Prevention of fruit borers for jackfruit

The jackfruit borer (Conogethes punctiferalis) bores into the shell, eats the rice inside, completely damaging the fruit. Instructions for fruit bags + traps + rotating treatment for Thai jackfruit in the Mekong Delta.

Summary: Jackfruit fruit borers are the most destructive pests after yellow and black flies. Once the worms have burrowed into the fruit, it cannot be saved — the fruit's flesh is dark and damaged. Early fruit bagging is the most effective method (80-95 percent against borers). This article guides three layers of prevention — fruit bags + pheromone traps + periodic spraying — for commercial jackfruit orchards.

Applies to: Thai Changai jackfruit, To Nu jackfruit, red-fleshed jackfruit in the Mekong Delta, Southeast, and low Central Highlands.

Duration: Track from fruit set to harvest.

Difficulty level: Medium.

Estimated additional costs: 4-7 million VND per hectare per crop (bag of fruit + treatment).

Characteristics of jackfruit borers

*Conogethes punctiferalis* is the larvae of a moth. This worm also attacks durian and some other fruit trees. On jackfruit:

• Moths lay eggs on the skin of young fruit, usually at the stem.
• Eggs hatch into larvae in 4-7 days.
• The worm bores into the fruit, eating the rice + fiber inside.
• Life cycle 30-45 days from egg to flower.
• Pupates in fallen fruit at the base or on branches.

Signs of fruit decay:

• Small hole in shell — 1-3 millimeters in diameter.
• worm feces (mites) push out the hole — dark brown powder.
• The fruit has a lot of sap around the hole — jackfruit has a characteristic white sap.
• Fruit falls prematurely or rots from the inside when the worm infestation is severe.

Three layers of rooms

Grade 1 — Fruit bag (highest efficiency)

Baking fruit is the most effective way to prevent it:

Time when:

• Changai Thai jackfruit: when young fruit reaches 0.5-1 kg (30-45 days after fruit set).
• To Nu Jackfruit: 0.3-0.5 kg when fruit.

Bag type:

• Specialized paper bags (paraffin paper or 2-layer paper): durable for 3-4 months. Cost 1,000-3,000 VND per bag.
• Mesh cloth bag: durable, reusable. Higher cost (5,000-15,000 VND per bag) but cheap in the long term.
• Perforated plastic bags: cheapest but ineffective — easily causes moisture in the bag to cause fungus.

Coating technique:

• Check the fruit for no signs of decay before wrapping.
• Wrap the fruit + part of the stem with paper.
• Tie the stem side tightly with built-in string.
• Especially with large jackfruit (over 3 kilograms): need a ventilated mesh to prevent moisture accumulation.

Layer 2 — Pheromone trap

Traps reduce the number of male butterflies in the orchard → reduce mating rate → reduce the number of eggs:

• Place 5-10 *Methyl eugenol* pheromone traps per hectare.
• Hang the trap 1.5-2 meters high in the canopy.
• Each trap maintains 6-12 weeks. Replace when run out.
• Place around the perimeter of the orchard to catch butterflies from the outside in.

Effectiveness: 30-50 percent deep pressure reduction. Combine with fruit bags for maximum effectiveness.

Class 3 — Spraying

Spraying for trees without fruit cover + preventive spraying phase 1-2:

Suitable active ingredients:

• *Emamectin benzoate* — biological, effective against borer larvae.
• *Spinetoram* — biological, safer than pyrethroids.
• *Chlorantraniliprole* — highly effective, low resistance.

Room spraying:

• Phase 1: when the young fruit reaches the size of an egg (20-25 days after fruit set).
• Phase 2: 30-40 days later, before fruit packaging.
• Third stage (if not covered): fruit set 60-70 days later.

Harvest method: at least 30 days before harvest — ensuring reduced drug residue.

Clean the orchard — remove worm nests

Good hygiene reduces deep pressure for the next crop:

• Collect fallen fruit under the tree every 2-3 days. Fallen fruit still has larvae → outbreak.
• Bury or burn — do not throw in a pile.
• Cut pest branches in the canopy — where butterflies stay at night.
• Cleaning at the end of the season — don't leave any fruit behind.

Periodic monitoring

• [ ] Check young fruit + large fruit weekly — look for holes.
• [ ] How many butterflies does the pheromone trap catch — count.
• [ ] Percentage of fallen fruit showing signs of decay.
• [ ] Condition of the left bag — is the bag torn, wet or damaged?

When there was an epidemic in the orchard

If more than 10 percent of fruit is detected to be damaged:

Step 1: cut + destroy severely damaged fruit. Take it away from the orchard to burn or bury.

Step 2: spray *Emamectin benzoate + Chlorantraniliprole* in combination throughout the orchard.

Step 3: bag the fruit for a new batch of fruit immediately.

Step 4: increase the number of pheromone traps — add 5 traps per hectare.

Step 5: 14 days later, check. Repeat processing if there are more.

Compare fruit wrapping and spraying

→ Fruit bags have a higher cost but are highly effective + clean of residue. Export orchards should cover fruit.

Common mistakes

Spraying instead of fruit bags: low efficiency + residue → difficult to export.

Late fruit bagging (after the worms have laid eggs): worms inside the fruit while bagging — cannot be saved.

Covered in sealed plastic: fruit lacks air, susceptible to fungus + rot.

Let the fruit fall under the tree: a worm nest for the next crop.

Place a trap in the middle of the orchard: focus deep in the middle, destroy more. Place around the orchard perimeter.

Take notes

• Number of bagged and unwrapped fruit in the crop.
• Proportion of fruits with post-harvest worms.
• How many butterflies does the trap catch each week?
• Spray + day.
• Cost comparison: fruit bags vs. spraying.

References

• *Prevention of fruit borers on fruit trees* — Plant Protection Department, 2022.
• *Production of jackfruit for export* — Department of Crop Production, 2023.

Related articles

• Instructions for productive jackfruit care
• Prevention of black fiber phenomenon on jackfruit
• Prevention of jackfruit tree trimming
• Calculate fertilization recommendations