Banana Production Kit: Major Banana Diseases Caused by Bacteria

1. Moko/Bugtok (Bacterial Wilt)
This is a major disease of banana. Filipino farmers wait for 18 to 21 months to harvest cooking banana Saba (ABB/BBB), only to find out that 80 percent is bugtok infected.

Cause
Caused by the aerobic bacterium Ralstonia solanacearum (race 2) – syn.  Pseudomas solanacearum

Transmission

Moko

1. Infection is via roots or rhizome.
2. Soil to root transfer is slow but may be hastened by the presence of excess water in the field.
3. Mechanical transmission through contaminated tools during pruning, desuckering, removal of male buds or damaged leaves (wounds in: roots, rhizomes, male buds, leaves).

Internal symptoms of Moko and banana blood disease in healthy-looking unripe fruit.

Bugtok

1. Infection via insect vectors via male bud of cooking banana cultivars.

Symptoms
Moko

1. Yellowing and wilting of oldest leaves.
2. Oldest leaves become necrotic and collapse.
3. Younger leaves develop pale green or whitish panels.
4. Younger leaves become necrotic.
5. Suckers may wilt, without foliar symptoms.
6. Fruit development is arrested.
7. Fingers may ripen prematurely or split.
8. Internally, fruits become discoloured and eventually rot.
9. Pockets of dry gelatinous greyish black or yellowish red tissues in the fruit.
10. Vascular tissues become progressively discoloured.
11. Bacterial ooze exuded from vascular tissues, when cut.

Bugtok

1. First symptoms in flowers, buds and peduncles, which become blackened and shriveled.
2. Bacterial ooze may be observed at the base of the bracts where localized blackening may also occur.
3. If male flower is removed, external symptoms may not be observed.
4. Bacterium spreads to fruit, which may ripen prematurely and rots.
5. Infection continues to pseudostem, causing blackening of the vascular tissue.

Prevention and Control
There is no cure, so early detection and prompt eradication of infected mats is your only option.

1. Prevention, Eradication and Quarantine Measures

• Use clean materials in uninfested soil in starting a new banana plantation.
• Once an infection has been identified, eradicate diseased plant and quarantine the area.

1. Eradication can be done by injecting a herbicide (glyphosate) or by completely cutting and digging out the diseased plant.
2. Vampire method: The mother plant is cut down, bamboo sticks (15-20 cm long with shiny part removed) are soaked in 100% glyphosate for 24 hrs and inserted in the trunk of the cut motherplant, which will kill the suckers.

• Ensure that the cut suckers will not regrow.
• Treat surrounding healthy plants (including weeds) with herbicide.
• No bananas or any alternative host such as Heliconia are grown in the area.
• Fallow the area or plant with wilt-suppressive crops such as maize for a period of 6 to 12 months.
• Burn rice hull to reduce the necessary fallow period:
• 1. Put rice hull on top of the infected field at 1,500 kg/case and burn.
• 2. Three to four weeks later, burn another 750 kg/case and do a third burning of 750 kg/case for another 3 to 4 weeks later.
• 3. The area will be ready for planting 3 to 4 months after the first burning.

2. Cultural Control

• The spread of Moko can be prevented through good drainage conditions and disinfection of used tools and shoes of workers (10% formaldehyde for 10s, or 5% formaldehyde for 30s).
• Bugtok infection can be prevented by removing the male buds by hand at an early stage and bagging the inflorescence with polyethylene, muslin cloth or fine nylon mesh.
• Debelling or debudding: This is the removal of the bell or male bud about 10 cm below the last hand soon after it is set. This procedure helps to increase the size of the lower hands and bunch weight and reduces bird activity and damage. More importantly, this is an effective control measure to prevent infection by insects with the bacteria that causes Moko or bacterial wilt.

1. Cut off the male bud by a knife or machete.
2. Disinfect cutting tools in a formaldehyde solution (10% solution for 10s or 5% solution for 30s) or a 5% sodiumhypochlorite solution  to prevent spread of diseases or to avoid this problem, break the peduncle by hand or use a forked stick.
3. Remove small fingers or false hands to increase finger length, reduce time between shooting and harvesting as well as increase percentage of first class fruit.
4. Leave one finger in the last removed hand to prevent bunch stalk drying and withering back.