Some characteristics
Phloem limited
Fastidious bacteria- candidatus liberibacter asiaticus
Vector-psyllia- diaphorina citri
Associated
Kochs postulates fulfilled
In south africa
Candidatus liberibacter africanus Trioza erytrae 32 killed 27 half die 21 all survive
China
Gaudong province
How fruit look
Silver paste when pressed
Bitter
Aborted seed
Lopsided fruit
Symptoms appear
1/2 years after affected
3-5 years after infection
Alpha proteobacteria
Gram neg
Obligate intercellular parasite
Fastidious- cannot be cultured
Phloem limited
Economic importance
Citrus production abandoned
Control
Cirus certification scheme
Restrict planting materials from greening affected areas
Inoculum removal
Vector control- systemic
Psyllids
Nymps- waxy tubules- honeydew away from body
Nymphs- survive on young,tender leave stems
Nymphs only present when plant produce new leaves
Adults feed at 45
Where
95 sweet orange
Varities: pera,valencia,natal
Rootstocks-rangpur,swingle,sunki,cleopatra
Natural host
No risk
Calodendrumcapense
Sampling
Clausenaanisata - perdepis
Verpis lanceolata- wit ysterhout
Zanthoxylum capense- klein perdepram
Management disease triangle
Elimination of symptomatic trees
Insecticide treatment
Healthy,young trees
Insecticide applications
Figure
Main factors of management
Incidence if disease- moment when management initiated Age trees Period- control measures applied Size groove Distance from groove with no control Nr sprays per year Nr inspection per year Distance farm without management
Strategy- high maintain productivity in presence HLB
Establishment of groves on large surfaces,high tree density
Appropriate nutritional and irrigation practices
More intense efforts on grove borders for psyllid control
Regional HLB management- smaller farms
Research priotiries
Inspection improvement Systemic insecticides Low volume applications Entomopathogenic fungi Pheromones