The disease is most destructive in heavy clay soils that are saturated with water during cool weather when the fungus is most active. The red stele fungus can survive in soil for up to 13 years or longer once it becomes established in the field or garden. Symptoms When plants start wilting and dying in the lower portions of the strawberry planting, the cause is very likely to be red stele. Infected plants are stunted, lose their shiny-green luster, and produce few runners. Younger leaves often have a metallic, blueish-green cast.
Older leaves turn prematurely yellow or red.
With the first hot, dry weather of early summer, diseased plants wilt rapidly and die. Diseased plants have very few new roots, when compared with the roots of healthy plants that have thick and bushy roots with many secondary feeding roots. Infected strawberry roots usually appear gray, while the new roots of a healthy plant are yellowish-white. The most reliable symptom of red stele is found within the roots and may be observed by gently digging up a few plants that are just beginning to wilt, taking care to preserve the root system. During intermediate stages of disease development, these fleshy roots will be white near the crown of the plant but will show a dark rot progressing upward from the tips.