Prevention of jackfruit tree trimming

Cutting hair to bore jackfruit is difficult to treat because the worms are deep in the trunk and branches. Instructions for early identification through punched holes, wood chips, sap flow and treatment by cleaning the orchard, light traps, catching worms, and properly covering treatment holes.

Summary: Stem borer is a silent but very dangerous pest on jackfruit. When you see a withered branch or a sap-oozing trunk, the worms have usually eaten deep inside the wood. Spraying outside the canopy is not nearly as effective if the perforations are not properly treated. This article guides how to detect early and prevent in three layers: orchard hygiene + catching adults + handling larvae in the trunk.

Applies to: Thai Changai jackfruit, red-flesh jackfruit, To Nu jackfruit in the Mekong Delta, Southeast and low Central Highlands.
Duration: Monitoring all year round, increasing inspection at the beginning of the rainy season and after harvest.
Difficulty level: Medium. It is necessary to patiently search for holes and handle each tree.
Estimated additional costs: 1-3 million VND per hectare per year for light traps, hole treatment chemicals and inspection labor.

How harmful is cutting your hair?

Adult hair clippers are beetles. Adults usually lay eggs on:

Cracks on the body shell.
Wounds caused by pruning, collision, peeling.
Dried branches and broken branches still hanging on the tree.
The trunk/branches are dense, rarely inspected.

After hatching, the larvae bore under the bark and then eat deeply into the wood. The larger the worm, the wider the chisel line. When the blood vessels are cut, the upper branches quickly wilt, the tree declines, and even the whole tree dies if the main trunk is damaged.

Difficult point: most of the worm's life cycle lies within the body. Therefore, spraying crop-protection products on the leaves cannot reach the worms.

Early recognition signs

Go to the orchard in the early morning or late afternoon, observe the trunk and main branches:

There are small holes in the shell, usually 2-8 millimeters in diameter.
There are wood chips or worm droppings extruding, yellow brown or black brown.
The casing around the hole has melted plastic.
The branches above the hole wither, the leaves turn yellow and fall off abnormally.
Chiseled branches sound hollow when gently tapped.

With jackfruit trees, there is a lot of white sap so the hole is sometimes covered by streaks of sap. Need to wipe gently to see the real hole.

Three layers of hair cutting room

Class 1 — orchard cleaning

This is the cheapest solution:

Remove dry branches, broken branches, and diseased branches.
Do not leave piles of dry branches in the orchard because they attract adult beetles.
Prune the canopy for ventilation, especially branches close to the trunk.
After cutting large branches, apply copper or lime based treatment on the cut.
Avoid scraping the skin or cutting the stem to stimulate fruit production.

Open wounds are places where hair clippers can easily lay eggs. The more broken branches and untreated cuts in the orchard, the higher the risk.

Grade 2 — Getting to adulthood

Adult hairdressers are often most active in the evening and at night.

Use light traps from 6-9 p.m., especially at the beginning of the rainy season.
Go to the orchard early in the morning and catch adults perching on trunks/branches.
Concentrate on checking dense trees, trees near the shore, trees with many dry branches.
You can gently shake low branches to detect falling adult beetles.

Capturing adults reduces the number of eggs laid. This method does not replace punch hole treatment, but helps reduce pressure for the next crop.

Layer 3 — Protect healthy plants

Weak plants are more susceptible to severe attacks:

Fertilize in a balanced manner, do not fertilize too much nitrogen to make the canopy dense.
Keep moisture stable in dry season.
Do not let the tree bear too many fruits.
After harvest, restore plants with organic waste + Trichoderma.

Healthy trees are not immune to hair loss, but are more tolerant and recover easily after removing harmful branches.

Handling when holes are detected

With damaged branches

If the hole is on a small or withered branch:

Remove branches 20-30 centimeters below the damaged location.
Split branches to catch larvae or pupae.
Take the branches out of the orchard to destroy them.
Cover the cut with copper or lime-based treatment.

Don't feel sorry for the heavily chiseled branch. Leaving it in the orchard is to keep the worm nest.

With main trunk or large branches

If the tree can still be saved:

Use a small knife to gently open the hole and take out the wood chips.
Use soft wire to thread along the chisel line to kill the worms if you can touch them.
Use cotton soaked in fumigant treatment/recommendation according to the label, stuff it into the hole.
Seal the hole with clay or grafting wax to keep the treatment in the chisel line.
Check again in 7-10 days. If there are new mites, treat a second time.

Do not spread treatment around the base. The goal is to deliver the drug into the correct path.

When the tree is seriously damaged

Severely damaged trees have the following signs:

The main body has many perforated holes.
Canopy wilting over 50 percent.
It sounds empty when you knock on it.
The base has continuous wood chips.

In this case, the stem should be cut down, split and destroyed. If you just cut it horizontally and leave it in the orchard, the larvae can still continue to develop into adults.

Inspection schedule for the year

The beginning of the rainy season

Set a light trap.
Check trunk/branch every 7 days.
Prune dry branches before prolonged rain.

In the middle of the rainy season

Watch for abnormally wilted branches.
Treat holes with new mites immediately.
Don't let the orchard get too dense.

After harvest

Cut fruit-bearing branches and diseased branches.
Scan large cuts.
Fertilize to restore plants.
General review of holes before new crop.

Monitor periodically

[ ] Number of trees with perforated holes in the orchard.
[ ] Hole location: main stem, level 1 branch, small branch.
[ ] Are there new wood chips after treatment?
[ ] Number of adult beetles caught in light traps.
[ ] The branch/tree has been removed and destroyed.

If the percentage of damaged trees is above 5-10 percent, the frequency of inspection should be increased to twice per week during the peak season.

Common mistakes

Only spray outside the canopy: worms are inside the stem, spraying outside the leaves is very ineffective.

Do not cover the hole after inserting the treatment: the treatment evaporates quickly, not effective enough in the cloudy line.

Leave the damaged branch in the orchard: the worms will continue to pupate and fly out to cause further damage.

Scrape the shell, chop the stem to stimulate fruit: create a wound for the hair clipper to lay eggs.

Wait until the branch is wilted to treat it: by then the chisel line will be large, saving the branch will be much more difficult.

Take notes

Date of hole discovery.
The tree/lot is damaged.
Treatment measures: cut branches, thread wire, apply treatment, cut down.
Results after 7-10 days.
The time when light traps catch many adults.

Taking notes helps you know which seasons hair clippers appear strongly in your orchard, so you can set traps and check earlier next year.

References

*Prevention of stem cutting on fruit trees* — Long An Agricultural Service Center.
*Managing stem borers on fruit trees* — National Agricultural Extension Center.
*Production of jackfruit for export* — Department of Crop Production, 2023.