Huanglongbing(HLB)
Symptomsin Florida
Hilda D. GómezPlant Pathologist
HLBENVIRONMENTTIME
PATHOGENHOSTVECTOR
• A fastidious, phloem-limited Gram-negative bacterium• Irregularly distributed inside the host • Final identification using PCR• In Florida: Candidatus Liberibacter asiaticus causing Asian
form
PATHOGEN
ENVIRONMENT
• The Asian form occurs in warm climates and low altitudes (27-32 °C)
• Symptoms are more evident during the cooler months of the year
• Citrus cultivars grown in different areas could show different symptoms
• Symptoms: 2 months - 2 years (unclear)
• Symptoms observed in the present could be the expression of infections that occurred one or more years in the past
• This long and unclear latency period results in delayed disease diagnosis and pathogen detection
TIME
VECTOR Asian citrus psyllid
Lateral notching
Sooty mold
Burnt tip
RESULTING FROM THE PSYLLID FEEDING DAMAGE
• Huanglongbing = yellow shoot
• Host range: all citrus varieties and their hybrids, and some citrus relatives in the Rutaceae family
• None of the HLB symptoms are exclusive for the disease
• The most diagnostic symptom: blotchy mottle (common on all varieties)
• Other symptoms add to field detection
• Symptoms better observed in the interior part of the canopy
HOSTSYMPTOMS
Blotchy mottledistinctive symptom on leaves
Upper Lower
Citrus aurantium
ASYMMETRICAL
Citrusmacrophylla
Crosses lateral veins
Limited by the mid vein
Citrus limon
Blotchy mottle usually confused with
citrus leafminer feeding damage
Citrus x paradisi
Blotchy mottleprogression
EARLY
ADVANCED
Citrus aurantiifolia
Citrus maxima
Citrus reticulata
Citrus hystrix
X Citrofortunella microcarpa
Severinia buxifolia
Thicker leaf
Yellow veins Corky veins
“Rabbit ears”
“Green islands”
Multiple off season flowers
“Nutrient deficiencies”
HLB
Sectoring Dieback
Decay of root system, decline in vigorCitrus maxima
Severe leaf and fruit drop in a
commercial grove
Citrus sinensis
Symptoms on fruit
Citrus maxima
Vascular stain
Aborted seed
Citrus x paradisi
Rating of suspect samples (USDA)
High Classic HLB mottleZinc-like deficiency. Yellow veins. Corky veins. Misshapen or oddly colored fruits.
Medium Non-classic mottleYellow veins. Vein corking. Chlorotic leaves. Zinc deficiency.
Low Zinc and other general deficiencies. Mottling resulting from insect injury, fungal diseases, and mechanical damage. Naturally senescing leaves. Genetic variegation.
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