Root rot is a plant disease caused by pathogenic water moulds (primarily Pythium and Phytophthora species) that attack and decompose plant roots in waterlogged or poorly oxygenated conditions. Affected roots turn brown or black, become slimy, and lose the ability to absorb water and nutrients.
Key Facts
- Primary pathogens: Pythium and Phytophthora water moulds, often pre-existing in water supplies
- Triggered by: insufficient dissolved oxygen, warm reservoir temperatures, and stagnant water
- Symptoms: brown/black slimy roots, wilting despite adequate water, yellowing leaves
- Prevention: maintain dissolved oxygen with air stones, keep reservoir below 20Β°C (68Β°F)
- Treatment: beneficial bacteria (Bacillus subtilis, Trichoderma) can suppress Pythium
- Hydrogen peroxide (3 mL of 3% per litre) can sterilise severely infected reservoirs