Vegetables, Berries, and Grapes: Root Rot

Problem
Leaves turn yellow, starting with the older, lower leaves and progressing to the younger ones. Plants grow very little. Flowers yellow and drop. Fruit shrivels and does not ripen. When the plant is pulled up, the roots are black, soft, and rotted. The soil has frequently been very moist.

Analysis
This plant disease is caused by any of a number of different fungi that are present in most soils. Some of these fungi normally do little damage, but can cause root rot in wet or waterlogged soil. Waterlogged soil may result from overwatering or poor soil drainage. Infection causes the roots to decay, resulting in wilting, yellowing leaves, flower and fruit drop, reduced fruit yield, and eventually the death of the plant.

Solution
To avoid root rot problems, do not overwater. Follow the watering guidelines under the entry for your plant in the index. Remove and destroy severely infected plants. Avoid future root rot problems by planting in well-drained soil. (For information on improving soil drainage, see Soil Types, Soil Structure, Groundwater.) Do not plant the same crop in a part of the garden where root rot was a problem in the past 3 to 5 years. For more information on root rots, see Water Molds.