Spider mites – life cycle and behaviour

Posted on by Better Bananas

Spider mites

Life cycle and behaviour

Both the banana spider mite (Tetranychus lambi) and the two-spotted mite (Tetranychus urticae) are often simply referred to as ‘spider mites’. Both are common pests of a broad range of crops and are widely distributed.

The life cycle and appearance of the banana spider mite and the two-spotted mite are similar. Both mites are typically found on the underside of leaves, only being present on the top side in very high infestations. The main distinguishing feature between the two types of mites is that high populations of the two-spotted mite are always associated with webbing (similar to spiders), while this is absent in infestations of the banana spider mite. Webbing occurs near mite colonies, typically on the underside of the midrib or in severe infestations, down the leaf veins. The two-spotted mite is more commonly found on bananas in South-East Queensland and northern NSW. By comparison, the banana spider mite predominantly is in Far North Queensland and is also identifiable as it is more straw coloured and lacks spots.

The life cycle of the mite (red arrows indicate parts of the plant affected)

The straw-coloured or greenish adult banana spider mites are usually less than 0.5mm in length and are best seen with the aid of a magnified (10X) hand lens. Under good light, the eight-legged adults have a spider-like appearance that can just be made out with the naked eye.

The very small transparent to yellow, spherical eggs are laid singly on the leaf surface and, upon hatching, pass through two nymphal stages before becoming adults. In hot conditions, the life cycle can be as short as seven to ten days.

Adult spider mite with eggs
Adult spider mite and its spherical eggs. Note the dark leaf tissue, an indication of dead leaf cells caused by mite feeding

By comparison, the adult female of the two-spotted mite (T. urticae) lives two to four weeks and can lay several hundred eggs during her life.1 Their quick life cycle and the ability of females to produce many eggs, can mean populations build rapidly if conditions are favourable.

Spider mites mainly use wind and small spun lines of web to migrate. The two-spotted mite is known to travel in winds as low as 8 km/h but prefers stronger winds.2 Mites also have the ability to move by walking on or short distances between plants2. Spider mites can migrate at any time, tending to move on when their populations become high, predators become abundant or the quality of food sources declines.

References

  1. Florida Department of Agriculture and Consumer Services, Division of Plant Industry 2009, University of Florida, viewed 17 January 2022, https://entnemdept.ufl.edu/creatures/orn/twospotted_mite.htm#top
  2. Seeman, O, Beard, J 2005, National Diagnostic Standards for Tetranychus Spider Mites, Plant Health Australia, Canberra

Download this information as a factsheet

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
Email betterbananas@daf.qld.gov.au 

 
This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland 
This information has been prepared as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

A guide to identifying banana fruit fungal issues.

Posted on by Better Bananas

A guide to identifying banana fruit fungal issues.

Bananas are susceptible to various fungal diseases that can affect their fruit quality. Correctly identifying these fungal issues in banana fruit is crucial to understanding how to manage and prevent further damage. This guide explores some of the most common fungal problems that affect banana fruit.

If your issue isn’t listed here or you are having problems identifying what is causing damage to your crop check out the Better Banana’s problem solver section here. 

Sooty blotch
Sooty blotch
Sooty blotch water-soaked shadowing
Sooty blotch
Sooty blotch damage in ripe fruit
Sooty blotch damage in ripe fruit

Sooty blotch

  • Multiple fungal organisms are associated with the symptoms.
  • Presents as water-soaked shadowing.
  • Damages skin surface and can’t be removed by rubbing.
Sooty mould
Sooty mould powdery growth
Sooty mould - when zoomed it is possible to see insect casts (aphids)

Sooty mould

  • Caused by the combination of sap-feeding insects (banana aphids and mealybugs) and fungi, namely the genus Cladosporium.
  • The fungus grows on the honeydew secreted by aphids or mealybugs and the fungal infection is secondary.
  • Black powdery growth occurs in dark layered sheets which can be peeled away or removed by rubbing (but the stain remains).
Fruit speckle
Fruit speckle - smooth reddish brown to black spots (0.5-1 mm) with water-soaked margins.
Fruit speckle
Fruit speckle - heavy cases can see speckle coalesce
Fruit speckle affecting all fingers in cluster
Severe fruit speckle damage

