Pythium Disease Complex

Question 1

Pythium Host

Answer 1

All turfgrasses

Question 2

Most pythiums cause…

Answer 2

root and crown disease

Question 3

Pythium is in what Kingdom?

Answer 3

Stramenopiles

Question 4

Pythiaceous “fungi” hyphae is..

Answer 4

aseptate

Question 5

Pythium Blight symptoms

Answer 5

dead ass grass
Cottony blight
“grease spot” blackened turf

Question 6

Pythium moves with…

Answer 6

Water
Mowing
Feet

Question 7

Pythium Blight Predisposing Factors

Answer 7

• 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

Question 8

Pythium grows from..

Answer 8

plant to plant

Question 9

Pythium Blight Fertility Management

Answer 9

Balanced Fertility program
Adequate N inputs
-maintain growth
-avoid excess nitrogen, spoon feed

Question 10

Pythium Blight disease management

Answer 10

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

Question 11

Pythium Chemical Class: phenylamides

Answer 11

mefenoxam, metylaxyl

Subdue Maxx,
Subdue

Question 12

Pythium Chemical Class:QoI

Answer 12

azoxystrobin, fluoxastrobin

Heritage, Disarm

Question 13

Pythium Chemical Class: aromatic hydrocarbons

Answer 13

ethazole

Terrazole

Question 14

Pythium Chemical Class: QiI

Answer 14

cyazofamid

Segway

Question 15

Pythium Chemical Class:carbamates

Answer 15

propamocarb

Banol, Stellar

Question 16

Pythium Chemical Class:phosphonates

Answer 16

fosetyl-Al, phosphorous acid

Signature, Alude, Resyst

Question 17

Pythium Chemical Class: benzamides

Answer 17

fluopicolide

Stellar

Question 18

PB Chemical Control

Answer 18

• Use penetrants on preventive 
basis – get out in front of 
predisposing conditions 
• Use contacts for “short term” 
knockdown 
• Apron for seed treatment

Question 19

Pythium Root Rot symptoms

Answer 19

irregular patterns, sometimes
in spots or patches, overall general thinning and
yellowing

Question 20

Pythium Root most severe in…

Answer 20

well-drained greens

Question 21

Will you see mycelium with Pythium Root Rot?

Answer 21

No

Question 22

PRR Predisposing Factors

Answer 22

• Cool to- hot weather 
• Excess soil moisture 
− poor drainage 
− compaction 
• Poor site conditions 
− shade 
− poor air circulation 
• Collars and clean up areas

Question 23

PRR - fertility management

Answer 23

• 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

Question 24

PRR - disease management

Answer 24

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

Question 25

PRR – chemical control

Answer 25

• 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

Question 26

Pythium Root Disfunction cause

Answer 26

Pythium volutum

Question 27

PRD symptoms

Answer 27

Kills grass in spring diffuse patches thin patches in summer

Question 28

PRD reduces

Answer 28

plants ability to absorb water and nutrients

Question 29

PRD - predisposing factors

Answer 29

• 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

Question 30

PRD - fertility management

Answer 30

``` • 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 ```

Question 31

PRD - disease management

Answer 31

KEEP IT DRY!

Question 32

PRD - chemical control

Answer 32

• 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