critical severity

Citrus Greening (Huanglongbing)Identification & Treatment Guide 2026

Candidatus Liberibacter asiaticus · Family: Rhizobiaceae

Citrus greening (HLB) is caused by Candidatus Liberibacter asiaticus, spread by the Asian citrus psyllid. Symptoms include blotchy yellow mottling (asymmetric), lopsided small bitter fruit, and tree decline over 3-5 years. There is no cure. Manage with psyllid control (imidacloprid, kaolin clay), removing infected trees, and using certified disease-free nursery stock.

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Quick Diagnosis

critical

Citrus Greening (Huanglongbing)

Affects: leavesfruitrootsphloem
Peak Season: Year-round in tropical/subtropical regions; psyllid activity peaks during warm months and flush growth
Spread Risk: Moderate
Spread By: Asian citrus psyllid (Diaphorina citri), African citrus psyllid (Trioza erytreae), infected nursery stock, grafting

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Symptoms: What does Citrus Greening (Huanglongbing) look like?

Visual identification guide — tap each stage for details

Asymmetric blotchy yellow mottling on citrus leaf from HLB — Asymmetric yellow mottling — note irregular pattern across midrib

Small lopsided citrus fruit with asymmetric coloring from HLB — Lopsided fruit with uneven coloring and aborted seeds

Citrus tree with severe canopy thinning from advanced HLB — Tree decline with canopy thinning and branch dieback

Frühes Stadium

Asymmetric blotchy mottling on leaves
Yellow mottling appears on leaves but is asymmetric — not uniform on both sides of the midrib. This distinguishes HLB from nutrient deficiency. Mottling often appears on one branch initially.

Mittleres Stadium

Sectored yellowing and small fruit
Entire branches show yellow leaves (sectored yellowing). Fruit is small, lopsided, with asymmetric coloring (partially green). Seeds abort. Juice is bitter and low-sugar.

Spätes Stadium

Tree decline and dieback
Progressive canopy thinning. Root system collapses. Fruit drops prematurely. Tree becomes unproductive and eventually dies within 3-8 years of infection.

Causes: Why is my plant getting Citrus Greening (Huanglongbing)?

Environmental triggers and disease cycle

Asian citrus psyllid (Diaphorina citri) feeding and transmitting bacteria
Planting infected nursery stock
Grafting with infected budwood
Proximity to infected trees — psyllids fly 1-2 km

Disease Lifecycle

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Host Plant

Susceptible crop

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Pathogen

Candidatus Liberibacter

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Conditions

Year-round in tropical/subtropical regions; psyllid activity peaks during warm months and flush growth

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Infection

Penetrates tissue

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Symptoms

Visible signs

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Spread

Asian citrus psyllid (Diaphorina citri)

Often confused with: Citrus Canker. See our comparison guide.

How to Treat Citrus Greening (Huanglongbing)

Tick each step as you complete it — works offline too

🌿 OrganicSafe for all farms

Organic Treatment Steps

4 steps

Apply kaolin clay (Surround WP) at 30 g/L as foliar spray to repel psyllids during flush growth.
Release Tamarixia radiata parasitoid wasps as biological control of Asian citrus psyllid.
Remove and destroy confirmed HLB-infected trees to reduce inoculum for psyllid acquisition.
Maintain tree nutrition with foliar micronutrient sprays (Zn, Mn, Fe, B) to support infected trees.

🧪 ChemicalUse protective equipment

Chemical Treatment Steps

4 steps

Apply imidacloprid soil drench (0.5 g a.i./tree) every 3-4 months for systemic psyllid control.
Spray dimethoate or chlorpyrifos during psyllid flush periods for knockdown of adult populations.
Apply spinosad at 0.5 ml/L for psyllid control with lower non-target impact.
Note: No antibiotic or chemical cures the HLB bacterium in trees. All treatments target the psyllid vector.

Prevention & Seasonal Calendar

Year-round protection plan for your crops

Pre-Planting

Use only certified HLB-free nursery stock from screened mother trees
Control Asian citrus psyllid populations aggressively and continuously

Mid-Season

Scout regularly for psyllids and HLB symptoms — early detection is critical
Remove confirmed infected trees promptly to reduce disease pressure

Post-Harvest

Establish new plantings away from existing infected groves
Support area-wide psyllid management programs — individual efforts alone are insufficient

🌼 Companion Planting

These plants can reduce Citrus Greening (Huanglongbing) pressure when grown nearby:

guava

View full seasonal calendar for your region →

Frequently Asked Questions

Common questions about Citrus Greening (Huanglongbing)

Can HLB-infected trees be saved?

There is currently no cure for HLB. Enhanced nutrition programs (foliar micronutrients, improved soil health) can help infected trees remain productive longer, but they will eventually decline. Research into bactericidal trunk injections and heat treatments is ongoing but not yet commercially viable.

Is fruit from HLB-infected trees safe to eat?

Yes, the fruit is safe to eat and juice. However, it is typically small, lopsided, partially green, and the juice may be bitter with reduced sweetness. For processing (juice), HLB-affected fruit can still be used but at lower quality.

How quickly does HLB spread in an orchard?

In areas with high psyllid pressure, HLB can infect 100% of trees in an unprotected orchard within 3-5 years. The disease spreads faster in warmer regions with year-round psyllid activity and during periods of new vegetative flush when psyllids are most active.

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Related Disease

Citrus Canker

Xanthomonas citri subsp. citri

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Affected Plant

Citrus (Orange, Lemon, Lime)

Citrus sinensis / C. limon / C. aurantifolia

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Treatment Guide

Full Treatment Protocol

Detailed spray schedule & dosage guide

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