Disease Diagnostics - PrusaAssociates.com

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PrusaAssociates.com
[email protected]
© 2012 JG Prusa
© 2012 JG Prusa
Well…
before we get into diagnostics, let’s look at :
1. How do diseases of turfgrass develop?
2. What are ‘Life Cycles’ of pests such as turfgrass disease pathogens and why
must we study and know these life cycles?
3. What is Integrated Pest Management (IPM) – and why is it a ‘must do,’ Best
Management Practice (BMP) approach to what is now popularly called
‘sustainability?’
4. What are the potentials of detrimental impacts from applications of
chemicals that move into the soil biosphere and why must we use minimal,
precision intervention with powerful agricultural pharmaceuticals?
5. What is the importance of golf course operational hygiene and proper
equipment maintenance in pathology?
6. Why must we establish mandatory Chemical Applicator Technician Training
and Certification in modern Asia?
© 2012 JG Prusa
• Golf Course Superintendent
• Director of Education and first COO of the
GCSAA
• Golf Resort General Manager
• College Teacher – GCM and Hospitality Mgt
• Executive Director of Diving Equipment
Marketing Association (DEMA) and the
Business Technology Association (BTA)
• And a PADI Scuba Instructor
• NOW I DO WHAT I LOVE THE MOST!
• Bachelors Degree in Horticulture Science for
Cal Polytechnic University.
• MBA Program at Univ of Santa Clara
Graduate Business School
• Executive Program Stanford University
Graduate Business School
© 2012 JG Prusa
1. How do diseases of turfgrass develop?
• Many disease pathogens are actually beneficial
organisms – they are ‘saprophytic’ and referred to as
‘facultative.’
• Most disease pathogenic fungi are naturally in the soil
or organic matters – AND NORMALLY BENEFICIAL
• They are widely spread or inoculated into turf on seed
or from other native plant material – even previously
grown or adjacent crops (rice, sugar cane, cereal crops)
• Under certain conditions they facultatively become
‘parasitic.’ DISEASES
© 2012 JG Prusa
2. What are ‘Life Cycles’ of pests, such as turfgrass
disease pathogens, and why must we study and
absolutely know these life cycles?
• Waiting for visible symptoms to manifest is
too late.
• No spontaneous generation - Pasteur
© 2012 JG Prusa
3. What is Integrated Pest Management (IPM) – and why is it a
‘must do,’ Best Management Practice (BMP) approach to what
is now popularly called ‘sustainability?’
• IPM is a holistic approach to management
of pests
• Life cycles
• The 4 Ms of turfgrass management.
• Cultural practices – the rootzone
• Cutural practices – the surface
• Nutrient management
• Water management
• Environmental influences
• Stress / wear evaluation
• Scouting / monitoring
• Set $$$ threshholds
• Curative chemical intervention
© 2012 JG Prusa
4. What are the potentials of detrimental impacts from
applications of chemicals that move into the soil biosphere
and why must we use minimal, precision intervention with
powerful agricultural pharmaceuticals?
"To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour.“
“
“The Auguries of Innocence”
18th Century poet William Blake
© 2012 JG Prusa
4. What are the potentials of detrimental impacts from
applications of chemicals that move into the soil biosphere
and why must we use minimal, precision intervention with
powerful agricultural pharmaceuticals?
• Precise soil impacts have been researched, but tough to
study – biogeochemical complexities.
• Detrimental impacts vary, but they are generally agreed to
exist.
• Golf has around 5+ decades of experience dealing with
initiating sterile sand greens construction – we have
observed impacts. 3 years to achieve bio equilibrium!
• The biota of soils is very active and most organisms are in
the upper 15 cm.
© 2012 JG Prusa
4. What are the potentials of detrimental impacts from
applications of chemicals that move into the soil biosphere
(pedosphere biota) and why must we use minimal, precision
intervention with powerful agricultural pharmaceuticals?
Classification of soil biota:
• Microflora
• Plant roots, bacteria, facultative fungi, mychorrizae
• Microfauna
• Protozoa, mycophagous amoebae, bacteriovorus
nematodes, fungalvorus nematodes, predatory
nematodes
• Mesofauna
• Microarthropods: mites, collembola
• Macrofauna
• Macroarthropods, earthworms, enchaytraids
© 2012 JG Prusa
4. What are the potentials of detrimental impacts from
applications of chemicals that move into the soil biosphere
and why must we use minimal, precision intervention with
powerful agricultural pharmaceuticals?
