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Common Florida Citrus Diseases

Below is a list of common pathogens that may affect citrus varieties around Florida.
Please consider submitting samples for diagnosis through the SWFREC Diagnostic Clinic if you suspect a problem.​

Citrus Greening (Huanglongbing, HLB)

Causal Agent: bacteria, Candidatus liberibacter 

Vector: Asian citrus psyllid (Diaphorina citri)

Symptoms: asymetric blotchy bottling of leaves with multiple shades of green, mishapen green fruits that do not ripen before falling prematurely.

There is also "green islands" sumptom where dark green areas get reduced to small dark green dots. Mottled leaves may be thicker and more leathery and have corky raised veins. Some of these syptoms ressemble zinc patterned deficiency. The difference is diseased trees have symptoms occuring in random manner, whereas nutrient issues happen uniformly.

Useful Links

UF Extension

USDA regulatory info

Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

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Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

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Citrus Canker

Causal Agent: bacteria, Xanthomonas axonopodis pv. citri

Symptoms: Leaf lesions range from 2-10mm and have raised concentric circles on underside of leaf. They often have water-soaked margin and yellow halo. Yellow halo eventually changes to dark brown or black. Lesions always penetrate through both sides of leaf.

Fruit lesions are similar, 1-10mm in size, large lesions can penetrate a few millimeters into rind. Lesions may coalesce. Texture of lesion may include corky appearance and cracking as it ages.

Useful Links

UF Extension

IDTools Factsheet

USDA regulatory info

Canker on fruit
Canker on fruit

citrus canker sumptoms on grapefruits

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Citrus canker on leaf
Citrus canker on leaf

canker lesions and chlorosis on leaf

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Canker on fruit
Canker on fruit

citrus canker sumptoms on grapefruits

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Greasy Spot

Causal Agent: fungus, Mycosphaerella citri

Symptoms: foliar spots that appear yellow at first, with a slightly raised area on lower surface, and later these spots become brown or black, with a slightly "greasy" appearance

Useful Links

UF Extension

IDTools fact sheet

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Citrus Black Spot

Causal Agent: fungus, Phyllosticta citricarpa

Symptoms: three main spot symptoms: virulent spot, cracked spot, hard spot. Virulent spot is small red spots, cracked is a thicker blister/scab like appearance, hard spot is the most typical symptom, appears usually around color change. All of these lesions range from 3-10mm in diameter. Younger lesions are small and reddish, with yellow halos. Foliar lesions are not as common as fruit symptoms. 

Useful Links

UF Extension

IDTools Factsheet

USDA Regulatory info

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Citrus Blight

Causal Agent: unknown

Symptoms: a "wilt-and-decline" disease of citrus

It can start as mild wilting and have a grayish hue in the foliage and have zinc deficiency symptoms.

The trees can then rapidly decline with twig dieback, off-season flowering, and small fruit.

It may be difficult to determine whether this citrus blight is the cause of the symptoms on a tree due to the widespread HLB and its extreme symptoms, and Citrus tristeza virus similarities.

The best ways to determine citrus blight diagnosis is 4 part:

1. High zinc content in trunk bark and wood

2. Presence of amorphous plus in the xylem

3. failure to absorb water injected into the trunk

4. presence of blight-associated citrus proteins in roots and leaves

Information from:

UF Extension

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Citrus Leprosis

Causal Agent: virus, Citrus leprosis virus (CiLV)

Vector: Asian citrus psyllid (Diaphorina citri)

Symptoms: foliar and fruit lesions. Symptoms appear 1-2 months after mite vector inoculates. Typical lesions are circular with dark brown central mite feeding spot, 2-3mm in diameter. Feeding spot is surrounded by a chlorotic halo. Lesions may coalesce, and crack in high temperature conditions

Useful Links

UF Extension

IDTools Factsheet

Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

press to zoom

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Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

press to zoom
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Citrus Tristeza Virus (CTV)

Causal Agent: virus

Vector: Aphid

Symptoms: various symptoms and often asymptomatic. The most distinct ones are quick decline, stem pitting, and seedling yellows.

Useful Links

UF Extension

IDTools Factsheet

Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

press to zoom

press to zoom

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Asian Citrus Psyllid (ACP) nymph
Asian Citrus Psyllid (ACP) nymph

ACPs transmit the HLB bacteria to all citrus varieties

press to zoom
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Brown Rot

Causal Agent: fungus, Phytophthora nicotianae or Phytophthora palmivora

Symptoms: rotting appears on mature or nearly mature fruit, starts with leathery lesions that may have water-soaked appearance. They are olive brown, have an odor, and may turn soft from secondary infections. Sometimes infection spreads to twigs, leaves, and blossoms.

Environment: when conditions are cool and wet, and to fruit closest to the ground because phytophthora spores are splashed from soil during rainstorms and infections develop under continued wet conditions.

Useful Links

UF Extension

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