Diseases of Bentgrass, Ultradwarf Bermuda and more Alan Windham Plant Pathology University of Tennessee
Abiotic Problems
Diagnosing Abiotic Problems Often associated with stress related to weather phenomenon May be related to cultural problems May be related to fertilizer or pesticide inputs
Abiotic (non-living cause of disease) What gives you a clue?
Signs or Symptoms Lack of signs or symptoms that would indicate a pathological problem point to an abiotic cause Nothing indicates that this is a disease No mycelium No fungal fruiting bodies No spores
Roots are healthy; foliage is bleached but no sign of fungal infection
Bentgrass roots stained with acid fuchsin; ; no sign of any root pathogens
Root tip is composed of: Root cap-protects root as it moves through soil Meristematic region where cell division takes place Zone of elongation where cells grow to their normal size
Root Cap Meristematic Region (zone of cell division) Bentgrass Root Tip Zone of elongation
Anatomy of a root Region of elongation Meristematic region Root Cap
Value of core aerification Root growth most abundant in aerification channel where O 2 level is highest.
Profile Problems Zone of high organic matter; often anaerobic; smells like a sewer; will not support root growth
Severe layering problem Black layer developing
Washed portion of plug; organic mat holds water and thus heat
Multiple black layers
Pathological root problems Pythium oospores stained with acid fuschin A pythium infection in the meristematic region can slow or stop root growth
Discolored roots + fungal structures = trouble Bentgrass root with a discolored center (stele) due to ETRI fungal infection
Root galls may = Root knot nematode A nematode infestation usually impairs root function and may lead to secondary problems from infections from other pathogens. Galls on bentgrass roots caused by root knot nematode
Root knot nematodes Root knot nema in root gall Female root knot
Root knot nematode eggs Female root knot nematodes may produce 300-500 eggs in egg masses
Anthracnose Caused by Colletotrichum cereale Grass is thinned Fungus visible on foliage, crown of plant Bentgrass
Anthracnose Setae- hairlike structures associated with fruiting bodies (acervulii)
Anthracnose Crescent shaped spores
Anthracnose Appresoria infection structures, visible in crown and root tissue
Anthracnose Infection mats Infection mats in leaf sheath
Rhizoctonia Diseases Brown patch cool season grasses Large patch zoysia and bermuda Yellow patch bentgrass Waitea patch- bentgrass, Poa annua
Brown Patch Warm weather disease of a cool season grass
Heritage applied at 28 day intervals; UT Plant Science Farm Brown patch control Untreated Heritage
Large patch This Rhizoctonia disease is active at green up on zoysia and bermuda
Yellow Patch White mycelium forms smoke ring Creeping bentgrass December 2007
Rhizoctonia cerealis Right angle branching
Waitea patch Described by Dr. Frank Wong, UC Riverside, on Poa annua
Southern Blight
Southern blight causal fungus Sclerotium rolfsii Occurs during very hot weather; fungus produces abundant white mycelium
Sclerotium rolfsii Fungus produces spherical structures called sclerotia (pl)
Southern blight-tall fescue
Pythium Diseases creeping bentgrass Poor color from pythium root decline Pythium blight- fungus has followed movement of water on green
Pythium blight of an ultradwarf bermuda? TifEagle
Pythium on Tifeagle Abundant white mycelium; also water soaked foliage
Pythium reproductive structuresoogonia
Rapid Blight Caused by a primitive fungus- Labyrinthula. Salinity usually is a problem when rapid blight shows up. Could be found on courses that use treated wastewater for irrigation source.
Labyrinthula cells dispersed when diseased tissue was macerated