At present, the most serius disease of banana in Sarawak is the Fusarium oxysporum f.sp.cubense.

Symptoms

The infected plant usually shows the yellowing of the leaves starting from leaf margins turning brown and dying progressively to the mid rib. Yellowing and dying of leaves starts on the older leaves; the dead leaves hang down at the side of the pseudostem. Then the whole plant dies when ifnection is so severe. Of the pseodostem is cut in cross-section, blakening of the xylem tissues can be observed (see photo).

How does the fungus infect the banana plant?

The fungus is soil-borne; it lives in the soil and gains entry into banana plants throug root wounds. It enters the water-conducting xylem tissues. The fungus produces spores that are carried upwards to the corm and the pseudostem. Hypae grow from spores and they block the xylem tissues effectively blocking the passage of the water and nutrients from the root system to the upper parts to the plant. The blockage causes the plant leaves to turn yellow, wilt and die.

Susceptibility of banana cultivars

The fungus that attacks banana consists of two races; Race 1 and 4. Race 1 infects most local banana varieties such as:

• Pisang Berangan
• Pisang Embun
• Pisang Rastali (Kling)
• Pisang Tanduk

Pisang Mas is reported to have some tolerance to the disease while Pisang Otel is known to be more relevant.

Race 4 of the pathogen threatens to infect most banana cultivars including Cavendish banana which is known to be resistant to Race 1 fungus.

How to control the Fusarium Wild in Banana?

No chemical found to effectively cyre the fungus and we should take measures to reduce it and possibly prevent it from occurring. These include the following six steps:

1. Plant banana cultivars that are known to be tolerant to the disease
2. If banana planting materials such as suckers are to be collected from the field, they should be collected only from gardens which are free of the disease. This is very important because the disease can be transmitted through infected suckers.
3. Avoid planting in area where the Fusarium wilt is known to occur. The fungus can live in the soil for up 20 years. Disinfecting the soil with chemical can be expensive and yet may not be effective.
4. Destroy infected plant and surrounding plants with weedicide. Do not remove the plant but burn it when it is dry.
5. If possible, restrict human or domestic animal's movement in the infected area. Put up barriers to movement so as to prevent of disease through soil particles carried by shoes or feet.
6. Sterilise the farm tools with disinfectant such as household bleaching solution (e.g.clorox) before using them in another garden.

Contribution: From Farmers Bulletin June 2002