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
Bentgrass Root Tip
n
o
i
t
a
g
lon
e
f
o
Zone
ic
t
a
m
te
Meris
n
Regio f cell
o
(zone n)
o
divisi
ap
C
t
o
Ro
Anatomy of a root
Region of elongation
Meristematic region
Root Cap
Value of core aerification
Root growth most
abundant in
aerification
channel where O2
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
Brown patch control
Untreated
Heritage
Heritage applied at 28 day intervals; UT Plant Science Farm
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 fungusLabyrinthula. 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