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Lawn Management in Missouri: A Pathologist’s Perspective
Dr. Lee Miller Extension Turfgrass Pathologist
University of Missouri
1
HOST
ENVIRONMENT PATHOGEN
Amount of Disease
Disease Triangle 2
According to satellite imagery estimates, turfgrass has 3 times the acreage of corn: the most planted agronomic crop.
3
Grazing Point
Meristem
(Growing Point)
Stolon
Rhizome
4
Transition Zone 5
Bermudagrass, Zoysiagrass, St. Augustinegrass, Buffalograss
Bentgrass, Bluegrass, Fescue, Ryegrass
2 Choices 6
So What to Choose?
• Tall Fescue - Is the most popular for a reason. Good varieties for Missouri w/some brown patch resistance: (think art) Rembrandt, Picasso, Winning Colors (blend), Revolution (blend), RTF.
!
• LOTS of shade - Fine fescue (normally in mixtures of fine, red, chewings, etc.)
!
• Most costly establishment option - Zoysiagrass
7
“The picture is a sample of dead, moldy grass from a lawn!in Kirksville. The grass is a mix of bluegrass, bentgrass, &!perennial ryegrass. It was planted in May/June of this year.!It didn’t show any signs of distress until the 6” of rain we !received 10 days ago.
8
9
- Tredway
Tall Fescue/KBG MixturesTall Fescue/KBG MixturesTall Fescue
500 seeds/gramKentucky Bluegrass
4,800 seeds/gram
- Tredway
This means a 90:10 volume mixture is really
50:50 in # of seeds!!!
10
- Tredway, NCSU
Kentucky Bluegrass Can Take Over11
Disease Susceptibility
Tall Fescue Kentucky BluegrassBrown Patch Pythium
Pythium Summer Patch
Gray Leaf Spot Dollar Spot
Rust Leaf Spots/Melting Out
Red Thread
Pink Snow Mold
Powdery Mildew
Rust
12
HOST ENVIRONMENT
PATHOGEN
Amount of Disease
Disease Triangle 13
Disease Terms
Disease Definition: an abnormality in
structure or function caused by a
continuous association with an infectious
agent; injures the plant or reduces its
aesthetic value
Pathogen
Most turfgrass pathogens (> 90%) are fungi.
Chemicals that control diseases are called fungicides.
14
What Fungicides are NOT
• Herbicides - KILL PLANTS
• Insecticides - KILL INSECTS
15
What Fungicides Are...
• A chemical that destroys or inhibits fungal
growth.
• In fact, most do not kill the pathogen at all. They
merely arrest fungal growth.
• Many “fungi - stats”, not many “fungi - cides”.
16
Implications
• Fungicides are a temporary fix. The pathogen
and disease will be back.
• Fungicides need to be reapplied on regular
intervals (i.e. 21-28 d).
• Coverage is critical
• Fungicide resistance
17
Diseases on Cool Season Lawns
• Brown Patch - Particularly important to manage in fescue & fescue/KBG mixture lawns - EVERY YEAR !
• Pythium blight - In some years, this disease will “grab the baton” from brown patch and cause widespread damage. !
• Melting Out - Only seen on Kentucky bluegrass, particularly when stressed or mowed too low. !
18
Disease Susceptibility
Tall Fescue Kentucky BluegrassBrown Patch Pythium
Pythium Dollar Spot
Gray Leaf Spot Summer Patch
Rust Leaf Spots/Melting Out
Fairy Ring Red Thread
Pink Snow Mold
Powdery Mildew
Rust
Fairy Ring
2
21
3
4
19
• Appears in hot, moist overcast weather.
• Tall Fescue, Kentucky bluegrass
• High-cut grasses: patches are light brown and range from 2 feet to 5 feet in diameter. Grass is severely thinned.
• Distinct lesions on outer margins of patches. Tan with dark brown margins.
• Severe on highly fertilized lush grasses
Brown Patch 20
Brown Patch Diagnosis 21
Brown Patch Control
1. Reduce the duration of leaf wetness (Rhizoctonia requires ~ 9
hours of sustained moisture on the leaf).
2. Increase drainage.
3. Aerify to improve water infiltration, remove thatch.
4. Do not fertilize cool-season turfgrass too late in the spring.
5. Fungicides are best applied preventively if there is a history of
disease. QoIs/SDHIs longest residual, followed by DMIs.
6. New granular formulations.
!
22
Granular Formulations
• New influx of granular formulations hitting the market. !
• Aimed at the lawn market: considerable application advantages. !
➡ No specialized equipment - can use spreader !
➡ Spread in wider array of conditions (wind)!
➡ No need to lug around water tank door to door. !
!
