Plantwise Factsheets for Farmers
Control of cassava mosaic disease by uprooting
African cassava mosaic virus
Recognize the problem
Cassava mosaic disease is a plant virus that reduces cassava production. It is called Batobato ya muhogo in Kiswahili. The disease causes curling of leaves and the formation of yellow-greenish or white-greenish patches within the green leaf which is known as chlorosis or mosaic. When the disease is severe, the new leaves are small and distorted and the plants become stunted. Totally yellow leaves of normal size or brown leaves are not a sign of this disease. Wild cassava (kisamvu cha mpira in Kiswahili) also hosts the disease.
Cassava mosaic virus disease is a viral disease which is carried by insects such as whiteflies. When the whiteflies suck sap from the plant, they pick up the virus, and then transport and inject it when feeding on the next plant. To avoid the spread of the disease to healthy plants, the infected plants must be uprooted and destroyed. There is no agrochemical that can control the disease.
- Do not plant cassava close to infected fields as the insect vectors will transport the disease to healthy plants
- Keep the insect vectors that carry the disease away from the field by surrounding it with a clear boarder of no vegetation (2 to 3 metres wide). Slash all bushes.
- Observe plants for disease symptoms once a week for the first 2 to 3 months after planting. When 2 to 5 plants with disease symptoms are found in your field, prepare for uprooting process.
- Prepare healthy cassava cuttings which will be used to replace the diseased cassava plants
- The length of each cutting should be 15 to 20cm
- The uprooting process of diseased plants starts 2 to 3 weeks after the previously planted cuttings have sprout
- Two people should be involved, with one person searching and uprooting the diseased plants while the other person plants new healthy cassava cuttings. The uprooting person should not touch the new clean plantings and the planting person should not touch the diseased plants.
- Uproot diseased plants once every week by pulling them out by hand
- The uprooted plants should be carried away from the field and exposed to the sunlight for drying and then burned to kill the viruses. Do not bury the diseased materials in a field.
- The number of diseased plants is reduced as the exercise is repeated
When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.
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