Root Rot

 Too much of a good thing can be a bad thing.


And this is especially true when it comes to water in the soil. Over-watering and poor drainage often result in root rot, especially in houseplants. Once root rot occurs, the plant is doomed. ​

Plant suffering from root rot (Scot Nelson) Public Domain

How does root rot occur?

Heavy rains, flooding, and poorly managed sprinklers can lead to water stress just as easily as drought. Water-stressed plants quickly become susceptible to pests and diseases they would usually be able to handle on their own.


​A healthy plant breathes through its leaves and roots. When soil is too wet, the macropores and micropores become saturated. These tiny pockets within the soil hold and move water and air. If they are full of water, air can’t get in, and the roots cannot breathe.


At the same time, spores of mold and fungal diseases, such as crown rot, thrive in this soggy environment, replicating exponentially and clogging vascular bundles. When the xylem and phloem are blocked, plants cannot rid themselves of all that excess moisture. And the food from the leaves cannot reach the roots, resulting in death by starvation and asphyxiation.


​Symptoms of root rot

There are several types of root rot. The most common are Armillaria root rot, avocado root rot, black root rot, and Fusarium crown and root rot. Their symptoms are very similar.


One sign of root rot is the presence of fungus gnats. These tiny black, flying insects love to eat decomposing organic matter. Wilting is another common symptom of root rot. Leaves may turn red, purple, or yellow. You may also notice darkened areas in the bark at ground level. If you peel the outer bark away, you may see reddish-brown streaks within the inner bark.

Pythium root rot (Scot Nelson) Public Domain

Preventing root rot

Since root rot will kill your plants, prevention is paramount. These tips can help:

• Never cover a graft union with mulch or soil.
• Plant trees at the proper depth.
• Select resistant varieties.
• Monitor susceptible plants closely.
• Maintain good soil porosity.
• Allow the soil to dry out between waterings.
• Make sure sprinklers do not spray tree trunks.

Water is a precious resource, and there is no sense in wasting it, especially when it threatens the health of your plants. You may be surprised at how little water plants need.