After an infection with Rhizome rot, single leaves start to turn brown. Starting with the heart leaves, the aerial plant parts wither and finally die off. Inside the root, you can find clearly delimited, red brown, rotten spots. These are causing the disruption of the plants water provision. The symptoms of Rhizome Rot appear in spring, very soon after blossom. Healthy plants growing in the immediate neighborhood of infected plants, which is typical for the disease. In warm spring weather, first losses appear after 4-6 weeks.
The Rhizome Rot pathogen is a fungus (Phytophthora cactorum) that can survive in the soil for years. Its zoospores depend on free water to spread and are be distributed by splashing water. Waterlogging is a common source of Root Rot fungus infection.
No direct treatment is possible. Apply preventive measures to avoid infection.
Always consider an integrated approach with preventive measures together with biological treatments if available. Apply Mefenoxam and Metalaxyl by drip irrigation to contaminated areas to prevent reinfections.