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Root Rot

Root Rot

A close up of a rotted papaya trunk
Root Rot is a plant disease that can be caused by fungal pathogens and overwatering. Insufficient levels of light or fertilizer can also make some plants more susceptible to rotting. The most well-known rot-causing pathogens include Phytophthora, Pythium and Rhizoctonia. Because Root Rot occurs below ground, it often goes unnoticed until it's too late. Plants severely affected by rotting often can't be saved. To prevent Root Rot, always check the soil to see if a plant needs water beforehand. Likewise, if watering from the bottom up, don't allow plants to sit in water for too long.


Roots soften and die back - usually associated with a foul smell. Plants begin to wilt. Stunted growth. Black/ brown roots.


Wilting, yellow or sparse foliage
Branch dieback
Black/ brown roots
Poor growth
Development of cankers
Plants ooze sap
Infections can spread to the root and crown in severe cases

Biological treatment

Improving soil drainage can greatly reduce the risk of plants succumbing to the disease. Where the disease is new or localised in the garden, affected plants should be destroyed and the soil from the root-run replaced with fresh topsoil. Replanting should be done with less susceptible species. Depending on the severity, plants may recover. Remove the affected roots and lightly clean those which are still healthy. Make sure tools to remove the infected roots have been sterilised before use. Replant with fresh topsoil. Replanting will only work if plants with root rot are caught early enough. Any plant pots used should be cleaned and sterile.

Chemical treatment

Sterilise water in hydroponics/soil in pot plants.


Only water plants when the soil is bone dry. Always provide good drainage when planting. If watering houseplants from the bottom up, don't allow plants to sit in water for too long.

Affected plants


Acer spp.

A close up of some white Aesculus hippocastanum flowers and green leaves

Horse Chestnut

Aesculus hippocastanum


Buxus spp.


Ilex spp.


Lavandula spp.


Rhododendron spp.

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