Fruit speckle

  • Caused by multiple species of fungi including Colletotrichum musae, Fusarium oxysporum and Fusarium semitectum.
  • Occurs first on fruit neck.
  • Smooth reddish brown to black spots (0.5-1mm) with water-soaked margins.
  • Previously known as ‘swamp spot’, ‘salt and pepper spot’ and ‘Deightoniella spot’.
Deightoniella torulosa
Deightoniella torulosa.
Deightoniella torulosa
Spots are typically larger than fruit speckle (2-4mm) and sunken on green fruit.

Deightoniella spot

  • Caused by Deightoniella torulosa
  • Spots are typically larger than fruit speckle (2-4mm) and sunken on green fruit.
  • Less commonly detected in FNQ.

Download this information as a factsheet.

This information has been developed as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Banana weevil borer – monitoring

Posted on by Better Bananas

Banana weevil borer Cosmopolites sordidus

Monitoring

Adult banana weevil borer activity increases during warm and/or wet weather and decreases during cold and/or dry conditions. Periods of greatest adult activity are in spring (September-October) and autumn (March-April). If blocks are suspected of infestation, trapping should concentrate on these times to determine whether chemical treatments are needed or not. In addition, it is advisable to set traps prior to a new planting or during the fallow period. This is to ensure that any banana plant material has decomposed entirely, eliminating the possibility of any remaining adult banana weevil borers being present in residues that might affect the new crop.

If infestations are suspected adult banana weevil borer monitoring should be carried out every month, except during the colder months when the time frame can be extended to six weeks. Banana weevil borer numbers at baits placed during adverse conditions may not accurately reflect actual adult population levels, as it has been shown that only 5-15% of the actual population will appear on baits under these conditions.

There are a few main methods of monitoring banana weevil borers, which are outlined below:

Bait trapping

Adult banana weevil borer numbers can be monitored by baiting (trapping). Baits are made by cutting a fresh pseudostem into slices about 10cm thick . The pseudostem material selected for making baits should ideally be taken from the lower portion of the stem of freshly harvested plants. One bait is placed close to the base of each plant, with one cut surface in full contact with the ground, and covered with leaves to prevent the bait from drying out. Twenty or more baits should be used in known hot spots to obtain a good indication of banana weevil borer numbers. The ground directly beneath the bait should be cleared of any weeds or plant material that can shelter adult banana weevil borers and hinder rapid checking of the baits. After three to four days, the baits are turned over and the adult banana weevil borers are counted (Hint! Look for banana weevil borers on the ground where the bait was resting as well as the base of the bait in contact with the ground).

Adult banana weevil borer numbers are recorded from each bait and, knowing the total number of baits set and banana weevil borers counted, the average number of adults per bait can be calculated by dividing the total number of banana weevil borers by the number of baits set.

Banana weevil borer BWB bait trapping
Banana pseudostem placed near the base of a banana plant to trap banana weevil borer.
Banana weevil borer BWB bait trapping
Banana pseudostem covered with a leaf to prevent drying out.
Traditional pitfall trap that is used with pheromones. Here the lid has been removed to count the number of banana weevil borer’s present.

Pheromone trapping

Another option for monitoring is the use of pheromone-baited traps, which contain a substance (sordidin) that specifically attracts adult banana weevil borers. These baits attract both male and female banana weevil borers and can attract individuals up to 20m away from the trap, however, this efficiency is reduced by rainfall. Baits need to be replaced every 30 days, as lures run out (depending on lure concentration – read labels for specifics). Different types of traps are commercially available for growers.

Corn damage assessment

Larval damage can be assessed by rating the percentage of tunnelling in the corm of harvested plants.

