fungicide should I use?

Fungicide prices 2008 (dollar spot)

Fungicide prices 2008 (Pythium blight)

Fungicide prices 2008 (snow molds)

Are fungicides equally effective?
Dr. Paul Vincelli of the University of Kentucky provides an excellent list of turf diseases and rankings of fungicides (registered in the U.S.)    

  • Snow mold fungicides (OTRF funded)