Banana Rust Thrips

Chaetanaphothrips signipennis

Banana rust thrips are a widespread problem in the coastal areas of Queensland and northern New South Wales. Predominantly affecting bananas, they have also been found in citrus and some native plants. In bananas they cause superficial damage to the skin which can result in the fruit being downgraded or rejected at market. Banana rust thrips are notably troublesome in areas with red soil and where bunch bagging is not used. Fruit that grows in the early warmer months tends to be more at risk.

Refer to the links below on different thrips species.

Description

Adult thrips are creamy yellow to golden brown, with a slender body up to 1.5 mm long, and wings possessing two dark eye-like patches which are characteristic of adult rust thrips. These patches are often used to distinguish them between smaller male banana flower thrips.

Banana rust thrips can be found at the base of the leaf sheath as it wraps around the stem or in the bunch where fingers come into contact with each other. Early damage appears as water-soaked smoky areas on the fruit where the colonies of both adults and nymphs congregate to feed. These spots progress into the typical rusty red to dark brown discolouration on the fruit. Serious damage can result in longitudinal cracks forming on fruit skin.

NOTE: Rust thrips can sometimes be mistaken for maturity bronzing which also produces a rusty reddish colour on the fruit. This is usually noticeable on the outside of the fruit where fingers are not touching.

Control

Controlling volunteer banana plants, acquiring thrips-free plant material and where possible hot water treatment prior to planting, is recommended to reduce the risk of infestations.

If applied early, bunch covers (which cover the full length of the bunch) can provide some protection, however under heavy infestations these alone will not provide reliable control. Application of a registered bunch dust at the time of fitting bunch covers provides better protection. Fruit should be checked regularly under the covers to assess for any damage.
Monitoring plants is essential for early detection, this is best done by examining five immature bunches per hectare for rust thrips every fortnight. Heavy infestations can result in v-shaped rust markings on the pseudostem, in these cases it’s important to verify the presence of thrips by inspecting the site where the leaf petiole meets the stem with a 10x hand lens.

Once detected, treatment should be applied immediately. For best results chemical control should be used to target the soil dwelling pupal stage in addition to the adults and larvae present on the fruit and plant. Unless both are controlled, reinfestation is very likely, especially during hot and humid conditions.

Often treatments applied to the soil to control banana weevil borer can provide some temporary control of rust thrips. In addition to this, pesticide injection methods used to control scab moth will also provide some early protection.

Movento® Energy and Confidor® Guard are both registered for the control of banana rust thrips in Cavendish bananas. They can only be applied by stem injection into a follower no taller than 1.5 m.

Related Pests

Thrips

Chaetanaphothrips signipennis (Banana rust thrips), Thrips imaginis (Plague thrips), Thrips tabaci (Onion thrips), Thrips safrus (Northern plague thrips), Frankliniella occidentalis (Western flower thrips), Frankliniella schultzei (Tomato thrips), Pezothrips kellyanus (Kelly’s citrus thrips)

While over 6000 species of thrips exist worldwide, only ten per cent are deemed to have an economic impact on crops. The most common group is Terebrantia, which includes many of the damaging species such as onion thrips, western flower thrips and plague thrips. Hosts include citrus, green beans, cotton, mungbeans, cereals, some vegetables, summer pulses, sunflowers, canola and peanuts. Thrips can be vectors for tobacco streak virus and tomato spotted wilt virus.

Refer to links below for a more detailed description on different thrips species.

Plague thrips imaginis

Thrips imaginis

Plague thrips are native to Australia and are widespread across the southern mainland and Tasmania. Their main hosts are pome and stone fruit and will also feed on strawberries, legumes, tomatoes, Eucalyptus spp., grapes, ornamentals, grasses, weeds and a variety of native plants. They are frequently present in citrus trees but do not cause economic damage.

Refer to the links below on different thrips species.

Onion thrips

Thrips tabaci

Onion thrips infest a wide range of hosts, including onions, garlic, leek, beans, cabbage, cauliflower, broccoli, cotton, celery, tobacco, tomatoes, cucumber, strawberries, potatoes and a range of ornamentals. Onion thrips are known vectors of tomato spotted wilted virus (TSWV) and iris yellow spot virus (IYSV) which is a potentially destructive virus of onions.

Refer to the links below on different thrips species.

Northern Plague Thrips

Western flower thrips

Frankliniella occidentalis

A more serious pest than other thrips species because it plays a major role in infecting tomato, potato, capsicum and lettuce crops with the tomato spotted wilt virus (TSWV).

Tomato Thrips

Frankliniella schultzei

Tomato thrips originate from South America and are widespread throughout Australia. They prefer to feed on flowers and have a wide range of hosts including tomatoes, tobacco, capsicums, lettuces, potatoes, grain legumes and several weed species. They are known vectors for tomato spotted wilt virus (TSWV) which can cause considerable yield losses in tomato, capsicum, potato and lettuce crops.

Kellys citrus thrips

Pezothrips kellyanus

Kelly’s citrus thrips (KCT) are a serious pest of citrus in inland Australia, where in the Riverland-Sunraysia region of South Australia alone, it is estimated to cost industry $10 million per annum in crop losses and control measures. KCT feed on the fruit, causing scurfing (or halo) damage at the stem end and rind blemish which results in quality downgrades and reduced pack-out rates. The most affected varieties are Navel and Valencia oranges, lemons and grapefruit.

Refer to the links below on different thrips species.

References

Department of Agriculture and Fisheries, Queensland (2017), ‘Banana Rust Thrips’, https://www.daf.qld.gov.au/business-priorities/agriculture/plants/fruit-vegetable/insect-pests/banana-rust-thrips