The larger the area affected the higher the pressure of banana weevil borers. This monitoring is destructive and requires the cutting of plants, and is more encouraged as a monitoring tool to see how known infestations are responding to treatment, rather than a diagnosis of infestations.

Download this information as a factsheet

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
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Banana weevil borer – general information

Posted on by Better Bananas

Banana weevil borer Cosmopolites sordidus

General information 

Description and life cycle

The eggs of the banana weevil borer can be found in a pit that has been chewed into the side of the pseudostem. The site of egg laying is nearly impossible to find due to banana sap congealing and covering the hole. The larvae continuously feed within the corm producing distinctive tunnels until they are almost 2cm long when they move towards the outer edge to pupate.

The lifecycle of banana weevil borers (particularly egg and larval periods) is extremely temperature dependent and is shorter in warmer conditions. The total time from egg hatching to adult emergence can be as short as 12 weeks in ideal conditions in northern Queensland.

Banana weevil borer lifecycle
Lifecycle of the banana weevil borer (arrow indicating part of plant affected).
banana weevil borer egg
Banana weevil borer egg in banana tissue, egg circled in red.

Newly emerged adults are reddish brown but quickly assume their characteristic shiny black appearance as their exoskeleton hardens. The adults are sluggish and fake death if disturbed. However, it can be determined whether they are indeed alive, by gently blowing on them as live adults will wiggle their legs and snouts.

Banana weevil borers have functional wings, however, they rarely, if ever, fly. Instead, they can travel by walking up to 6-7 metres between plants at night, resulting in a very slow spread. Movement is reduced during dry weather, as adults remain in the corm to avoid desiccation. Dispersal of banana weevil borers over larger distances is primarily by the introduction of infested suckers and bits at planting.

Banana weevil borer
An adult banana weevil borer with scale.

Occurrence & seasonality

Banana weevil borer is found in all major banana growing areas throughout the world. Bananas and other species of the genus Musa are the only known hosts. First recorded at Mackay in 1896, the banana weevil borer has since spread to all major banana growing areas in Australia.

It has been observed that there are two distinct peaks in the emergence and activity of adults– the first in spring during September and October, and the second in autumn, during March and April. These peaks are particularly evident in subtropical regions where activity almost ceases during winter. In the Far North Queensland tropics, where winter temperatures are not as low, activity continues throughout the year although at a reduced rate in winter. In Far North Queensland, dry conditions greatly reduce adult activity, as adults remain in the corm to avoid desiccation, whereas rainfall may be a major factor in increasing adult activity.

 

Damage 

Most of the damage is done by the tunnelling of the larvae which occurs exclusively within the corm. Evidence of larval tunnelling is not noticeable since all the tunnelling is confined to the corm below the surface. In heavy infestations, tunnelling will extend for a short distance up the pseudostem; the presence of tunnels can be seen if the pseudostem is cut close to the soil surface. In plants that have fallen out or snapped off the pseudostem may decay more slowly and tunnelling may extend a greater distance up the pseudostem.

Newly planted blocks are more vulnerable to infestations of banana weevil borer as they don’t yet have a substantial corm (especially tissue-cultured plants), meaning tunnelling will cause proportionally more damage.

BWB larvae
Banana weevil borer larval stage (in red) on banana roots

Tunnelling in young plants can cause the death of the cigar leaf if banana weevil borers damage the primary meristem, which is especially likely if tunnelling has extended into the lower pseudostem. However, healthy, fast-growing plants can withstand considerable infestation without showing obvious signs of reduced vigour. 

Typical symptoms of a severe infestation are reduced plant growth, choking, yellow leaves and weak or dying suckers. Environmental stress has been shown to exacerbate the symptoms of banana weevil borer infestations. Plants under attack are also prone to falling out (particularly in windy weather) but the root system of fallouts must be inspected carefully to ascertain the cause. Fallouts can occur from both banana weevil borer and burrowing nematode damage. When banana weevil borer is the cause there is an obvious breakage with the lower part of the rhizome and roots are often retained in the ground (snapped off). Whereas if burrowing nematode is the cause the entire corm is exposed along with stubby roots (‘roll-out’).

Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.
Dark tunnelling pattern from banana weevil borer shown throughout corm cut close to the soil surface.

Note: Banana weevil borers will be at higher pressure after weather events that cause serious plant damage, or in blocks that use cultural practices that encourage damage or breakages, such as desuckering, as they are attracted to fresh exposed plant volatiles.

Download this information as a fact sheet

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana weevil borer – management

Posted on by Better Bananas

Banana weevil borer Cosmopolites sordidus

Management

Cultural

The use of clean (banana weevil borer-free) planting material and maintenance of trash and weed-free areas near plants are two important factors in reducing the impact of this pest in bananas. Ideally, planting material should be obtained from an accredited QBAN nursery. If you are unable to use tissue culture the next best option is to use planting material from your own farm that is sourced from a block that is clean from pest and disease.

When planting into old banana land, allow at least six months of fallow after all old banana material has rotted down. This will help to prevent a carryover of weevil borer adults. Cut up all fallen and harvested pseudostems to prevent banana weevil borer breeding. This is particularly important in subtropical regions where drier, cooler conditions result in slow breakdown of plant material. Glyphosate injection for crop removal is encouraged to ensure adequate plant destruction to reduce weevil population levels.

Tissue culture plants
Banana planting material from clean sources, such as accredited plant nurseries, ensures that no banana weevil borers are present.
beauveria bassiana infected banana weevil borer adult BWB
Dead adult banana weevil borer infected with the fungus Beauveria bassiana.

Biological

A large range of general predators including flatworms, ants, beetles and cane toads assist in reducing banana weevil borer numbers. Research is being undertaken to determine the effectiveness of insect parasitic nematodes, which could prove suitable as biological control agents for banana weevil borer control.

Some international research, and research in NSW have shown some success using laboratory assays of entomopathogenic nematodes, Steinernema spp. and Heterorhabditis spp. However, to date, Queensland-based research has been unable to replicate positive results in the field, instead showing no difference between treated plants and untreated (control) plants, indicating that more in-field research is still needed.

Initial research in Australia shows that some insect diseases (entomopathogens) such as the fungus, Beauveria bassiana, have the capacity to reduce banana weevil borer populations, but more research is still needed.

Chemical

If the average banana weevil borer counts from bait trapping are more than two per trap (subtropics) or more than four per trap (tropics), registered chemical treatments should be applied according to label directions. If average counts are less than these, treatment is not considered necessary. Pheromone trapping doesn’t currently have a threshold value.

When choosing a chemical, it is essential to consider the life stage and behaviour of the banana weevil borer. The adults typically move around corms during spring and autumn to feed and lay eggs. To achieve optimal control, it is recommended to apply chemicals during these peak activity periods, using banded or butt spray applications that apply insecticides adjacent and/or onto the plants . By comparison, injection treatments aim to control larvae within the corm and therefore may have more flexibility in when they can be applied. However, some of these chemicals should not be applied during the dry season, as these chemicals have shown an increased incidence of mite flares. Always check the product label for guidance.

Chemical options are generally older chemistries that are disruptive to integrated pest management and/or other insects present throughout blocks. When trying to control banana weevil borer, certain chemicals have been known to cause mite flares. Therefore, it is crucial to only use spray treatments when the infestation has reached critical levels. Insecticide resistance is a threat with current options available, so chemical choices and modes of action should be rotated to reduce the risk of resistance. Always check the APVMA website for current chemical registrations before use. All chemical applications should be made according to the directions on the label. Resistance management plans should be followed to reduce insecticide resistance risk, see CropLife plans here.

