Overview
- What pests affect the banana?
- Banana aphid
- Banana weevil
- Black sigatoka
- Banana skipper
- Cordana leaf spot
- Banana scab moth
- Root knot nematodes
- How do I manage banana pests?
- Summary
Bananas are the most produced and consumed fruit in the world. Approximately 20 million tonnes are produced annually, and the U.S. and India are major producers. Banana plants are vulnerable to many types of banana pests and diseases, which can impact fruit production and cause significant economic damage. This article focuses on banana pests and diseases that affect this crop, discussing approaches to combating these threats, including the use of biological methods.
What pests affect the banana?
Banana trees are impacted by a wide variety of banana bugs and diseases that attack different areas of the plant and cause specific symptoms. They are vulnerable to major insect pests, such as aphids and weevils, as well as the larval stage of moth and butterfly pests. Fungal banana plant diseases are also common and typically appear as dark areas on banana leaves. Damage can reduce yield and, in severe cases, cause complete plant loss.
Banana aphid (Pentalonia nigronervosa)
Banana aphid is a small insect that feeds on banana plants by piercing the plant tissue and sucking fluids with its mouthparts. Adults lay live aphid nymphs which progress through four developmental stages before maturing into adults. The early nymph stages are dark, reddish-brown, but become lighter in colour as they mature and grow to 1 mm in length. Adults are shiny and can appear black, dark brown, or reddish. Aphid damage can appear as deformed and discoloured leaves. They excrete honeydew, which can attract ants and promote the growth of black sooty mould.
Banana aphids transmit banana bunchy top virus, which causes bunchy top disease. Symptoms of the virus include leaf bunching at the top of the plant and dark streaks on the leaves and other plant areas. The fruit of infected plants is small, misshapen, and typically not suitable for sale.
Banana Weevil (Cosmopolites sordidus)
This banana insect, also known as the pseudostem weevil, banana root borer, or rhizome weevil, is a small pest that bores through leaves, stems, shoots, and roots of banana plants and feeds directly on banana plant tissue. Adults are black or reddish-brown and grow to between 1.3 and 2 cm in length and lay oval-shaped eggs in the pseudostem of banana plants. Eggs are translucent immediately after laying but turn yellow over time. It passes through five instar stages over 3 to 4 weeks before completing its larval phase and entering the pupal phase. Damage symptoms appear as leaf discolouration, stunted plant growth, and a jelly substance on the pseudostem due to larval burrowing. In severe cases, extensive burrowing is visible, leaves appear small, and banana fruit ripens prematurely.
Black sigatoka (Mycosphaerella fijiensis)
This is a fungal disease affecting banana plants. It is caused by a fungal species called Mycosphaerella fijiensis (Morelet). The fungus can spread as spores in water and by wind. It grows in warm and humid conditions and spreads across banana leaves before penetrating into the tissue. The disease is also called black leaf streak due to the characteristic horizontal dark brown and black streaks that it causes on infected leaves. Severe infections can cause leaf collapse and plant death.
Banana skipper (Erionota thrax)
This is a species of butterfly that attacks banana plants during its larval phase. Adults are brown with three characteristic yellow spots on their forewings. Males have a wingspan of up to 75 mm while females are slightly larger with a wingspan of up to 80 mm. Eggs are typically laid on the underside of leaves and hatch after about one week. The larval stage typically lasts about one month. Caterpillars grow up to 6 cm and are light green with a shiny black head. Adults emerge after a one-week pupal stage. Symptoms of banana skipper infestation include distinctive leaf rolls created by the larvae, which cut and fold the leaves to form a shelter where they later form the cocoon.
Cordana leaf spot (Neocordana musae)
This is a fungal infection caused by a species called Neocordana musae. The infection is also known as banana diamond leaf spot and causes black diamond-shaped spots to appear on banana leaves. The spots grow to about 10 cm in length and spread more rapidly in windy, wet weather. Spots are dark brown and bordered with yellow on the uppersides of leaves. The fungal spores grow on the underside of leaves, giving them a grey, hairy appearance.
