Yellow leaves

Bunchy top

Cause: The banana bunchy 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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Yellowing appears first on the older leaves but all leaves quickly become affected.

Nitrogen deficiency

Cause: Insufficient nitrogen available for the plant due to inadequate fertiliser applications or leaching and gaseous loss of the nitrogen fertiliser applied.
Solution: Appropriate application of nitrogen fertiliser. You need to know your soil type, climate, past fertiliser program, and soil and leaf analysis results when determining the fertiliser rate.
Yellowing starts in the oldest leaves.

Potassium deficiency

Cause: Reduced availability of potassium for plant uptake. Enhanced by leaching losses of potassium and/or inappropriate fertilisation.
Solution: Appropriate application of potassium fertiliser. Knowledge of your soil type, climate, past fertiliser program, and soil and leaf analyses need to be considered in determining fertiliser rate.
Leaf margins of the older leaves remain green and the area between the leaf margin and the midrib yellows.

Magnesium deficiency

Cause: Reduced availability of magnesium for plant update. Usually due to inappropriate fertilisation causing an imbalance.
Solution: Appropriate application of magnesium fertiliser. Knowledge of your soil type, climate, past fertiliser program, and soil and leaf analyses all need to be considered in determining fertiliser rate.

Water-logging

Cause: Poor soil aeration which reduces root function and leads to water and nutrient stress.

Solution: Depends on soil type and situation but usually involves surface and subsurface drainage works.

Panama disease (Fusarium wilt)

Biosecurity Alert

Cause: The fungus Fusarium oxysporum f. sp. cubense which is a soil-borne organism. It is spread in water, soil and planting material. It enters the plant through the roots, and blocks the conducting tissue within the plant resulting in wilting, yellowing of leaves, splitting of pseudostem and death of the plant.
Solution: There is no cure for affected plants. Use only approved planting material and do not plant in previously infested areas.
Biosecurity obligation: Panama is a notifiable disease and you must report any suspicious plants. If you suspect Panama disease you must notify Biosecurity Queensland immediately (13 25 23).
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Yellowing of leaves caused by Bacterial corm rot.

Bacterial corm rot

Cause: The bacteria Pectobacterium spp. (formerly known as Erwinia spp.) which are widespread in most soils. Plants that are stressed from heat or lack of water during the dry season can succumb to bacterial invasion during the early part of the wet season.
Solution: There is no cure for infected plants. Avoid stress conditions. Ensure adequate moisture levels are maintained during the dry season.