Banana weevil borer BWB chemical options

Download this information as a factsheet

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
07 4220 4177 or email betterbananas@daf.qld.gov.au 

 
This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana weevil borer Cosmopolites sordidus

Posted on by Better Bananas

Banana weevil borer

Banana weevil borer is found in all major banana growing areas throughout the world. Bananas and other species of the genus Musa are the only known hosts.

Often infestations of banana weevil borer will go unnoticed until the plant falls out, as most of the damage is done by the tunnelling of the larvae within the corm. In heavy infestations, tunnelling will extend for a short distance up the pseudostem, the presence of tunnels can be seen if the pseudostem is cut close to the soil surface. Other typical symptoms include reduced plant growth, choking, yellowing leaves, and weak or dying suckers. If infestations are detected, monitoring is essential to determine the levels present and appropriate management actions. 

Planting with clean material is essential to prevent banana weevil infestations. Plants from an accredited nursery are optimal, or the next best option is using clean planting material from your own farm.

Banana weevil borer
An adult banana weevil borer with scale.
Always use clean planting material to reduce the risk of a banana weevil borer infestation.

More information

For a general description for identification and detailed life cycle, seasonality and the damage that banana weevil borers can inflict on bananas click here. 

Monitoring should occur in peak times to determine whether chemical treatments are needed or not. To learn more about types of traps that are available for monitoring click here.

For information on how to manage banana weevil borer infestations and how to avoid infestations to begin with click here.

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland and Treverrow, N., Pearley D., and Ireland, G 1992 Banana weevil borer : a pest management handbook for banana growers. : NSW Agriculture, North Coast Region; NSW Banana Industry Committee; Horticultural Research & Development Corporation.
This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.
Hort innovation logo

Banana flower thrips

Posted on by Better Bananas

Flower thrips

Banana flower thrips (Thrips hawaiiensis) are a tiny pest frequently present in banana bunches. For most growers in Far North Queensland flower thrips are not the main bunch pest which leads to economic losses. However, large enough infestations can cause damage to fruit that does not meet market specifications. Damage caused by flower thrips is more significant in warm dry conditions with lower relative humidity, such as South East Queensland and northern New South Wales.

female Flower thrips to scale
Adult female flower thrips measure 1mm in length

Correct and timely bell injection is critical for the control of flower thrips. It must be performed when the bell is upright to ensure the insecticide solution provides protection to the entire bunch. Flower thrips are from the same family as Banana rust thrips (Chaetanaphothrips signipennis). Unlike banana rust thrips, flower thrips spend their entire life cycle on the banana plant, therefore, soil treatment does not provide control of flower thrips. 
 

Flower thrips cause damage to the peel of banana fruit from feeding and ovipositing (egg laying). These ovipositions resemble minute raised pimples on the young immature skin. These are readily seen because of a dark raised centre and can be confirmed by lightly touching the raised area with your fingertip. These oviposition marks almost disappear as the fruit matures. However, extensive damage from feeding from adult flower thrips can cause superficial scarring known as ‘corky scab’. This damage is usually confined to the lower hands (as flower thrips damage increases on lower hands as populations increase as they move down the bunch if it hasn’t been treated). Usually it is first noticeable on the outer whirl,  where the neck meets the cushion, but can extend to the outer curve of the fruit.  

Close up of flower thrips damageovipositions (pimples) on young banana fruit.
Severe flower thrips damage causing corky scab damage.

More information

This information has been prepared as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Banana flower thrips – general information and management

Posted on by Better Bananas

Banana flower thrips Thrips hawaiiensis

General information and management

Occurrence and seasonality

Banana flower thrips are common in banana flowers and among the fingers of newly emerged hands. This pest is found anywhere bananas are grown but its damage is more significant in the less humid, warm and dry climate of South East Queensland and northern New South Wales. Flower thrips are active throughout the year, with increased activity in January through to April. However, as long as flowers are present they can continuously breed.

Adult female flower thrips measure 1mm in length

Description and life cycle

Female flower thrips cause the most damage. They are 1mm long with a pale brown head and thorax and have a black abdomen. They are generally found sheltering under the bracts or inside the flowers. Male flower thrips are smaller (about 0.7mm long), uniformly cream coloured and tend to occur on the outer surface of the bracts.

