Field Identification
Oomycete 'water mold' that rots seeds, hypocotyls, and fine roots in cold, saturated media—classic damping-off and stunted, yellow, wilted seedlings despite wet pots. Common where drainage is poor or irrigation runs continuously.
Roots turn honey-brown and slough the outer cortex; stem bases may be pinched and water-soaked. Microscopic ID separates Pythium from Phytophthora and Rhizoctonia.
How to Deal With It
Organic Control Methods
Copper, hydrogen peroxide, or potassium phosphite drenches where organic labels allow; biological fungicides with Streptomyces or Trichoderma as preventive drenches.
Gliocladium catenulatum (e.g., SoilGard) and Trichoderma products colonize rhizosphere competitively; Bacillus amyloliquefaciens strains used in some mixes.
Increase air porosity in mix; warm germination media; bottom heat; avoid overwatering; disinfect trays; use raised beds with French drains in field.
Pasteurize or solarize ground; improve subsurface drainage; use clean irrigation sources—not pond water loaded with zoospores without treatment.
Test reused mix; space plants for airflow; do not reuse flood tables without sanitation between crops.
Let Nature Handle It
Natural Enemies
- Trichoderma spp.
- Streptomyces spp.
- Gliocladium catenulatum
Threat Map