Strawberry Disease - Black Root Rot

This complex is associated with a number of pathogenic soil fungi (most commonly Rhizoctonia and Pythium species) and root-infecting nematodes; environmental conditions that can include drought, winter injury to the root system, and the freezing or waterlogging of the soil; herbicide injury; or a combination of all these factors. Older plantings or replanted areas are most commonly affected.

Symptoms and Disease Cycle

Symptoms include an uneven, "patchy" appearance in the strawberry bed. The first evidence of infection is the appearance of brown areas on the normally white or tan roots. Eventually, death of the feeder rootlets will result, and the structural roots of the mother plant will blacken and deteriorate.  Affected plants become stunted and produce few berries and runners. 

Disease Management

The disease is generally associated with high-clay soil types. Planting in well-drained, well-aerated soils such as those with a high organic matter content (greater than 3 percent) is strongly recommended. Soil compaction and excessive irrigation should be avoided. Mulching to reduce winter injury, purchasing disease-free plants, and leaving 3 to 5 years before replanting strawberries on the same site are methods for controlling black root rot. There are no fungicides for control.