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.