Abnormal bunches

Abnormal bunches

Stress before bunch emergence (distorted bunches)

Cause: Bunches initiated during extremely hot weather show twisting of the tail of the bunch, which is caused well before the bunch has emerged. Flooding can also lead to abnormal bunch development.

Solution:
If possible, avoid production in flood-prone areas.

2,4-D damage (distorted bunches)

Cause: Spray drift onto the plant from nearby herbicide application.
Solution: Plants may grow out of the problem if they are growing vigorously. Severely affected plants will die, but the following suckers may grow out of the problem. Always be extremely careful with chemical applications.
Note that the dark flower bracts have not fallen off. If left in the bunch they can rot, creating problems with fruit quality.

Tissue-cultured off-type (bracts retained)

Cause: Bract retention is a genetic trait and is usually associated with dwarfness. It is most commonly noticed in dwarf off-types in tissue-cultured plantings.

Solution:
Remove the bracts by hand at bagging. Cull dwarf off-types and set additional following suckers on nearby plants. 
The distorted and misshapen fruit produced is unmarketable and the bunch is prone to sunburn.

Choke throat (poor bunch emergence)

Cause: Stresses (water-logging, cold, water or nutrient shortage, 2,4-D damage, banana streak virus and bunchy top) that limit the normal elongation of the true stem and extrusion of the emerging bunch. Some varieties are tissue-cultured off-types and more sensitive.

Solution: Choose varieties less prone to choke throat and cull tissue-cultured off-types showing these symptoms. Improve management to limit stresses suffered by the plant. Always be extremely careful with chemical applications. 

Wind damage (poor bunch emergence)

Cause: Cyclonic strength winds damaging the pseudostem before the bunch emerges.
Solution: No control is possible. Windbreaks may reduce the severity of wind damage slightly. 
The bunch hasn't emerged because of choking of the leaves. Click on the image for close-up of leaf symptoms.

Bunchy top (poor or no emergence)

Cause: The banana bunch top virus (BBTV) which is spread on infected planting material and by the banana aphid, Pentalonia nigronervosa. BBTV is not present in tropical Australia, and movement of planting material is controlled by legislation.

Solution:
There is no cure for this disease and all infected plants must be eradicated. Outbreaks must be reported to your state primary industry authority.

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