Integrated pest management IPM in Orange orchards

Integrated pest management on oranges is not about giving up crop-protection products, but about using crop-protection products at the right time, to the right target, and at the right dose. Guidance on the five pillars of integrated pest management applied to orange trees in Ha Giang, Hoa Binh, and the Mekong Delta.

Summary: Vietnam's orange orchards are often "caught in a cycle of crop-protection products" — spraying a lot, pests are resistant, spraying more. As a result, costs increase, quality decreases, and soil and trees weaken. Integrated pest management (abbreviated English name IPM) is a way to break this cycle. This article teaches five pillars that apply specifically to oranges — not general theory but practice in the orchard.

Applies to: Ha Giang gourmet oranges, V2 Hoa Binh oranges, Mekong Delta diamond oranges, Cao Phong oranges. Business orchard from the 3rd year onwards.

Duration: Apply year-round, prioritizing important growth milestones.

Difficulty level: Medium. Need to change habits from periodic spraying to threshold spraying.

Estimated additional costs: Reduce 30-50 percent of crop-protection product costs compared to traditional periodic spraying.

Why is it necessary to have integrated pest management for oranges

Orange groves have a complex growth cycle — many buds, long flowering, and fruit development for 6-9 months. Pests and diseases on oranges are diverse:

• Leafminers, mealybugs, yellow jacket flies, stem borers, fruit borers — about insects.
• Citrus ulcers, anthracnose, scars, yellow leaves and root rot — about fungal and bacterial diseases.
• Greening (greening disease) — the most dangerous disease caused by bacteria transmitted by psyllids.

If you spray crop-protection products on a regular schedule "spray every 15-20 days", the consequences:

• Kills natural enemies — ladybugs, wolf spiders, parasitic wasps. Loss of natural defense line.
• Pests are resistant to drugs — must increase dosage or constantly change drugs.
• Analysis of crop-protection product residues — cannot be exported or sold at low prices.
• High costs — an average Ha Giang orange orchard costs 25-40 million VND per hectare per year for treatment.

Integrated pest management does not skip crop-protection products but uses crop-protection products at the right time, to the right target, at the right dose — combined with other measures to reduce epidemic pressure.

Five pillars of integrated pest management in oranges

Pillar 1 — Healthy trees

Strong orange trees are less susceptible to pests than weak trees. This pillar is the foundation for everything else:

• Choose resistant varieties — Ha Giang king oranges tolerate cold well, diamond oranges tolerate heat well. Plant the correct regional varieties.
• Balanced fertilization, organic priority — nitrogen only 30-40 percent of total fertilizer, phosphorus and potassium balanced.
• Water evenly, do not shock the plant. Water-shocked plants = soft tissue = pests can easily enter.
• Prune branches for ventilation — dense orchards are nests for pests and diseases.

Pillar 2 — Protecting natural enemies

Natural enemies in the orange orchard are the most powerful natural weapons:

• Ladybugs eat mealybugs and scale aphids. A ladybug eats 20-40 aphids every day.
• Wolf spiders and stalking spiders eat grubs of all kinds.
• Parasite wasps lay eggs in leafminers and aphids.
• Weaver ants eat many types of pests but need to control the quantity.

How to protect:

• Spray locally, do not spray the whole orchard when not needed.
• Prioritize selective drugs that are less harmful to natural enemies — *Pyriproxyfen* (insect growth regulator) instead of *Cypermethrin* (synthetic broad-spectrum pyrethroid).
• Plant orchard plants with small flowers — echinacea, peanut grass, basil — as shelter for natural enemies.

Pillar 3 — Regular observation and threshold counting

This is the biggest difference compared to periodic spraying. Check every 7-10 days:

• Count the number of leafminers on 30 random young leaves.
• Count the number of mealybugs on 10 random branches.
• Count the number of fruits with holes in 50 random fruits.
• Observe citrus psyllids on buds — transmitters of greening disease.

Specific spray threshold:

Below threshold — do not spray. Above the threshold — spray on the right target, don't spray randomly.

Pillar 4 — Mechanical and biological measures

Before thinking about medication, use low-impact measures:

• Cut diseased branches and carry them away from the orchard to burn.
• Bag fruit in paper bags or mesh bags with exported plants — 80-95 percent effective against yellow flies.
• Set yellow fly traps with pheromones or *Methyl eugenol* bait — 5-10 traps per hectare.
• Release parasitic wasps if there is a supply — effective control of leafminers.
• Whitewash the base of the tree twice a year — prevent fungus and repel egg-laying insects.

Pillar 5 — Use treatment correctly

When treatment is needed, apply the principle:

• Choose the right active ingredient for the right target. Do not use broad-spectrum drugs when selective drugs are available.
• Spray the disease area locally, do not spray the entire orchard.
• Rotate 3-4 different groups of active ingredients throughout the year to avoid resistance.
• Spray in the cool afternoon, do not spray before rain or strong sunlight.
• Comply with pre-harvest quarantine period.

Calendar applies by year for oranges

After harvest (after January-February)

• Cut pest branches and clean the orchard.
• Organic fertilizer and fused phosphate.
• Whitewash tree stumps.
• Check natural enemies — the number of ladybugs and spiders after the harvest season.

Blooming and flowering (February-April)

• Count psyllids weekly on buds — the most dangerous object at this stage.
• Prevent worms from casting spells when buds appear.
• Do not spray when flowers are blooming.

Fruit setting and fruit growing (April-September)

• Cover the fruit when it is as young as an egg if the orchard has yellow flies.
• Set a pheromone trap.
• Monitor mealybugs and scale bugs every 2 weeks.

Mature fruit (October-January)

• Check for yellow flies and fruit borers.
• Avoid spraying in the 30 days before harvest.

How to apply to orchards that are being sprayed periodically

Converting from periodic spraying to integrated pest management needs to be done gradually:

Year 1: Reduce spray frequency by 30 percent. Start counting thresholds for the 2-3 most common objects.

Year 2: Additional 30 percent off. Additional mechanical measures — fruit bags, pheromone traps, whitewashing.

Year 3: Threshold management for all subjects. The amount of treatment is reduced by 50-70 percent compared to the original.

Note: natural enemies need 1-2 years to fully recover after heavy spraying. Don't be discouraged if you see more pests and diseases than usual in the first year of conversion.

Common mistakes

"Spray the room to be sure": is the cause of the drug spiral. Proper prevention is mechanical measures and healthy plants.

Use broad-spectrum drugs for all situations: kill natural enemies along with pests.

Not counting before spraying: wasting treatment and effort.

Abandon bagging fruit because it's "wasting effort": bagging fruit is many times more profitable than the cost of bagging.

Planting a single type on a large area: Pure orange orchards are more difficult to prevent epidemics than mixed orchards.

Monitor and record

• Number of applications per year — target 50 percent reduction after 2 years of application.
• treatment costs per hectare — compare this year with last year.
• Detection object, date, countable threshold.
• Effectiveness of mechanical measures — how much traps catch, what percentage of fruit bags reduce yellow flies.
• Yield and quality of fruit per crop.

References

• *Integrated pest management in citrus* — Plant Protection Department, 2022.
• *Integrated pest management manual for oranges* — Food and Agriculture Organization of the United Nations (FAO) Vietnam, 2021.
• *Prevention of greening disease on citrus* — Plant Protection Institute, 2023.

Related articles

• Pest control for oranges
• Prevention of citrus ulcer disease and scar disease
• Instructions for caring for orange orchards during harvest
• Techniques for pruning branches and creating canopy for orange trees