Pythium%20Root%20Rot/Pythium%20Root%20Dysfunction

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Pythium Root Rot/Pythium Root Dysfunction
caused by
Pythium graminicola, P. torulosum, P.
vanterpoolii, P. myriotylum, P. ultimum, P.
irregulari, P. rostratum, P. volutum and Several
other species
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Previously, we covered Pythium Blight, a foliar
disease caused by Pythium aphanidermatum and P.
ultimum. In this section, we will review Pythium
Root Rot/Pythium Dysfunction which is caused by
several other species of Pythium. The disease
names Pythium Root Rot and Pythium Dysfunction
are frequently used interchangeably. It is
uncertain at this time whether they represent 2
distinct diseases or refer to one common set
of symptoms. Since signs, symptoms and control
procedures are similar for both diseases, I am
considering them a single disease.
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Pythium Root Rot/Pythium Root Dysfunction
Susceptible Grasses

• All turfgrass species are susceptible.
• Cool season grasses are more susceptible
• than warm season grasses.
• Creeping bentgrass, perennial ryegrass, and
• tall fescue are most susceptible.

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Pythium Root Rot/Pythium Root Dysfunction
Favorable Environment

• - High root zone water content
• low oxygen in root zone
• Wide range of temps Depends on
• which Pythium species is causing
• disease.

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Pythium Root Rot/Pythium Root Dysfunction on
creeping bentgrass. Note irregular straw-colored
patches. Only foliar symptom is die-back from tip
of leaf downward.
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Leaf tip die-back from bentgrass with
Pythium Root Rot/Pythium Root Dysfunction
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Pythium Root Rot/ Pythium Root Dysfunction

• thinning, stunting and
• yellowing of turf
• irregular pattern
• die-back of leaves from
• tip down

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Pythium Root Rot/Dysfunction (left) Note stunting
of roots.
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Pythium Root Rot/Dysfunction causes roots to be
stunted but not discolored like Take-All Patch.
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Pythium myriotylum stained red in bent- grass root
Pythium myriotylum masserates root tip
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Healthy root tip
Tips of Pythium- infected roots disintegrate.
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Management of
Pythium Root Rot/ Pythium Root Dysfunction
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Management of
Pythium Root Rot/Dysfunction
Resistant Species and Cultivars

• In southeast U.S., creeping bentgrass is most
• susceptible turfgrass.
• High temperature-tolerant cultivars of
• bentgrass e.g. Crenshaw, L93, A-1, A-4,
• G-2 may be less susceptible than other
• cultivars.

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Management of
Pythium Root Rot/Dysfunction
Cultural Control

• - Avoid high N applications in spring.
• Maintain moderate to high levels of P and K
• according soil test.
• Improve surface and subsurface drainage.
• Core aerify every 3-4 wks. to enhance oxygen
• movement into root zone.
• - Control nematodes.
• Decrease shade and increase air circulation.

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Management of
Pythium Root Rot/Dysfunction
Chemical Control

• Contract fungicides ethazole, cyanofamid
• 7 to 10 days control
• Localized penetrant pyraclostrobin 10 to 14
  days
• control.
• - Preventive treatments are better than curative.

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End of Pythium Root Rot Section