Red Stele of Strawberry
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Red stele (Phytophthora fragariae) is caused by a soilborne, fungus-like water mold. Disease is more severe during wet weather or cool spring seasons. During early stages of root rot, plants may wilt during the heat of the day and then recover at night. As disease progresses, plants become stunted, lose vigor, and shed many older, weaker leaves. Lack of water uptake causes plant collapse and, if left untreated, plant death. Root rot develops from root tips and progresses toward lateral roots and crown. Roots cut lengthwise expose a red colored stele. Severely rotted root cortex results in sloughing off with stele remaining intact. The pathogen usually enters fields through infected plugs and tips, and can be spread through soil (tools, cultivation, shoes) and runoff water. This water mold can survive in soil for 15 to 20 years.
Red stele root damage.
(Photo: SCRI Scottish Crop Research Institute, Bugwood.org)
Reddened stele within infected root.
(Photo: John Hartman, University of Kentucky)
Management:
- Provide good internal drainage; manage water runoff.
- Use proper sanitation.
- Remove infected plants as soon as symptoms develop.
- Begin with clean plant material.
- Rotate with non-host crops.
- Use fungicides to suppress disease and reduce spread; fungicides do not cure disease.