What goes on within the biota?
• Disease transmission / infections
• Disease suppression / control
• Holding plant pest insects in check / balance (macro
and micro)
• Breakdown of organic matter
• Nutrient cycling (N, P, S)
• Organic matter turnover (stirring, mixing)
• Agrochemical degradation
• The biota is part of our food chain and it is inextricably
connected to our oceans!
© 2012 JG Prusa
5. What is the importance of golf course operational hygiene
and proper equipment maintenance in pathology?
• The same reasons apply as in medicine / hospital
• Disease transmission
• Mower sharpness is essential – just as is the edge of the
surgeon’s scalpel
• Pesticide application equipment
• Safety
• Application precision and efficacy
© 2012 JG Prusa
6. Why must we establish mandatory Chemical Applicator
Technician Training and Certification in modern Asia?
• It has been tried in two places in Asia
• Chiba Prefecture in Japan
• The Philippines
• Long established in advanced nations for good reason
• I.E. California
• Ridiculous to allow just anyone to obtain and apply
hazardous materials
• Precarious to health of individuals involved
• Staffs, golfers, neighbors
• Precarious to the nations involved
• Precarious to our terrestrial and oceans’ environment
NOW LET’S DO DIAGNOSTICS!
© 2012 JG Prusa
© 2012 JG Prusa
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Over watering probably kills more grass than all
diseases combined.
Overwatering contributes to disease occurrence and runoff.
Over watering saturates soil => anaerobic conditions => decreases gas
exchange (↓ O2 ↑ CO2) => ↑ carbolic acid in root cells => ↓ WATER
UPTAKE = ↓ NUTRIENTS! => weak or destroyed roots => ↑ WILT Not
heat from temperatures alone that kills grass, STARVATION KILLS THE
GRASS! A cascade of conditions from too much water.
Water is more dense than air and it conducts heat gain or loss 20 times
faster than air! (Physics of scuba diving)
Wasting fresh water is sinful – short supply.
Why the guessing game and inaccuracy on water?
© 2012 JG Prusa
USD $ 1,000+
= SGD 1,220
USD $ 5 = SGD 6.10
‘Sustainable’ Price
© 2012 JG Prusa
H2 O
• What is wilt?
• H2O water molecules are polarized and
soil
attract:
water
• H2O in the soil ranges from:
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© 2012 JG Prusa
Saturation
Field Capacity
Permanent Wilting Point
PWP = Wilt
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To learn more about water in soil and its
movement, go to my web site for this video:
www.PrusaAssociates.com/videos/WaterMovementInSoils.mp4
•
Roots DO NOT seek water – they simply grow in
favorable soil environment. [Research on radishes
demonstrates a tropic response induced by auxins in root tips.]
© 2012 JG Prusa
• Healthy turfgrass growth occurs between
the range of less than field capacity to slight
more than PWP.
FIELD CAPACITY (FC)
© 2012 JG Prusa
PERMANENT WILTING
POINT (PWP)
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Initial Symptoms of Wilt:
• Foot printing / leaves lay down
• Color change to darker or blue and gray tints
• Curling or rolling of turfgrass leaves
• Quick recovery after adequate water applied
• If left unattended:
• Desiccation of plant – leaves turn straw colored
• Die-back of root system
• Permanent damage, senescence, no recovery
© 2012 JG Prusa
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Causal agent:
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Bipolaris cynodontis (and other species of
genus – Bipolaris spp. Also Drechslera gigantea
on Bermuda and other Drechslera spp.)
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Optimum Conditions
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© 2012 JG Prusa
Wet, overcast and slightly cooler temperatures
In tropical regions, rainy seasons most optimum,
but will occur year round
Over fertilization ~~~~~ -------
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Manifest Symptoms
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© 2012 JG Prusa
Gray, tan, reddish brown, purplish, or black elongated
oval lesions on leafs
No symptoms manifest on crown or roots – unless very
severe outbreak that can appear as tissue rot
No fungal signs
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Manifest Symptoms
© 2012 JG Prusa
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Life Cycle
• Survives dryer cool cycles as
spores. Spores spread.
• Spores inoculate leafs (round
and brownish).
• With moisture the spores
germinate and the mycelium
penetrates leaf – the lesions.
• Conidia are fusoid in that the
width tapers at both ends –
produce conidiaspores
• Conidia tend to be curved.
• Have dark pigmentations.
