Pythium Root & Crown Rot

Pythium Root & Crown Rot - image 1

Causal Agent:

Pythium spp. (Pythium aphanadermatum, P. ultimum, P. irregulare)

Susceptible Crops:

Affects all turfgrass, Geranium, Poinsettia, Snapdragon


  • Young seedlings collapse shortly after germination or are severely stunted and appear nutrient deficient
  • Transplants and unrooted cuttings may develop a lower stem rot
  • Infections on established plants cause lower leaves to turn yellow and defoliate
  • Plants will wilt during the heat of the day, recovering at night
  • Infected roots are soft, brown with a water-soaked appearance. The outer portion of the root is easily removed, leaving behind the stringy vascular core of the root
Pythium Root & Crown Rot - image 2
Pythium Root & Crown Rot - image 3