Pythium Disease Complex Flashcards
Pythium Host
All turfgrasses
Most pythiums cause…
root and crown disease
Pythium is in what Kingdom?
Stramenopiles
Pythiaceous “fungi” hyphae is..
aseptate
Pythium Blight symptoms
dead ass grass
Cottony blight
“grease spot” blackened turf
Pythium moves with…
Water
Mowing
Feet
Pythium Blight Predisposing Factors
• Hot weather – optimal +85F day / +70F night • Extended leaf wetness – +90% RH for >10 hours – poor air circulation – shade • Excessive nitrogen input • Seedlings • High seeding rates
Pythium grows from..
plant to plant
Pythium Blight Fertility Management
Balanced Fertility program
Adequate N inputs
-maintain growth
-avoid excess nitrogen, spoon feed
Pythium Blight disease management
KEEP IT DRY
Use irrigation judiciously; avoid drought, but
keep the foliage as dry as possible
• Improve drainage
• Prune trees to improve air circulation and
light penetration
• Mow when dry
• Use fans
• Aerify to reduce thatch and compaction
• Seed during cool weather
Pythium Chemical Class: phenylamides
mefenoxam, metylaxyl
Subdue Maxx,
Subdue
Pythium Chemical Class:QoI
azoxystrobin, fluoxastrobin
Heritage, Disarm
Pythium Chemical Class: aromatic hydrocarbons
ethazole
Terrazole
Pythium Chemical Class: QiI
cyazofamid
Segway
Pythium Chemical Class:carbamates
propamocarb
Banol, Stellar
Pythium Chemical Class:phosphonates
fosetyl-Al, phosphorous acid
Signature, Alude, Resyst
Pythium Chemical Class: benzamides
fluopicolide
Stellar
PB Chemical Control
• Use penetrants on preventive basis – get out in front of predisposing conditions • Use contacts for “short term” knockdown • Apron for seed treatment
Pythium Root Rot symptoms
irregular patterns, sometimes
in spots or patches, overall general thinning and
yellowing
Pythium Root most severe in…
well-drained greens
Will you see mycelium with Pythium Root Rot?
No
PRR Predisposing Factors
• Cool to- hot weather • Excess soil moisture − poor drainage − compaction • Poor site conditions − shade − poor air circulation • Collars and clean up areas
PRR - fertility management
• Maintain a balanced fertility program – soil test and adjust sufficiency levels of available nutrients as necessary • Maintain adequate N to inputs – maintain growth – avoid excess nitrogen inputs and succulent turfgrass
PRR - disease management
KEEP IT DRY!
• Use irrigation judiciously; avoid drought, but keep
the soil as dry as possible
• Prune trees to improve air circulation and light
penetration
• Use fans
• Improve drainage
• Aerify to reduce thatch and compaction
• Mow at recommended cutting heights
• Avoid mechanical damage and other stress factors
PRR – chemical control
• Preventive
– applications of cyazofamid, ethazole, mefanoxam,
or propamocarb preceding periods of wet weather
watered-in with 1/8” of irrigation to move product
into root zone
• Curative
– ethazole followed 3 to- 5 days later by a penetrant
(cyazofamid, mefanoxam, propamocarb) watered-in
with 1/8” of irrigation to move product into root
zone
Pythium Root Disfunction cause
Pythium volutum
PRD symptoms
Kills grass in spring
diffuse patches
thin patches in summer
PRD reduces
plants ability to absorb water and nutrients
PRD - predisposing factors
• root infection occurs during fall and spring
– 50 to- 75ºF soil temperatures
• roots die during heat and drought stress
• most severe on new construction
• other conducive conditions:
– low fertility input: especially nitrogen
– low mowing heights
– infrequent aerification: thatch, layering
PRD - fertility management
• Maintain a balanced fertility program – soil test and adjust sufficiency levels of available nutrients as necessary • Maintain adequate N to inputs – maintain growth – avoid excess nitrogen inputs and succulent turfgrass
PRD - disease management
KEEP IT DRY!
PRD - chemical control
• Rotation
– Insignia (0.9 oz, watered-in)
– Segway (0.9 fl oz, watered-in)
– Signature + Banol (4 + 2 oz) or Signature + Subdue
Maxx (4 + 1 oz)
• Preventative Schedule
– 21 to 28 days between applications when mean
daily soil temperatures are between 50ºF and 75ºF
• Curative Schedule
– 14 to 28 days between applications as needed
based on symptom expression
