2. Brief introduction
Factors leading to epidemic
Symptoms
Disease cycle
Economic importance
Control measures
3. Brown patch is a disease of turf grass caused by
soil borne fungi Rhizoctonia solani
they are present in practically all soils throughout
the world and compose of a large number of
strains or races that attach to a wide range of
different plants including vegetables, flowers and
field crop
The disease is also known as Rhizoctonia blight or
sheath blight
Another species of fungus Rhizoctonia zeae is
more potent agent of brown patch that primarily
attack perrenial ryegrass and creeping bentgrass
on golf courses
4. nutritional category
The fungus itself is a necrotrophs as it release
toxins which kills the cell before it feeds on it
leading to appearance of lesions in infected
leaves
The fungus has a wide host range as it affects
turf grasses, flowers, vegetables and field crops
5. Brown patch usually develops on lawns during
periods of wet overcast weather in late spring
or fall
Damage is heavy after several days of showers
with day temperatures of 15-26 degree Celsius
Excessive nitrogen and thatch often leads to
outbreak of brown patch
High nitrogen promote growth of succulent
leaves that are susceptible to Rhizoctonia solani
6. Brown patch first appears in lawns as small
circular areas several inches in diameter which
quickly increase to 3-6 feet
Leaves first become water soaked, then wilt
and finally turn brown
On broadleaved turf grass like St Augustine
turf grass distinct tan coloured leaf spots
surrounded by soaked margins are sometimes
seen
7.
8. On tall fescue, symptoms of brown patch can
be observed on individual leaves and not
necessarily in patches.
Symptoms on leaves appear as irregular tan or
light brown lesions surrounded by dark brown
borders.
In severe cases, the entire stand may look
discolored and thinned
9.
10. Symptoms also appear as watersoaked and
dark purplish green colour “smoke ring”
This soon dries, wither and turn light brown
with dead leaves remaining upright
Algae often invade diseased patches and may
cause hard dark crusts
When attack is severe crown rhizomes, stolons,
roots turn brown and rot often killing large
areas
11.
12. Source of inoculum
Rhizoctonia solani fungus survive from year to
year principally in form of rounded brown
resting bodies called bulbis
The bulbis are found in thatch, diseased grass
tissue and top half inch of the soil
Bulbis are extremely resistant to heat, cold,
drought and fungicides
13. Germination
When conditions are favourable ie temperature
of 8-15 degrees celcius the bulbis germinate
Each bulbis germinate by sending out delicate
threads or hyphae in a radial pattern through
the upper soil and thatch
Penetration
The hyphae penetrates and infect grass plants
through leaf spores(stomata), directly through
leaf and stem or via mowing wounds
14. The fungus grows throughout the leaf tissue
growing up over the grass leaves and sheaths
The spread from one leaf to another occurs
through droplets of dew or guttation water
exuded at the leaf tip
Nutrients and organic compounds like amino
acid in guttation water stimulates fungus
growth
As long as the temperature is favorable, the
mycelium within grass clippings or thatch
resumes growth and initiates new infection
15. Overwintering
When conditions becomes unfavourable for
like air temperature reaching 35 degrees
Celsius the fungus sporulates
It forms a bulbis which may stay in soil for
many years in dormant state waiting for
availability of host and favourable
environmental conditions
16. Brown patch reduce quality and standard of
golf courses leading to loss of income to club
owners
Soccer stadium may not be recommended in
hosting international events like world cup
hence loss in foreign currency of a nation
17. Cultural method
Removal of dew or guttation water that collects
on the grass leaves each morning is an effective
aid in reducing brown patch
This can be achieved by dragging a water horse
across the area
Irrigation of the grass must be done during
midday leaving time for the grass to dry before
nightfall
18. Fungicides like Chipco 26GT is required on
high value bentgrass turfs
It is usually made on curative basis, the first
spray should be applied immediately after
onset of symptoms especially if prolonged hot
humid weather is expected
In areas were brown patch cause severe
thinning on putting greens, preventative
fungicide application may be justified
19. Clemson cooperate extension. 2013. Home and
Garden information centre:pdf available @
( http://www.clemson.edu/extension/hgic)
Krouse ,J.2011. Brown Patch:pdf. University of
Maryland , Symons hall. New Jersey
Landschout , P. 2010. Managing turf grass
disease:pdf. Pennsylvania State University,
available @ (agsci.psu.edu)