Problem Solver – Page 3 – Better Bananas

Stem shatters

Posted on 2018-02-20 by Better Bananas

Stem shatters

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 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).

More info:

2,4-D damage

Cause: Injection of 2,4-D will kill the plant. Overspray or drift from herbicide application may cause lesser symptoms.

Solution: Be extremely careful with chemical applications.

Tissue-cultured off-type

Cause: A genetic abnormality that occurs in tissue-cultured plants.

Solution: Remove affected plants and set additional following suckers on nearby plants.

Banana streak virus

Cause: The banana streak virus (BSV). Symptom expression is sporadic. Symptoms of cucumber mosaic are similar.

Solution: Do not take planting material from infected plants. Eradicate infected plants where symptoms are observed. Confirm diagnosis by looking for yellow black streaks or flashes on leaves or by laboratory tests.

Frost

Cause: Frost during the growing season.

Solution: No cure for damaged plants. Slightly damaged plants may grow out of it.

Small and stunted plants

Posted on 2018-02-19 by Better Bananas

Small and stunted plants

Tissue-cultured off-type

Cause: A genetic abnormality occurring in tissue-cultured plants.

Solution: Remove affected plants and set additional following suckers on nearby plants.

Burrowing nematode

Cause: Severe root damage caused by burrowing nematode affects the plant’s ability to take up water and nutrients from the soil.

Solution: Check a random sample of roots from the whole field to determine if nematodes are the problem and if a nematicide treatment is necessary.

Banana weevil borer

Cause: Tunnelling by larvae of Cosmopolites sordidus in the corm. Sever infestation reduces plant vigour.

Solution: Use stem baits (traps) to establish the severity of the infestation. If numbers exceed an average of 4 weevils per trap, treat with appropriate insecticide. Pheromone traps are also available.

Banana bunchy top

Biosecurity Alert!

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.

Reporting: Under state legislation, banana bunchy top disease must be reported. If you have seen plants with banana bunchy top symptoms within the Southern Queensland banana biosecurity zone, or the NSW Banana Bunchy Top Virus Control Zone contact the Banana Bunchy Top Hotline on 1800 068 371.

If you have seen banana bunchy top outside of these areas, you must report it within 24 hours to the Biosecurity authority in your state (Biosecurity Queensland on 13 25 23, or NSW DPI Biosecurity Hotline 1800 680 244) or the Exotic Plant Pest Hotline on 1800 084 881.

More Information:

Not enough water/dry conditions

Cause: Insufficient water for plant growth.

Solution: Use water scheduling techniques to supply sufficient water to meet the plant’s requirements.

Plants turn yellow and die

Posted on 2018-02-19 by Better Bananas

Plants turn yellow and die

Bacterial corm rot

Cause: The bacteria Pectobacterium spp. (formerly known as Erwinia spp.) that are common soil inhabitants. Plants that are stressed during the dry season can succumb to invasion during the wet season.

Solution: No chemical treatments are available. Ensure adequate moisture levels are maintained during the dry season and provide good drainage during prolonged wet seasons.

Water-logging

Cause: Not enough oxygen for the roots caused by too much water in the soil from rainfall or irrigation.

Solution: Avoid planting in areas that are often water-logged and in heavy soils. Install and maintain the drainage system for your plantation.

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. The fungus 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. There are several “races” of the disease which affect different varieties.

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).

More info:

Herbicide damage (glyphosate)

Cause: Glyphosate spray drift onto green parts of the plant. The first symptom is yellowing of leaves.

Solution: No cure for damaged plants. Be extremely careful when using glyphosate.

Plants kink, bend or fall over

Posted on 2018-02-15 by Better Bananas

Plants kink, bend or fall over

Borrowing nematode (plants fall over)

Cause: Burrowing nematode feeding on roots weakens the plant’s root system.

Solution: Check roots over the whole field to determine if nematodes are the problem and if a nematicide treatment is necessary. Propping or tying string between plants may prevent some losses.

Banana weevil borer (plants fall over)

Cause: Tunnelling by larvae of Cosmopolites sordidus in the corm. Sever infestation reduces plant vigour.

Solution: Use stem baits (traps) to establish the severity of the infestation. If numbers exceed an average of four weevils per trap, treat with appropriate insecticide. Pheromone traps are also available.

More info:

Banana weevil borer – general information

Poor tying (plants bend or kink)

Cause: Incorrect bunch and tree support.