23
0
5
10
15
20
25
% B
row
n P
atch
Sev
erity
Pilla
r GU
ntre
ated
Insi
gnia
+ T
rinity
Hea
dway
G
Hea
dway
Her
itage
+ B
anne
r
Her
itage
TL
Her
itage
G
7/31/12
Applications made on a 28 d interval starting May 22 . Columns with the same letter do not significantly differ according to the Waller Duncan k-ratio test (p=0.05, k=100).
(4 lb)
a
(4 lb)(3 lb)
24
Untreated Control Armada
Pillar G Headway G
25
Pythium
• Extremely hot & wet weather >90’s, heavy rains
• Primarily Kentucky bluegrass, but last year tall fescue
• Greasy matted appearance, dark brown
• Prevalent in shaded areas, and overwatered areas.
• Severe on highly fertilized lush grasses
26
27
28
Pythium disease control
1. Reduce the duration of leaf wetness (Pythium requires ~ 13
hours of sustained moisture on the leaf).
2. Increase drainage.
3. Aerify to improve water infiltration.
4. Do not fertilize cool-season turfgrass too late in the spring.
5. Phosphites/azoxystrobin can be used preventively.
6. Fungicides, if necessary, are in different classes than normal
fungicides. (ex. Subdue or Segway)
!
!
29
Brown Patch or Pythium? 30
Melting Out/Leaf Spot• Appears in hot, wet weather. Noticed
in late August/early Sept 2013.
• Kentucky bluegrass, perennial ryegrass (primarily on seedlings)
• Spotty at first, grass dies out in irregular areas in heavy outbreaks
• Pale white lesions with some dark black spots.
• Severe on highly fertilized lush grasses
• Most prevalent on low mow KBG
31
32
Melting Out Control
1. Reduce the duration of leaf wetness.
2. Increase drainage.
3. Aerify to improve water infiltration, remove thatch.
4. Do not fertilize cool-season turfgrass too late in the spring.
5. RAISE mowing heights.
6. Fungicides are best applied at the first sign of disease.
Preventive applications on seedlings may be necessary if
seeding in spring.
(Headway, Heritage, Curalan, 26/36)
!
33
• All like it hot.
• All are most damaging on seedlings and younger turf.
- Reason it’s best to seed in September instead of April.
• All are foliar, so reducing leaf wetness duration will limit the
disease epidemic.
• All three diseases greatly enhanced by lush, high nitrogen
turfgrass.
!
!
Pythium blight, Brown Patch, Melting Out
Common Threads 34
Dollar Spot
• Appears in mild - warm weather.
• Kentucky bluegrass, perennial ryegrass etc. etc.
• Most ubiquitous disease, infects a large number of hosts.
• Leaves are bleached white and straw color. Patches 1-6 inches or more across. Lesions are hour glass shaped.
• Severe on under fertilized grasses.
35
36
Dollar Spot Control
1. Reduce the duration of leaf wetness.
2. Increase drainage.
3. Aerify to improve water infiltration, remove thatch.
4. Fertilize in the fall, spring be careful.
5. Fungicides are best applied preventively or at the first sign of
disease. DMIs (Banner, Bayleton, Triton, Trinity, etc.),
Dicarboximides (Curalan), Benzimidazoles (3336)
6. Fungicide resistance is a concern.
!
37
Common Thread 38
Warm Season Turfgrass Diseases
Bermudagrass Zoysiagrass
Spring Dead Spot Large Patch
39
Large Patch
• Brown patch kissing cousin
• Infects zoysiagrass during fall and spring when growth is slowed down by cooler temperatures
• As name implies, large patches that may “fire” to orange margins when disease is active.
40
41
42
43
Large Patch Control
1. Reduce the duration of leaf wetness.
2. Increase drainage.
3. Aerify to improve water infiltration, remove thatch.
4. Be careful with fertilization too early in the spring or too late in the
fall.
5. Fungicides are best applied preventively in the fall or early
spring. DMIs (Torque, Triton etc.), QoIs (Heritage, Headway).
!
!
44
Chinch Bugs
Biology:
➡ Sucking mouth parts
➡ Gradual metamorphosis
➡ All nymphs suck plant juices
➡ White wings with triangular black markings
➡ Females lay 20 eggs per day for 2-3 weeks
➡ 1-2 generations per year
45
Damage: 20-25 nymphs/sq ft Monitoring: Sidewalks/Driveways, Coffee Can/Float, Hot day/Plastic Bag !
Damage is usually worse: ➡ Along sidewalks ➡ Curbs ➡ Driveways ➡ Cart paths ➡ Sunny locations
!Control:Curative - Pyrethroids
!!
Chinch Bugs 46
Hunting Billbugs
• Turfgrass species: Mainly Zoysiagrass (cv. “Meyer)
• Damage is often mistaken as:
➡ drought dormancy
➡ chinch bug or white grub damage
➡ dollar spot or large patch symptoms
!