© 2012 JG Prusa
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Manifest Symptoms
• Conidia are fusoid in that the width tapers at both ends –
produce conidiaspores
© 2012 JG Prusa
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Preventative Cultural Practice to Inhibit
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© 2012 JG Prusa
Dispose of debris / clippings
Clean mowers – SHARP MOWERS!
AVOID THATCH – leaf spots are facultative saprophytes
Avoid over use of N fertilizer – spoon feed at 0.5 to 1 g/
M2 per week (per your course needs)
Silicon (Si) has been shown to enhance Bermuda grass
resistance
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Preventative Cultural Practice to Inhibit
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Plant available Silicon (Si) has been shown to have a
relationship to resistance (Datnoff & Rutherford – USGA Funds)
Si is not a plant nutrient – BUT…
Quartz sand (SiO2) for greens show Si deficiencies
Applications of calcium silicate 39% improved resistance
2,000 kg Si / ha = 200 g / M2
2,000 kg Si / ha = 200 g / M2
80% ↑ Si in tissue
39% ↑
© 2012 JG Prusa
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Corrective Interventions
If an outbreak is extensive and damage will occur, then a foliar application of
an effective fungicide is required. An application every 14- 21 days is usual to
gain control. Please follow local registration lable for these products. This is
a partial list of fungicides that have been shown to be effective:
Mancozeb
Azoxystrobin
Thiram
Vinclozolin
Triadimenol
Iprodione + Thiophanate-methyl
• USE LOW WATER VOLUME APPLICATIONS
• ROTATE FUNGICIDES & Mode of Action
© 2012 JG Prusa
• Just as there are a few pathogenic organisms that cause
various leaf spots of similarity, so too are there a handful of
organisms that manifest damage to crowns and roots of
plants.
• For the most part, there are not neat, clear separations of
diseases into “crown” or “root” diseases. Both are impacted.
• Most of the warm season grass diseases in this group can
manifest damage to both the crowns and roots, depending on
conditions and stage of the life cycle – and they can also
impact leafs too!
© 2012 JG Prusa
• It is important to truly study and learn these turf diseases to
do accurate diagnosis.
• They commonly infect warm and cool season grasses
• The basic organisms we will quickly cover include:
• Take-All-Patch, Gaeumannomyces graminis var. avanea
• Bermuda Decline, Gaeumannomyces graminis var. graminis
Necrotic Ring Spot, Leptosphaeria korrae
• Pythium spp.
© 2012 JG Prusa
• Causal agent (very similar):
• Gaeumannomyces graminis var. avanea (Take-all-Patch)
• Gaeumannomyces graminis var. graminis (Bermuda Decline)
• First identified in Oklahoma, USA in the 50s & 60s
• Optimum Conditions:
• Heavy thatch and over-wet, stressed conditions in Zoysia
and Bermuda
• I have found EXTREMELY variable by turf species ‘variety’ or
‘cultivar’ - MORE LATER
© 2012 JG Prusa
• Manifest Symptoms:
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Circular patches in spring (equatorials – year round) when green up
or high growth period begins – center collapses
Root decline initially (in fall or as dormancy period approaches) with
no visible signs on surface until stress demands CHO from roots
(equatorials – year round)
Take samples
from active edge
© 2012 JG Prusa
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Life Cycle
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Not completely understood – especially in equatorial regions
© 2012 JG Prusa
Perithecia
and
Mycelium
Hyphae
© 2012 JG Prusa
SKY72 Korea
bent grass
greens
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Preventative Cultural Practice to Inhibit
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© 2012 JG Prusa
USE more resistant cultivars!
DO NOT allow thatch to build up
DO NOT over irrigate
Practice aerification methods
Keep soil pH in a range of 6.0 to 6.8 – acidic lowers severity
MAKE SURE you have adequate MANGANESE (Mn) levels in soil as there
seems to be a correlation – apply MnSO4(H2O) at 1 - 2 g / M2
New sand greens (and sand caps) very susceptible
Likely a SYMBIOTIC relationship with mycorrizhae
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Interaction with Mn levels
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Develop soil biota health !!
Avoid soil compaction
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Corrective interventions:
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Once damaging infections are present it will be necessary to apply
effective fungicides to suppress the disease.
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Normally these are only effective in the ectotrophic stage to
interupt the growth of hyphae and perithecia from speading
more inocullum.
© 2012 JG Prusa
•
Erratum:
Fall down, don’t
come back up!
© 2012 JG Prusa
Shizumi-Sho
ASK QUESTIONS!!
