Mangosteen Borer

Symptoms by part

Causes

• Presence of adult moths in the orchard during the fruit development stage.
• Lack of physical barriers to prevent egg laying on the fruit surface.
• Accumulation of fallen, infested fruit on the ground which allows the life cycle to continue.

Could be confused with

• Fruit fly damage · Fruit fly stings are usually much smaller and often cause a soft, sunken spot rather than the distinct tunneling and frass associated with the borer.
• Fungal fruit rot · Fungal infections typically show fuzzy growth or dark lesions on the surface without the presence of entry holes or internal larval tunnels.

Treatment

1. 1. Collect and destroy all fallen fruit from the ground immediately to break the life cycle.
2. 2. Prune away any fruit showing visible entry holes to prevent the larvae from completing their development.
3. 3. Bag individual fruits with paper or mesh sleeves once they reach a small size to prevent moths from laying eggs on the rind.
4. 4. Apply spinosad to the fruit surface during the early stages of development if infestation pressure is high, follow the label.

Without chemicals

• Bagging individual fruits with protective sleeves.
• Sanitation by removing and burying or burning all infested fruit.
• Clearing debris from under the tree canopy to expose larvae to predators.

Chemical options

• Spinosad, apply as a localized spray to the fruit surface, follow the label.

Preventing it

• Maintain a clean orchard floor by removing all dropped fruit.
• Use fruit bagging as a standard practice for every harvest.
• Encourage natural predators like birds and parasitic wasps in the orchard.

When to act

Act as soon as the fruit begins to set and swell. If the infestation is widespread and affecting the majority of your harvest, you may need to consult a local tree surgeon or agricultural specialist for orchard management advice.

Questions people ask

Can I eat fruit that has been attacked by the borer?

It is not recommended, as the tunnels often introduce secondary bacteria and fungi that cause the fruit to rot and taste unpleasant.

Why does the borer only seem to affect the fruit?

The adult moth specifically seeks out the rind of the mangosteen fruit to lay eggs, as the developing interior provides the perfect food source for the hatching larvae.

Plants it affects

• Mangosteen