47
Biology:
Dormant adults over-winter !Egg laying spring to early summer
Eggs deposited in leaf sheaths or in feeding punctures in stems
Eggs hatch in 3 to 5 days
Grubs eat there way down through stem and pop out rhizome. One to two generations per year
Hunting Billbugs 48
Hunting Billbug Control!• Damage may be masked by maintaining adequate fertility and
irrigation !Insecticides: ➡ Preventive - Site w/History
Pyrethroids for adult control in spring: Talstar - bifenthrin DeltaGard - deltamethrin Scimitar - lambda-cyhalothrin Merit - imidacloprid ➡ Curative
Combination Products: Allectus – bifenthrin + imidacloprid Aloft – bifenthrin + clothlanidin
Biological control: ➡ Steinernema carpocapsae nematodes
49
AprilMay
June July AugSept
Oct
Large Patch
Chinch Bugs
Hunting Billbugs
Recovery
Symptoms
Symptoms
The Zoysia Pest Timeline 50
HOST
ENVIRONMENT
PESTS
Amount of Disease
Disease Triangle 51
Integrated Disease Management
• Numerous factors can be manipulated to increase turfgrass health & reduce disease severity
- Moisture (Drainage & Leaf Wetness) - Temperature - Fertility - Shade - Organic Matter
• Fungicides should be last resort. Environmentally are much better than they used to be, but the bottom line is they cost $$$.
52
What do pathogens need to survive & cause disease?
• Water
• Temperature
• Host - preferably stressed out.
53
Columbia)Regional)Airport)(189072012) Top)3)Driest)May)1)–)Aug)19)periods 2012)))))))4.71” 1911)))))))5.12” 1936)))))))5.39”
0
5
10
15
20
25
30
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1890 1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
May
-Aug
Pre
cip.
(in.
)
May-Aug Precipitation Columbia, Missouri (1890-2012)
1993 1943
1995 1981
1901 1976 1936 2012
1990
1911
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Drought
July 30, 2013
US Drought Monitor - droughtmonitor.unl.edu
August 14, 2012
56
8/4/12 10/30/12
57
8/4/12 10/30/12 58
9/22/12 59
Drought Resistance Mechanisms
Escape ! Rapid development where plants complete their life cycle (go to
seed) before or during a water deficit. Poa annua
Avoidance ! Plants maintain high water potential by maintaining water
uptake or reducing water loss. Large root systems or adapted leaves with less stomata or stomata that close rapidly
Tolerance ! Low tissue water potential achieved by maintenance (or
suspension) of regular physiological processes. Dormancy in perennial grasses: 4-6 week grace period
60
Most Impacted Lawns
Cool season turfgrass lawns – particularly fine fescue shade mixtures and Kentucky bluegrass !Lawns that were watered inefficiently
Particularly early in the summer if irrigation was applied too frequently = short roots
!Lawns that were mowed during dormancy or too short
Not necessary !
Lawns with too much organic matter/thatch Holds water too high in the soil profile !
Lawns that were fertilized too late in spring/early summer More disease susceptible & favored shoot instead of root growth
61
Footprinting Due to Drought Stress 62
Thatch
63
2012 Calculations• Span 7/8 - 7/22: No rain - estimated 3.467” of water
lost to atmosphere (short crop evapotranspiration)
• Average lawn ~ 0.2 acres
• 1 acre inch = 27,154 gallons water; 3.467” lost = 94,143 gallons
• Need 13,180 gallons water for 70% ET replacement over average lawn.
• Golf course in STL: 300,000 gallons/day. Over average 100 managed turf acres, only 44% ET replacement.
64
Deep & Infrequent?
• In ground sprinkler systems: 39-51% adjusted sprinkler time seasonally, 16-24% never or rarely do.
• 65-83% of homeowners (in ground and non-) responded they didn’t know how much water they were applying to lawns.
• Water when lawn looks dry: Non-in ground: 52-60% In ground: 19-26%
Bremer et al, Kansas State Univ., 2012
65
- Tredway, NCSU
Kentucky Bluegrass Can Take Over66
Bermudagrass Zoysiagrass Tall Fescue
Kentucky bluegrass Perennial ryegrass
Fine fescues Low!
High!
Drought Resistance67
Bottom Line
• Consumers need to be better educated on drought impact on lawns and how to utilize irrigation.
• In extreme drought conditions, it’s often best to leave lawns dormant and not water. This is better than bringing it back and weakening it with inconsistent irrigation.
• Kentucky bluegrass is more drought susceptible than tall fescue. Lawns planted in mixtures of these 2 species may be more KBG, so identifying the host is important.
