Fusarium wilt
A soil-borne fungus that blocks the water-conducting tissue, making plants yellow and wilt from one side.
Also known as: Panama disease (banana), Wilt
Symptoms and identification
Lower leaves turn yellow, often on one side of the plant first, then wilt even when the soil is moist. Cutting the stem near the base shows brown streaks inside. Plants decline and eventually die.
Causes
Fusarium oxysporum lives in soil for years and enters through the roots, especially in warm soil. It spreads with infected soil, tools, water and planting material.
Organic treatment
There is no cure once a plant is infected. Remove and bin affected plants with their roots and soil. Drench the area with Trichoderma and leave it free of susceptible crops for several seasons.
Prevention
Rotate crops, use resistant varieties, and plant in fresh potting mix in containers. Do not reuse soil from wilted plants, and mix Trichoderma-enriched compost into beds.
Chemical treatment (use with care)
Chemical treatments are of limited use. Soil solarisation (covering moist soil with clear plastic for 4–6 weeks in summer) reduces the fungus in beds.