• Causal agent:
• Leptosphaeria korrae (Ophiosphaerella korrae)
• Optimum Conditions:
• Heavy thatch -- High pH -- Low Mn
• Over-wet conditions in Zoysia and Bermuda
• Manifest Symptoms:
• Small (15-20 cm), isolated circular ring patches in spring (equatorials
– year round) when green up or high growth period begins
• Root decline initially (in fall or as dormancy period approaches) with
no visible signs on surface until stress demands CHO from roots
(equatorials – year round)
© 2012 JG Prusa
• Symptoms
Pseudotheca = perithecium-like fruiting body
containing asci and ascospores
© 2012 JG Prusa
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Life Cycle
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Quite similar to Gaeumannomyces spp.
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Infects and spreads on roots mostly via mycelium
© 2012 JG Prusa
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Preventative Cultural Practice to Inhibit Disease:
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© 2012 JG Prusa
USE more resistant cultivars!
DO NOT allow thatch to build up
DO NOT over irrigate
Practice aerification methods
Keep equipment clean and mowers SHARP
Keep soil pH in a range of 6.0 to 6.8 – acidity lowers severity
MAKE SURE you have adequate MANGANESE (Mn) levels in soil as there
seems to be a correlation – apply MnSO4(H2O) at 1 - 2 g / M2
New sand greens (and sand caps) very susceptible
Likely a SYMBIOTIC relationship with mycorrizhae
•
Interaction with Mn levels
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Develop soil biota health !!
Avoid soil compaction
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Corrective Interventions (fungicides give incomplete control – key is
irrigation-fertilization-thatch control)
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© 2012 JG Prusa
Azoxystrobin (Heritage)
Fenarimol
Propiconazole
Thiophanate-methyl
Triadimefon
Myclobutanil
Provide adequate water to areas with a history of this disease
applying 2 to 3 cm (0.75 to 1 inch) of water several days before
applying the fungicide.
Water in after fungicide application (placement)
Follow label directions
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Causal agent:
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Pythium spp. (species not universally clear but seems to be the
same as Pythium aphanidermatum that infects cool season grasses)
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Especially impacting the new ultradwarf bermudas (UDBs)
Optimum Conditions
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Extended periods of cloudy / overcast wet conditions
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NOT A PROBLEM in dryer conditions
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Multiple-stressed, low-cut turf
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Excessive thatch
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Excessive fertilizer
© 2012 JG Prusa
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Manifest Symptoms
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Can often be confused with LEAF SPOT
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Rapid, purplish discoloration and decline
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Can also be dark green discolored
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‘Cottony’ aerial mycelium in high humidity –
NO SEPTA with Pythium versus others
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Leaf tissue becomes necrotic and turns
from purple to tan color
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Sunny and dry weather stops it
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Oospores spread with water or mowers like
all Pythium species
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In addition to foliar damage, it causes root
rot, crown and stolon damage
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Spores (zoospores) of Pythium are motile –
flaggela to ‘swim’ – avoid wet conditions
© 2012 JG Prusa
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Manifest Symptoms
Non-septated mycelium hyphae of
Pythium
Septa mycelium hyphae of Rhizoctonia solani
Brown Patch and note the acute, right angles
Septa mycelium hyphae of
Sclerotinia homoeocarpa Dollar Spot
and note NO acute, right angles
© 2012 JG Prusa
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Life Cycle
© 2012 JG Prusa
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Preventative Cultural Practice to Inhibit
• Avoid excessive thatch (another facultative saprophyte)
• Balance fertility and avoid erratic and excessive N
applications
• Avoid over irrigation – do best to keep surfaces
dry
• Avoid multiple stresses (compaction, wear, over / under
irrigation, over fertilization, shade, poor air circulation, etc.)
•
© 2012 JG Prusa
Hygiene is important – keep machinery washed,
clean and MOWERS SHARP!
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Corrective Interventions
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Fungicides of different groups and modes of action (systemic /
contact) should be rotated
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Always follow label instructions
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Azoxystrobin + Propiconazole
Fluoxastrobin + Chlorothalonil
Mancozeb + Myclobutanil
Propamocarb + Fluopicolide
Pyraclostrobin + Boscalid
Thiophanate-methyl + Chloroneb
• EXCELLENT LINK:
http://extension.umass.edu/turf/sites/turf/files
/images/common_fungicides_control_11.pdf
© 2012 JG Prusa
© 2012 JG Prusa

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