Solution: Ensure tying or propping is done correctly.

Heat stress/lack of water (plants bend or kink)

Cause: Extreme heat and or dry conditions.

Solution: Use water scheduling techniques to supply sufficient water to meet the plants’ requirements.

Fruit rotting after harvest

Posted on 2018-02-15 by Better Bananas

Fruit rotting after harvest

Anthracnose

Cause: The fungus Colletotrichum musae. Spores are produced on dead banana material and are spread to young fruit in water droplets. The fungus remains dormant in the tissue until the onset of ripening.

Solution: Handle harvested banana fruit with care to avoid damage. Apply appropriate post-harvest fungicide treatment.

Crown rot

Cause: Several organisms can be responsible for causing crown rot symptoms. These include Musicillium theobromae, Fusarium equiseti-incarnatum (species complex), Colletotrichum musae and Thielaviopsis musarum. Symptoms can vary from fungal growth ‘fluff’ present on the cut crown surface through to complete breakdown of fruit.

Solution: Application of appropriate post-harvest fungicides will assist in minimising symptoms in the supply chain.

More info:

Crown end rot research

Fruit rotting in field

Posted on 2018-02-15 by Better Bananas

Fruit rotting in field

Sunburn

Cause: Insufficient bunch shading during prolonged high temperatures.

Solution: There is no cure for affected fruit. Maintain good canopy cover and ensure bunch covers are applied properly. It may be necessary to pull a leaf down over the bunch for protection.

Cigar end

Cause: The fungus Musicillium theobromae (formerly known as Verticillium theobromae). It enters the fruit from the dead floral parts and extends 10 to 20 mm into the fruit.

Solution: Cigar end is a minor disease and specific control measures are not warranted.

Mixed ripe

Cause: Various stresses (severe leaf spot, pest damage, water and nutrition) reduce the rate of fruit filling.

Solution: Improve crop management to limit stresses on the plant.

Punctures or splits on fruit

Posted on 2018-02-15 by Better Bananas

Punctures or splits on fruit

Birds or bats

Cause: Birds and bats landing on the bunch to feed on nectar from immature flowers.

Solution: Cover bunches promptly and use thick covers. For Lady Finger apply covers before any bracts lift on the bunch.

Bell injection

Cause: Incorrect bell injection technique.

Solution: Train staff to inject slightly above one-third from the top of the bell.

Diamond spot

Cause: The fungus Cercospora hayi. Spores are produced on dead banana material.

Solution: Diamond spot is a minor disease especially where control of leaf spot is effective.

Rust or bronzing on fruit

Posted on 2018-02-15 by Better Bananas

Rust or bronzing on fruit

Banana rust thrips

Cause: Feeding by Chaetanaphothrips signipennis from bract fall to harvest causes a rust brown skin discoloration. This symptom should not be mistaken for maturity bronzing, which is more prevalent on the outer exposed areas of the fingers.

Solution: Soil treatments for banana weevil borer will help control the soil thrips population. Treat bunches at the time of bunch covering.

More info:

Banana rust thrips — general information and monitoring and control options
More images

Maturity bronzing

Cause: Oxidation of cell contents, possibly from a water and nutritional imbalance, causes the epidermal cells to discolour, lift and break.

Solution: In the short term, bunches should be harvested early before symptoms become more severe. Avoid water and nutrient stresses in the plant.

More info:

Maturity bronzing—stretching the limits on fruit quality

Spray burn

Cause: Incorrect chemical application rates, problems with compatibility or environmental conditions.

Solution: Check that you are using registered chemicals and are applying them at the correct rates. Make sure that your spray application equipment is cleaned regularly.

Silvering thrips

Cause: Feeding by Hercinothrips bicinctus.

Solution: This is a minor and rare pest of bananas grown in north Queensland. No specific treatments are required.

Mites

Cause: Banana (strawberry) spider mite, Tetranychus lambi, feeding on the fingers. More severe infestation will result in the damage spreading over the entire fingers.
Two-spotted mites, Tetranychus urticae, feed primarily on the tips of fingers, causing silver-grey superficial damage. Webbing forms ‘bridges’ between heavily infested fingers.

Solution: Severe mite outbreaks are usually the result of poor insecticide management, especially foliar application of disruptive pesticides that destroy beneficial species such as the Stethorus spp. beetle. Treatments with a suitable miticide may be required during periods of hot, dry weather when mite build-up can be rapid.

