Root Rot
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About this condition
Root rot is a physiological disorder in which roots decay due to waterlogging and poor drainage. Bonsai trees are particularly susceptible because of their shallow, confined containers; if left unchecked, the entire tree can weaken significantly.
Common symptoms
- Leaves wilt and turn yellow
- New shoot extension stops and the tree loses overall vigor
- Roots turn dark brown and feel soft when touched
- A rotting odor may be detectable from the soil
Common causes
- Excessive watering frequency
- Poor-draining growing medium or blocked drainage holes
- Chronic waterlogging during rainy seasons or prolonged rain
- High temperature combined with excessive moisture in summer
Prevention (growing conditions & routine care)
Water only when the topsoil begins to dry, watering thoroughly until it drains from the bottom holes. Use well-draining media such as akadama or kiryuzuna, and check drain holes regularly. Move trees under cover during prolonged rainy spells.
Related guide
→ Browse the species guide for this animalWhen to see a vet
Consider acting within a few daysWhat can a nursery or grower do?
Specialist bonsai nurseries and growers can advise on inspecting root condition, removing damaged roots, and repotting into well-draining growing medium suited to the tree species.
Related columns
- How to Choose a Bonsai Pot | The Basics of Matching Pots to Tree Species and Shape
- Leaf Pruning of Deciduous Bonsai (Hagari) — A Summer Technique to Promote Smaller Leaves and Finer Branching
- Beginner Bonsai: Year-One Growing Schedule by Species
- Bonsai Root Growth and Healthy Root System Development: Root Establishment Management and Repotting Timing
Other problems with this plant
Powdery MildewMonitor; consult a specialist if it worsensSooty MoldConsider acting within a few daysAphidsMonitor; consult a specialist if it worsensScale InsectsConsider acting within a few daysSpider MitesMonitor; consult a specialist if it worsensLeaf Scorch / Water StressMonitor; consult a specialist if it worsensBorer (Longhorn Beetle Larva)Act promptly (isolate, remove the cause)