68
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0.00#
5.00#
10.00#
15.00#
20.00#
25.00#
30.00#
35.00#
40.00#
45.00#
1/1#
2/1#
3/1#
4/1#
5/1#
6/1#
7/1#
8/1#
9/1#
10/1#
11/1#
12/1#
Precipita
6on#(in
.)#
Date#
Columbia,#Missouri*#Annual#Accumulated#Precipita6on##Normal#vs.#2013#
30Iyear#normal#
2013#Accumulated#
*Columbia#Regional#Airport#
10.07"#surplus##thru#May#31#
26.71#inches#thru##May#31#
70
Too Much Water = Disease Cause #1
71
What do these have in common?
Reducing Leaf Wetness Duration for Foliar Disease Suppression
• Mowing
• Poling, whipping, dragging
• Tree pruning/removal
• Fans (also lowers air and soil temperatures)
• Irrigation timing
72
Early morning: 4 AM to 8 AM
• Evaporative losses minimized (Cooler temperatures)
• Better distribution of water (Calm winds)
• Knocks dew & guttation fluids off leaf blades and decreases leaf wetness period discouraging fungal growth and infection)
Irrigation - What Time of Day?73
Fertilization
Feed turfgrasses when they are actively growing!
74
Environmental Responsibility 75
Clean up after your fertilizer application by blowing/sweeping particles off of driveways or street gutters and back onto turf areas.
76
Nitrogen• Nitrogen (N)
–An adequate supply of N is associated with vigorous growth and deep green color.
–Turf that is deficient in N will result in: • Lack of turf density
• Stunted, pale green plants
• Reduced recuperative potential from pests and environmental stresses
–Turf has the ability to remobilize N from older tissue to provide N to younger tissue.
–Therefore, N deficiency symptoms will show up at the tips of older leaves first.
77
Nitrogen Deficiency Symptoms 78
Low nitrogen High nitrogen
Brown patch Pythium blight
Leaf Spot/Melting Out Spring dead spot
Large patch Gray leaf spot
Snow molds
Dollar spot Anthracnose basal rot Red thread Rust Pythium root dysfunction
!Key is don’t fertilize at the wrong time!!! !
Cool season - Nothing after May 1, fall fertilize in mid September!Warm Season - Only fertilize from May - August!
N Fertilization & Turf Disease 79
Nitrogen Timing
• Use the Oyster Rule
★ No fertilizing cool season
turf (longer cut) unless the
month has an “R” in it. !
★ Conversely, don’t fertilize
warm season turf in months
with “R”s.
80
Cool-Season Lawn Fertilization
• Common lawn care practice: Every 4-6 weeks. - Weed & Feed
• Heavy spring applications, and any summer applications lead to severe outbreaks of brown patch and Pythium
• Three applications a year max:
๏ Spring “Awakening”: 0.5 lb N (preferably with slow release forms: i.e. SCU) before May 1
๏ Fall “Recovery”: 1 lb N early - mid September
๏ Fall “Winterizer”: 1 lb N early - mid October
81
Cool-Season Maintenance Calendar82
Conclusions
• Use all of your resources to determine the cause of the problem -
including a diagnostic lab if necessary.
• Drought dormancy is not necessarily a bad thing. Consumers
should be made aware of irrigation practices that can enable the
plant to enter dormancy properly (i.e. Deep and Infrequent)
• Fertilizer application or overwatering during the summer may do
more harm than good.
83
http://extension.missouri.edu/main/
84
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Email List Serve Website
87
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When Things Go Wrong
1. Identify the problem!
2. Describe the problem - PICTURES!
3. Take precautionary measures!
4. Develop a list of possible causes!
5. Gather evidence!6. Eliminate possible causes!7. Select and implement a course
of action!
8. Evaluate effectiveness of selected action!
9. Repeat Steps 5 to 8 if necessary
89
Sample Submission
• Take pictures of symptoms and email to [email protected].!
• 1-2 Plugs per sample: square 2-4” on each side (each suspected problem)!
• Depth - only down to root zone, shake off excess soil!
• Wrap bottom in aluminum foil to stabilize; pack rest of box with newspaper or packing material; NO PLASTIC BAGS!!
• Ship overnight for best results.
90
No Need to Overdo It!! 91
Where to Take the Sample?
• For larger, patchy or ring symptoms that are larger than the cup
cutter, this is a critical aspect to obtaining a good diagnosis
• Too far in the middle of the patch has the least amount activity
of the true pathogen, and much more from opportunistic
pathogens
• Like mowing, use the 1/3rd rule: 1/3rd healthy turf, and 2/3rd
symptomatic turf
92
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Email: [email protected] Website: www.turfpath.missouri.edu
Phone: (573) 882-5623
Mizzou Plant Diagnostic Clinic95