More info:

Spots of fruit

Posted on 2018-02-14 by Better Bananas

Spots on fruit

Banana spotting bug

Cause: Feeding (sucking) by banana spotting bug, Amblypelta lutescens lutescens, usually on the exposed outer curve of the fingers.

Solution: Damage is more severe on blocks adjacent to rainforest. No specific treatments required. If more than 5% of bunches are affected, spot spray.

Fruit speckle

Cause: Caused by multiple species of fungi including Colletotrichum musae, Fusarium oxysporum and Fusarium semitectum. Spores are produced in large numbers on dead leaf material during wet conditions and are spread in air currents to the fruit.

Solution: Fruit speckle is generally a minor disease that can become problematic in seasonally unfavourable weather conditions. Under normal conditions, a fungicide leaf spot spray program should assist and keep levels low.

More info:

A guide to identifying fungal fruit diseases

Fruit flies

Cause: Banana fruit fly, Bactrocera musae, and Queensland fruit fly, Bactrocera tryoni, laying eggs (stinging) in the pulp of banana just below the skin. The banana fruit fly can sting green fruit but the Queensland fruit fly only stings ripening or yellow fruit.

Solution: Chemical control should not be required since fruit is harvested at the hard green stage before either of the fruit flies can complete their life cycles. Do not leave over ripe fruit in the field. If mixed ripe fruit causes hot spots in the plantation, spot spray with an appropriate chemical.

Flower thrips

Cause: Scarring from egg-laying by flower thrips, Thrips hawaiiensis on young fruit when still covered by the bracts.

Solution: Insecticide injection at bell emergence for control of scab moth also controls flower thrips.

More info:
Banana flower thrips – general information

Spray burn

Cause: Spraying with excessive volumes of chemical or inappropriate chemical use.

Solution: Use only registered chemicals and apply according to the label directions.

Sooty blotch

Cause: Multiple fungal organisms are associated with the symptoms.

Solution: Lady Finger and Ducasse are more prone to sooty blotch than Cavendish-type bananas. A post-harvest dip of sodium hypochlorite at 100 ppm for 5 minutes followed by immediate rinsing, is highly effective in removing sooty blotch.

More info:

A guide to identifying fungal fruit diseases

Sooty mould

Cause: Sooty mould fungi that develop on the honeydew secretions of the banana aphid, Pentalonia nigronervosa.

Solution: Natural control by parasites and predators provides adequate suppression. Infestations are more obvious during cooler weather in autumn and spring. Spot treatment with a suitable pesticide is occasionally required as the mould can be difficult to remove from fruit.

More info:

A guide to identifying fungal fruit diseases

Scabs on fruit

Posted on 2018-02-13 by Better Bananas

Scabs on fruit

Scab moth

Cause: Larvae of Nacoleia octasema feeding on the fruit between the bunch stalk and the hand. Only occurs from bunch emergence to bract fall.

Solution: Newly emerged bells require pesticide injection while they are still upright. When the plants are growing quickly during summer, treat blocks at least weekly.

More info:

Banana scab moth – summary

Sugarcane bud moth

Cause: Small grey larvae of Opogona glycyphaga. They feed and pupate mainly towards the tips of the fingers and where the flower end of a lower finger meets a finger in the hand above.

Solution: This pest lays its eggs on fruit after all the bracts have fallen. Treat bunches with insecticide during bunch covering.

Banana fruit caterpillar

Cause: Larvae of Tiracola plagiata feeding on leaves and fruit. Damage is usually confined to a few bunches and feeding on fruit is confined to the outside of fingers.

Solution: Although attack to a single bunch can be very severe, only a few bunches are damaged and specific treatments are not usually needed. Standard treatments for rust thrips and sugarcane bud moth help to control fruit caterpillar. If damage is noted on more than 5% of bunches, treat with a pesticide.

Corky scab

Cause: Scarring from feeding and egg-laying by flower thrips, Thrips hawaiiensis on young fruit when still covered by the bracts.

Solution: Insecticide injection at bell emergence for control of scab moth also controls flower thrips.

More info:

Banana flower thrips – Summary

Rub

Cause: Rubbing between the bag and young fingers due to prolonged strong winds. Leaves rubbing against the fruit cause similar symptoms.

Solution: Retaining existing vegetation or planting specific windbreak trees can reduce the damage caused by strong winds.