Banana

Introduction

Moko disease is a bacterial wilt that affects banana and plantain crops. It's caused by Ralstonia solanacearum (formerly Pseudomonas solanacearum), which is a soil-borne pathogen. This disease is highly destructive and has been responsible for significant losses in banana-producing regions, particularly in Latin America and the Caribbean.

History

1901:

The disease was first identified in Trinidad, in the Caribbean, where it affected bananas and plantains.

It was initially not well understood but quickly became recognized for the severe wilting it caused in infected plants.

The term "Moko" is believed to originate from the indigenous word for banana in the Caribbean, specifically from Trinidad, where the disease was first identified.

Symptoms

Wilting: The leaves of the banana plant start to wilt, beginning with the younger ones. They eventually turn yellow and collapse.

Fruit symptoms: Infected fruits may show uneven ripening or internal browning.

Stem signs: Dark brown to black streaks can appear in the vascular tissues of the pseudostem and fruit stalk.

Plant death: In severe cases, the whole plant may die rapidly.

Spread

The bacteria are mainly spread through contaminated soil, water, tools, and planting material. Once the plant is infected, it can spread internally through the plant's vascular system.

Control and Management

Hygiene: Regular cleaning of tools and equipment to prevent the spread of the bacteria.

Use of disease-free planting material: Ensuring that only certified, disease-free plants are used for cultivation.

Field management: Avoiding movement of soil or water from infected areas.

Crop rotation: Planting non-host crops to help reduce the bacterial population in the soil.

Early detection and removal: Prompt removal and destruction of infected plants to prevent the disease from spreading.

Resistant cultivars

Wild Relatives and Landraces:

Some wild banana species and traditional cultivars have exhibited partial resistance or tolerance to Moko disease. These include certain Musa balbisiana species, which are naturally more resistant due to their genetic makeup.

However, these species or landraces are not typically used for large-scale commercial production because they often have characteristics, such as poor fruit quality, that make them less desirable for consumption.

FHIA Varieties:

The FHIA (Fundación Hondureña de Investigación Agrícola) breeding program has developed several hybrid varieties that show some resistance or tolerance to diseases, including Moko.

FHIA-17: A hybrid banana that has some tolerance to Moko disease, though not full resistance.

FHIA-23: Also bred for disease resistance, this variety has shown promise in managing diseases like black Sigatoka and has some level of tolerance to bacterial wilt diseases.

Biotechnology and Genetic Engineering:

Researchers are exploring genetic engineering to introduce disease-resistant genes into banana plants. This involves identifying specific genes that can protect against bacterial wilt and inserting them into commercially viable banana cultivars.

There are ongoing efforts to explore gene-editing tools like CRISPR to enhance resistance.

Cultural Practices to Enhance Resistance:

Although true resistance in most commercial varieties is limited, farmers can adopt integrated pest management (IPM) techniques that help reduce the likelihood of infection. This includes maintaining field hygiene, using clean planting materials, and carefully managing irrigation to limit waterborne spread of the pathogen.

Use of Endophytes:

Some studies have explored the use of beneficial microbes, such as endophytes, which live inside plant tissues. Certain endophytic bacteria or fungi have shown potential in enhancing plant defenses against pathogens like Ralstonia solanacearum. These could eventually be used as biological control agents.

Developing and implementing resistance strategies remains an ongoing effort in agricultural research, as managing Moko disease is essential for maintaining the global banana supply.

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