Viola: Root and Stem Rot

Problem
Leaves turn yellow, wilt, and die. The roots and lower stems are soft and rotten. There may be white fungal strands on infected stems and around the base of the plant.

Analysis
This disease is caused by a number of different fungi that persist indefinitely in the soil. They thrive in waterlogged, heavy soils. Infection causes the stem and roots to decay, resulting in wilting, yellowing leaves, and the death of the plant. These fungi are generally spread by infested soil and transplants, contaminated equipment, and splashing or running water.

Solution
Remove dead and dying plants. It is important to allow the soil to dry between irrigations; root and stem rots are encouraged by waterlogged conditions. (For more information on this technique, see Water Molds.) Improve soil drainage. (For more information about soil drainage, see Soil Types, Soil Structure, and Groundwater.)