Presentation on theme: "Pythium Root Rot/Pythium Root Dysfunction"— Presentation transcript:
1 Pythium Root Rot/Pythium Root Dysfunction caused byPythium graminicola, P. torulosum,P. vanterpoolii, P. myriotylum, P. ultimum,P. irregulari, P. rostratum, P. volutum andSeveral other species
2 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 iscaused by several other species of Pythium.The disease names Pythium Root Rot and Pythium Dysfunction arefrequently used interchangeably. It is uncertain at this time whetherthey represent 2 distinct diseases or refer to one common set ofsymptoms. Since signs, symptoms and control procedures are similarfor both diseases, I am considering them a single disease.
3 All turfgrass species are susceptible. Pythium Root Rot/Pythium Root DysfunctionSusceptible GrassesAll turfgrass species are susceptible.Cool season grasses are more susceptiblethan warm season grasses.Creeping bentgrass, perennial ryegrass, andtall fescue are most susceptible.
4 Favorable Environment - High root zone water content Pythium Root Rot/Pythium Root DysfunctionFavorable Environment- High root zone water contentlow oxygen in root zoneWide range of temps – Depends onwhich Pythium species is causingdisease.
5 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.
6 Leaf tip die-back frombentgrass with PythiumRoot Rot/Pythium RootDysfunction
7 Pythium Root Rot/ Pythium Root Dysfunctionthinning, stunting andyellowing of turfirregular patterndie-back of leaves fromtip down
8 Pythium Root Rot/Dysfunction (left) Note stunting of roots.
9 Pythium Root Rot/Dysfunction causes roots to be stunted but notdiscolored like Take-All Patch.
10 Pythium myriotylum masserates root tip Pythium myriotylum stained red in bent-grass rootPythium myriotylummasserates root tip
11 Healthy root tipTips of Pythium-infected rootsdisintegrate.
13 Pythium Root Rot/Dysfunction Management ofPythium Root Rot/DysfunctionResistant Species and CultivarsIn southeast U.S., creeping bentgrass is mostsusceptible turfgrass.High temperature-tolerant cultivars ofbentgrass e.g. Crenshaw, L93, A-1, A-4,G-2 may be less susceptible than othercultivars.
14 Pythium Root Rot/Dysfunction Cultural Control Management ofPythium Root Rot/DysfunctionCultural Control- Avoid high N applications in spring.Maintain moderate to high levels of P and Kaccording soil test.Improve surface and subsurface drainage.Core aerify every 3-4 wks. to enhance oxygenmovement into root zone.- Control nematodes.Decrease shade and increase air circulation.
15 Pythium Root Rot/Dysfunction Chemical Control Management ofPythium Root Rot/DysfunctionChemical ControlContract fungicides – ethazole, cyanofamid –7 to 10 days controlLocalized penetrant – pyraclostrobin – 10 to 14 dayscontrol.- Preventive treatments are better than curative.