Adults and nymphs are found on newly emerged bunches and invade the fruit early when the bunch is still covered by its bracts. Recent work has found that flower thrips are present very early in bunch development, inside the bell whilst it is still upright. Flower thrips breed all year round if flowers are present and migrate progressively down the bunch as bracts lift.  The lifecycle takes about three weeks in summer, with full development from the egg to the adult taking place on the bunch or in other parts of the plant.

Damage

Damage to fruit is the result of superficial scarring caused by feeding and ovipositing (egg laying). Oviposition damage resembles minute raised pimples on the young immature fruit skin. These have a dark raised centre and can be confirmed by lightly touching the raised area with the fingertips.

Extensive feeding damage causes a ‘corky scab’, a slightly raised grey corky skin covering. This damage is usually confined to the lower hands (flower thrips damage increases on lower hands as populations increase as they move down the bunch, if it is untreated). Usually, it is first noticeable on the outer whirl, where the neck meets the cushion, but can extend to the outer curve of the fruit. 

Close up of flower thrips damageovipositions (pimples) on young banana fruit.
Severe flower thrips damage causing corky scab damage.

Monitoring

If flower thrips damage is being picked up in the packing shed, the best solution would be to speak to your bell injectors, revise training and ensure that bell injections are being performed correctly (right time and right position).

Flower thrips damage is easy to find in the shed, but it is also possible to find it out in the field. Monitoring for early detection of flower thrips can be done by examining bells of bunched plants every time you’re in the paddock. When large numbers of flower thrips are present, they cause bract-feeding patterns which are ‘lace-like’ in appearance and are lighter than the mauve bracts. These are more pronounced at trimming (when flower thrips populations are highest) and although bunches may already have damage, it gives you an early indication of high pest pressure allowing you to revise training with bell injectors, approximately 12 weeks earlier if assessing damage at harvest in the shed.

zoomed in bract feeding by flower thrips
Flower thrips feeding damage to bract, evident at trimming. Zoomed in for a clearer depiction of ‘lace-like’ feeding pattern.

Control

Chemical

Chemical control is best achieved with correct bell injection. Flower thrips can make their way between the bracts into the bell and damage very young fruit before bell injection. Therefore, to limit the extent of this damage, the timeliness of bell injection is important.  Inject bells whilst still upright. Increase the frequency of bell injecting during warmer months to account for increased plant growth (if possible, as short as every 4-5 days and extending out to every 7 days in winter). Always check the APVMA website for current chemical registrations before use. Below are insecticides currently registered (March 2023) and permitted for bell injection to control flower thrips.

Biological

A range of predatory bugs, predatory mites, ladybird beetles and lacewings can assist in reducing the build-up of flower thrips. Choosing chemical products that are less likely to kill these beneficial insects may assist in suppressing background pest populations.

More information

The Better Bananas team Department of Agriculture and Fisheries South Johnstone 07 4220 4177 or email betterbananas@daf.qld.gov.au

Download this information as fact sheets

This information is adapted from; Pinese,B., Piper, R 1994, Bananas insect and mite management, Department of Primary Industries Queensland

This information has been prepared as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Plants

Posted on by Better Bananas

Plants symptoms and causes

Plants kink, bend or fall over

Click here to view the plants kink, bend or fall over symptoms and causes.

Plants turn yellow and die

Click here to view the plants turn yellow and die symptoms and causes.

Small and stunted plants

Click here to view the small and stunted plants symptoms and causes.

Stem shatters

Click here to view the stem shatters symptoms and causes.

Internal stem discolouration

Click here to view the internal stem discolouration symptoms and causes.

Green leaves dropping

Click here to view the green leaves dropping symptoms and causes.

Leaves bunching at top of plant

Click here to view the leaves bunching at top of plant symptoms and causes.