Fusarium wilt ("Mnyauko Fusarii" in Swahili) is a fungal disease of tomatoes. It causes yellowing and wilting of individual branches and leaves, but rarely entire plants. The disease starts with the lower, older leaves. The disease is often found on one side of a branch or plant. But later it spreads and can kill the plant. Most damage occurs on mature plants after flowering and at the beginning of fruit set, but seedlings can also be affected. Cutting into the stem at the base of the plant reveals a dark-brown to red discoloration due to the disease.
Fusarium wilt lives in the tomato plants and also in the seeds. It can therefore be spread by plant materials and seeds. The disease comes from the soil, and can survive for long periods in the soil or on other weed hosts. It is easier to prevent this disease than to control it.
To prevent the problem:
- Use non-infected clean seeds from healthy tomatoes, or certified seeds.
- Use tolerant/resistant varieties (e.g. Fortune Maker, Rio Grande, Tengeru 97, Roma VFN, Roma VF).
- Long crop rotations of 5-7 years would be needed to reduce the disease in the soil.
- Do not make compost and mulch from infected fields.
- Avoid injury of plants when working in the field.
- Sterilize tools and shoes in case fields are in a Fusarium infected area (e.g. with bleach, which is NaOCl). Wear gloves or wash hands with plenty water afterwards, because bleach is toxic.
- Do not use stakes from infected fields to stake tomato plants in disease-free areas
- If Fusarium wilt is detected in a part of your field, go to this area last after managing healthy plants.
- Avoid furrow irrigation because water can move this disease (if using furrow irrigation ensure that water flows from new to old fields).
When a single infected plant is found then actions should be considered.
- Remove and destroy entire diseased plant. But do not openly carry materials through your field, because this will spread the disease.
- There is no effective direct chemical control measure available.