SPRING DEAD
SPOT
Causal Agent
Leptosphaeria korrae
Susceptible Turfgrass
Common couch grass, South African couch grass and their
hybrids
Symptoms
-
Circular patches of bleached, straw
coloured dead grass appear in Spring as the dormant grass
regrows.
-
Patches are also visible in autumn
and winter after a series of unusually cool days or wet, cold
weather.
-
Patches are a few centimetres to 1
m in diameter.
-
Patches reappear and expand in the
same spot for 3 or more years.
-
After 2 to 3 years, the centres of
active patches may remain alive, and the patch takes on a
"ring-like" appearance.
-
Roots of affected plants turn dark
brown to black and are severely rotted.
-
Regrowth of grass into affected
patches is slow and patches may remain barren of fill with
weeds.


Conditions Favouring
Disease
-
Most active when temperatures are
cool (12 C to 14 C) and soil is moist.
-
Roots of couch grow most rapidly at
24 C to 29 C and extremely slowly at 15 C, thus the fungus has a
competitive advantage at low temperatures.
-
Spring Dead Spot favours cool, wet
weather in the spring and autumn and daily temperatures of less
than15 C.
-
This disease is typically found
where thatch is more than 1.2 centimetres thick and in locations
with poor drainage and low potassium levels.
-
Heavy applications of nitrogen in
late summer often increase disease severity the following
spring.
-
Spring Dead Spot is more severe on
turf that is over three-years old and in locations with long
dormancy and cold temperatures.
General Comments
Distribution
All states of Australia