Banana
Bunchy Top Virus
Bunchy Top Virus
Virus
In a Nutshell
- Dark-green streaks on leaves.
- Tiny dark green dots and dashes parallel to leaf veins.
- Stunted, slim and erect leaves with curled and wilted margins.
- Small green leaves form the plant crown.
Can also be found in
Banana
Symptoms
The virus can affect all plant parts at all growth stages. Initial symptoms can be mistaken for nutrient deficiency or physical stress and include the appearance of dark-green streaks on petioles, midribs and veins on the underside of new leaves. Later on, leaf laminae can also show these tiny dark green dots and dashes along the veins (called Morse code pattern). Affected leaves are stunted, slim and erect, and have curly and chlorotic margins that tend to turn necrotic. In advanced infections, new leaves show a worsening of these symptoms. The crown is characterized by the accumulation of small pale green or yellow leaves that form a "bunchy top. Overall growth is stunted and the plant may not produce bunches or fruits. If produced at all, fruits are deformed and small.
Recommendations
Organic Control
If the disease is spotted at early stages, spraying the plants thoroughly with soapy water or insecticidal soap can help to reduce aphid populations. Control chemical usage so as to maintain presence of natural enemies of aphids.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. There is no direct chemical treatment for viral diseases. Aphid populations can be controlled up to a certain degree with cypermethrin, acetamid, chlorpyrifos or related insecticides. In case of roguing plants in the field, treat them with power kerosene or insecticide to kill all aphids.
What caused it?
The symptoms are caused by a virus that is transmitted from tree to tree or between fields by the banana aphid (Pentalonia nigronervosa). Transmission over larger distances can occur via the carrying of infected planting material from one plantation to another. Further hosts of the virus include Ginger, Heliconia and Taro. Banana varieties differ in their susceptibility, the difference mainly shows in the time it takes for symptoms to appear. Plants do not recover from an infection. Primary infections through infected seedlings are generally worse than secondary infections via aphids. The symptoms are also exacerbated during the spring or during warm, dry weather.
Preventive Measures
- Only use healthy planting material from certified sources.
- Do not use planting materials from plants that exhibit symptoms.
- Grow more tolerant varieties, if available.
- Monitor plants regularly (every two weeks) and check for diseased plants.
- Remove infected banana plants, let them dry and bury them.
- Control volunteer plants or alternate hosts such as ginger, heliconia and taro.
- Create banana-free buffer zones between different plantations.
- Do not transport banana plants to different regions.
- Promote the presence of natural enemies of aphids (such as the ladybird beetle, chrysoperla, syrphid fly, and spiders) by reducing the amount of chemicals used in the plantation.
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