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The maize lethal nucresis (MLN) which attacks mainly parts of eastern Uganda.
Symptoms
- Rot on the leaves, usually starting from the base of the young leaves in the whorl (funnel) and extending upwards toward the leaf tips.
- Mild to severe leaf mottling.
- Premature aging of the plants.
- Necrosis of leaf margins that progress to the mid-rib, resulting in drying up of the whole leaf.
- Necrosis of young leaves in the whorl before expansion, leading to a ‘dead heart’ symptom and death of the plant. Even though maize is reported to be the primary host of the MLN disease, a wide range of plants in the grass family (73 species) could be possibly affected by this disease.
Cause of the disease
The disease is caused by co-infection with two viruses, the sugarcane mosaic virus (group potyviridae) and maize chlorotic mottle virus (MCMV) (group tombusviridae). The MCMV is a new virus that had not previously been reported in Kenya.
Transmission of MCMV
The disease is reported to be spread by maize (corn) thrips, maize (corn) rootworms and leaf beetles.
Management
- Practise crop rotation for at least two seasons, with alternative non-cereal crops such as Irish potatoes, sweet potatoes, cassava, beans, bulb onions, spring onions, vegetables and garlic.
- Farmers should plant certified seed only and not recycle own seed.
- Diversification of farm enterprises by planting different crops each season.
- Remove infected foliar material from the field to reduce pathogen and vector population. This material can be fed to livestock.
- Grain and cobs that are rotten should not be fed to humans or animals. These are to be destroyed by burning.
- Use manure, basal, top dressing fertilisers to boost plant vigour.
- Plant maize at the onset of the main rainy season and not during the short rainy season so as to create a break in maize planting seasons. This will reduce the population of vectors.
- Use good field sanitation methods, including weed control measures to eliminate alternate hosts for potential vectors.
