Instructions for stem borer prevention for pepper

The stem borer (Lophobaris piperis) eats underground inside the pepper stem, weakening the plant and causing it to die. Difficult to detect before it's too late. Instructions for recognizing early signs, measures to prevent and treat insect-infected trees for Central Highlands orchards.

Summary: Pepper stem borer is a silent enemy — causing no obvious symptoms, only detected when the tree begins to dry out its branches. The characteristic of underground tunneling in the trunk causes the tree to lose the ability to transport sap. A severely damaged pole can die in 6-12 months. This article focuses on three signs of early detection and prevention along the deep life cycle.

Applies to: Pepper orchards in the Central Highlands (Dak Lak, Gia Lai, Dak Nong) and the Southeast.
Duration: Year-round room, monthly inspection.
Difficulty level: Medium. The important thing is early detection.
Estimated additional costs: 2-3 million VND per hectare per year.

Agents and life cycle of stem borers

*Lophobaris piperis* is a beetle (heliotrope beetle) — common on Vietnamese pepper. Features:

The adult worm is 4-6 millimeters long, dark brown in color, with a long trunk like an elephant's trunk.
Lay eggs in stem cracks or leaf axils.
The larvae bore into the stem, eating the plastic inside. The chisel line is 5-30 centimeters long.
Pupates inside the body, then turns into an adult worm.
Life cycle 60-90 days — 3-4 generations per year.

The pepper tree is infected with stem borers:

The plastic circuit in the body is damaged.
Trees cannot transport water and nutrients.
The branches begin to dry from the top down.
Yields decreased by 30-50 percent during the season.
Can completely die if the worm destroys many lines in the main body.

Three signs of early detection

Small hole on the body

1-2 millimeter round hole, may contain dry resin or sawdust.
Location is usually in stem nodes, leaf axils, or old cracks on the stem.
Observe the main stem from the base to the top — don't ignore the hidden part in the canopy.

The mites push out of the hole

Large worms bore into the stem, pushing small mites out.
Mites resemble brown powder, sometimes even dry resin.
Ripe around the body looking for mites — especially on the lower joints.

Dry branches for unknown reasons

The branches begin to dry at the tips, with no symptoms of fungal disease.
The leaves are dry but not yellow from the edges (like mottled spots) — dry evenly.
The lower branch is strong, the upper branch is dry — the worms have bored veins that carry the sap to the top.

When you see these three signs, immediately check 5-10 neighboring pillars.

Deep Lifecycle Room

orchard cleaning

Cut diseased branches and dry branches — where adult worms reside.
Clean up peeling tree bark — the place where worms lay their eggs.
Whitewash the base of the pillars every quarter — reduce cracks as spawning areas.

Spray the room periodically

Early rainy season (April-May) — the time when adult worms are most active:

Spray *Chlorpyrifos* or *Cypermethrin* (synthetic pyrethroid insecticide) on the body.
Spray evenly from root to tip.
Repeat after 30-45 days during the rainy season.

End of the rainy season (October-November):

Final spraying to kill adult worms preparing to overwinter.

Protect natural enemies

Natural enemies of stem borers:

Parasite wasps: lay eggs in larvae.
Insectivores: caterpillars, warblers.

Protect by:

Do not spray unnecessarily with broad-spectrum crop-protection products.
Plant trees on the edge of the orchard with small flowers.
Leave supporting trees as bird shelters.

Treating decayed trees

The budding tree has (1-3 holes)

Step 1: inject treatment into the perforated hole.

Mix *Chlorpyrifos* concentration 0.2-0.3 percent.
Use a needle to inject 0.5-1 milliliter of solution into each hole.
Clog the hole with plastic soil after injection.

Step 2: spray the whole tree.

Spray *Chlorpyrifos* or combine *Chlorpyrifos + Cypermethrin*.
Spray evenly on body and spread.

Step 3: repeat after 14-21 days.

Step 4: organic fertilizer + plant recovery nutrients.

The tree is severely damaged (many perforated holes + widespread dry branches)

Low rescue rate. Decision:

Continue to treat if the pillar is still valid + the disease has not spread to the main stem.
Dig and replace pillars if the main body has been destroyed. Pit soil treated with lime + Trichoderma before replanting.

Areas with many affected trees

When the orchard has 10 percent or more of the pillars damaged:

Spray the entire orchard according to the regimen 3 times, 21 days apart.
Rotate active ingredients.
Improve orchard hygiene — cut diseased branches, clean stem cracks.

Periodic monitoring

[ ] Check the main stem of 10-20 random posts each month. Find the perforated hole.
[ ] Wipe your hands around your body looking for sawdust.
[ ] Observe dry branches for unknown reasons.
[ ] Count the number of pillars to detect worms — draw a map of the orchard.

Common mistakes

Spray on leaves instead of stems: adult worms lay eggs on stems. Effective new body spraying.

Skip checking the stem: only observe the leaves, do not see small holes in the stem.

Injecting too low a dose: cannot kill the larvae in the body.

Do not cover the hole after injection: drug evaporates, low effectiveness.

High nitrogen fertilization: the tree's bark is soft, susceptible to egg-laying by worms.

Take notes

The orchard map marks the damaged pillars.
Date of discovery + number of holes.
Treatment method + results after 30 days.
Active ingredient for room spray + date.

References

*Stem borer control on pepper* — Plant Protection Department, 2022.
*Integrated pest management for pepper* — Vietnam Pepper Association (abbreviated name VPA), 2023.