Strawberry Red Stele
Strawberry Red Stele  Strawberry red stele is a fungal disease caused by Phytophithora fragariae. Spores are released into the soil from decaying roots of infected plants. These spores can lie dormant for 12 or more years. Infection of healthy roots occurs in wet conditions. It is spread on contaminated plants, soil, tools, and boots. As summer approaches and soil temperatures rise, the fungus forms large numbers of oospores in the stele of infected roots. The fungus survives periods of hot, dry, or cold weather primarily as these oospores. Soil types do not affect the presence or absence of the red-stele fungus. It grows in any soil with a pH of 4.0 to 7.6, but will not grow in an alkaline soil (a pH of 8.0 or above). Heavy clay soils, which retain moisture for long periods of time, provide a fertile environment for the development of the red-stele disease because the zoospores can spread greater distances and produce more infection sites. Susceptible Plants- Strawberry Symptoms- Plants infected with strawberry red stele leaves develop a brownish purple tinge. A reddish band appears around the leaf edge; this may color the entire central leaf area. Growth can be patchy, with individual plants becoming weak and stunted. Roots are stunted and dark brown or black in color. The outer leaves of plants infected with strawberry red stele easily peel of. When to root is split open, the classic symptom is a red core running down the center. It is most notable in spring and autumn but less defined in summer. Plants infected with strawberry red stele lack vigor, are stunted, lose their shiny green luster, and produce few runners. The younger leaves often have a metallic, bluish green cast and older leaves turn yellow or red prematurely. During the hot, dry weather of early summer, infected plants wilt, collapse, and die rapidly. Infected plants that survive usually show symptoms in the late fall or the following spring. Prevention and Control- Always plant healthy certified stock. Make sure the growth site is well drained. Check with a reputable fruit nursery for suitable cultivars for your area. Do not grow strawberries on the same land again; spores the cause strawberry red stele can lay dormant for many years.
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