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