Banana scab moth (Nacoleia octasema)
This species of moth causes severe damage to banana plants during its larval phase by feeding on the developing banana fruit. Adults are brown-grey in colour and have a wingspan of about 22 mm. Females lay up to 120 eggs in their lifetime. Eggs are about 1.5 mm long and hatch after 3 to 4 days. The larvae feed for about 10 to 20 days before entering a 10-day pupal stage. Damage appears as black and brown marks on the fruit’s skin. In severe cases, fingers appear deformed, and larvae can feed on the internal fruit flesh.
Root knot nematodes (Meloidogyne spp.)
The name “root-knot nematode” refers to a group of approximately 100 species of tiny worms that damage plant roots. Adults lay eggs that progress through four juvenile stages after hatching. During the second juvenile stage, these nematodes enter the root system of banana plants and feed on them. Above-ground, symptoms of root-knot nematode damage appear similar to those of drought, such as leaf yellowing and withering outer leaves. Beneath the soil, galls are a common characteristic, with root bifurcation (splitting into two) also occurring.
How do I manage banana pests?
There are several methods for managing pests that damage banana plants. A combination of approaches using integrated pest management practices and biological control methods often works well in many cases.
Monitoring
Watch carefully for the symptoms described above. Leaf discolouration, particularly black or dark brown spots, is the most common symptom associated with the pests we discussed. In some cases, pest damage may be easily visible, such as the leaf rolling of banana skipper larvae or the excessive burrowing of banana weevils. A high number of adult pests in the growing area can also indicate an infestation. Additionally, an increased presence of ants may suggest a banana aphid infestation.
Cultural control
Cultural control involves using specific farming or gardening practices to lower the risk of pest infestations. This method of crop management depends on correctly identifying the pest. Clearing the growing area of plant debris can reduce the number of pests like banana weevils. Many diseases thrive in wet conditions, so limiting irrigation may also be effective, as well as carefully removing infected leaves. Using clean planting material can be an effective way to combat root knot nematodes.
Biological control
- Natural Substances: These are typically derived from plants and can be used in sprays to repel or kill pests. For example, geraniol, which is found in plant oils like rose oil and citronella oil, can be effective in managing the banana skipper.
- Semiochemicals: These are messaging compounds that can be used to disrupt pest behaviour. For example, ECOSordidina contains banana weevil pheromones and can be used to lure this pest into traps.
- Microbials: These are microorganisms like bacteria, fungi, and viruses that harm pests but not crops. For example, Streptomyces lydicus is a species of bacteria that can help to combat root knot nematodes.
- Macrobials: These are larger animals, like certain insects, that feed on or parasitize pests. For example, Heterorhabditis bacteriophora is a beneficial nematode that can control root-knot nematodes. Steinernema carpocapsae is another beneficial nematode that can be used against the banana weevil.
Chemical pesticides
As a world leader in nature-based pest management knowledge implementation, CABI encourages Integrated Pest Management (IPM) as the preferred, ecologically-based approach to producing healthy crops, which allows for chemical pesticide use only as needed, and when adhering to measures that limit the exposure of people and the environment to them (see FAO, International Code of Conduct on Pesticide Management).
Before considering the use of chemical pesticides, farmers should explore all available non-chemical control solutions. These might include cultural practices like handpicking pests such as caterpillars, removing diseased plants, using resistant crop varieties, applying crop rotation and consulting the CABI BioProtection Portal for identifying and applying suitable biological control products (microbials, macrobials, natural substances and semiochemicals).
In case chemical pesticides are considered for use, farmers should look to select lower-risk chemical pesticides which, when used as part of an IPM strategy, help manage pest problems while minimizing harmful effects on human health and the environment. Agricultural advisory service providers can provide information on lower-risk chemical pesticides that are locally available and are compatible within an IPM strategy. These experts can also advise on the required personal protective equipment.
Summary
Banana crops are vital to global agriculture, including in India and the U.S. However, diseases and insect pests affect plant health and yields. Effective pest management, especially through monitoring, cultural practices, and biological control, offers a sustainable solution. Understanding and addressing these threats is essential to protect banana production and ensure long-term agricultural resilience.
For tailored pest management advice, visit the CABI BioProtection Portal, where you can enter your location and pest problem to explore customised solutions.
We have also prepared extensive guides on dealing with pests like fruit flies and protecting specific crops, including mango and coffee.
