Presented at the Ontario Turfgrass Symposium, February 20, 2007. Guelph, Ontario, Canada.
http://www.uoguelph.ca/~thsiang/present/2007rhizoc_ots.htm

Update on Rhizoctonia diseases: what's the difference between brown patch, yellow patch
and yellow ring patch?

Tom Hsiang, Dept. Environmental Biology, University of Guelph, thsiang@uoguelph.ca

Presentation Objectives

North American Pests of Poa Survey

Rhizoctonia fungi

Rhizoctonia sclerotia

Rhizoctonia hyphae

Brown Patch (aka Rhizoctonia blight)

Rhizoctonia solani

Brown Patch on creeping bent green

Brown Patch on creeping bent green

Brown Patch on tall fescue

Brown Patch on tall fescue http://www.ces.ncsu.edu/depts/pp/notes/Turfgrass/Turf015/Figure1.htm

Brown Patch on perennial ryegrass http://www.aspresearch.net/brown_patch.htm

Brown Patch disease triangle

Pathogen: Rhizoctonia solani

Hosts: all cool season turfgrasses are susceptible

Environment: several days >25C, <35C, hi N, acidic soils, frequent watering, prolonged dew

Brown patch life cycle

Brown patch life cycle

Brown Patch: Infection
Hyphae of Rhizoctonia solani on epidermal cells, 3 days after inoculation.
Hofman TW & Jongebloed PHJ. 2005. Infection process of Rhizoctonia solani on Solanum tuberosum and effects of granular nematicides. Eur. J. Plant Path. 94:243-252. http://www.springerlink.com/content/j316094h896g71h2/

Brown Patch: Infection
Penetration peg of Rhizoctonia solani pulled away from penetration site, 4 days after inoc.
Hofman TW & Jongebloed PHJ. 2005. Infection process of Rhizoctonia solani on Solanum tuberosum and effects of granular nematicides. Eur. J. Plant Path. 94:243-252. http://www.springerlink.com/content/j316094h896g71h2/

Brown Patch sclerotia
http://www.bspp.org.uk/ndr/july2005/2005-60-2.jpg

Brown Patch: Diagnosis

Morning shade enhances infection

Brown Patch on Missouri lawn http://agebb.missouri.edu/news/pics/jj262.jpg

Brown Patch on creeping bent green

Brown Patch on creeping bent green

Brown Patch on creeping bent green

Brown Patch on creeping bent green

Brown Patch on creeping bent green

Brown Patch on fairway CB/AB

Brown Patch on fairway CB/AB

Brown Patch?

Brown Patch smoke ring

Brown Patch smoke ring

Brown Patch smoke ring

Brown Patch smoke ring

Brown Patch smoke ring
disappears when moisture dries

Brown Patch leaf lesions http://plantclinic.cornell.edu/FactSheets/brownpatch/rhizoc_grass_big.jpg

Brown Patch leaf lesions on fescue

Brown Patch: Control

Brown Patch: Fungicides

Yellow Patch (cool season brown patch) Rhizoctonia cerealis

Yellow Patch on KB, spring or fall

Yellow Patch Disease Triangle

PATHOGEN: Rhizoctonia cerealis

TURF SPECIES: All cool season turfgrasses

ENVIRONMENT: leaf wetness > 10hr, < 15 C, shade, lush growth, excessive fertility

Yellow Patch on KB, spring or fall

Yellow Patch on KB, spring or fall

Yellow Patch on KB, spring or fall

Yellow Patch on KB, spring or fall

Yellow Patch on AB & CB, Indiana

http://www.ces.purdue.edu/extmedia/BP/BP-118-W.pdf

Yellow Patch: Diagnosis

Yellow Patch: Control

Yellow Ring Patch (Sheath Blight)

Rhizoctonia zeae

Yellow Ring Patch

Yellow Ring Patch †

Yellow Ring Patch Disease Triangle

PATHOGEN: Rhizoctonia zeae

TURF SPECIES: All cool season turfgrasses

ENVIRONMENT: several days leaf wetness > 10 hr & highs > upper 20ís, shade, still air, watering in pm, high fertility (not limited by very high temperatures)

Yellow Ring Patch Control