You are here:
  1. Home
  2. Pests & Diseases
  3. Pythium


The genus Pythium contains many pathogenic species, such as P. ultimum, P. aphanidermatum and P. sylvaticum. Pythium species can cause soil-borne diseases in many hosts; they are generalists. They can attack several vegetables and ornamental plants. For example, cucumber, lettuce, chrysanthemum and poinsettia.

What damage can cause Pythium?

  • In propagation, it can cause seed rot and damping off of young plants
  • On mature plants, it infects roots and can cause stunting, root rot and crown rot

What are the characteristics of Pythium?

  • Pythium species form mycelium like fungi do, but they belong to a distinct group of microorganisms called oomycetes
  • Oomycetes can produce zoospores that can swim in water and infect roots
  • They also form oospores that are resting spores known to survive for months or years in soils
  • Pythium species are often found in soil, and also colonize very well the irrigation systems and growing media
  • They are very important pathogens in hydroponic crops
  • Contaminated transplants, water, dust and plant fragments on people and tools are source of Pythium inoculum
  • Fungus gnats and shore flies may also introduce and disperse Pythium in the greenhouses

How to protect plants against Pythium?

  • Avoid environmental conditions that predispose plants to Pythium. For example, high temperature in the substrate/water and low oxygen concentration in the root zone
  • Use growing media that promote microbial activity and, therefore, are more suppressive to Pythium
  • For biological control, apply the beneficial fungus Asperello T34 Biocontrol

Let's make things easier for you

We can offer you more relevant advice, if you let us know where you are and what language you prefer. Thanks!

PS: You'll only have to do this once (allowing cookies to remember your preferences).