Citrus Greening
Disease :essential data |
Disease Name,
Other Names, Crops
Affected Causative Agent, Synonyms,
Description of the Agent Symptoms,
Prevention and Treatment
Other
Comments |
| Disease name |
Citrus
greening disease |
| Other Names |
- Greening
- Blotchy mottle
- Decline (likubin)
- Dieback
- Leaf mottle
- Vein phloem degeneration
- Yellow branch
- Yellow shoot (huang lung bin)
|
Causative Agent
|
An uncharacterized Gram-negative
bacterium known as citrus greening disease bacterium for which the name
Liberibacter, also seen as Candidatus Liberibacter, has been
proposed |
| Synonyms |
None |
| Crops Affected |
Citrus crops |
| Description of the Agent |
The organism is poorly characterized. It is a filamentous Gram-negative
organism that has not yet been cultured under controlled in the laboratory,
It is transmitted by insects including:
- Diaporina citri
- Trioza erytreae
and by the plant dodder (Cuscuta spp.)
|
| Symptoms |
Citrus greening can be a systemic disease, especially in younger trees.
The first signs are seen in the leaves where yellowing along the veins
of leaves or a blotchy mottle of leaves. There is sometimes a chlorotic
mottle that resembles zinc or iron deficiencies. Fruit is misshapen
and bitter. It often falls prematurely and fruit that stays on the tree
does not color and seeds do not develop. The root systems do not develop
properly.
There are strain differences in symptoms with the Asian strains showing
more severe symptoms than the African strains.
|
| Prevention and Treatment |
There are relatively few treatments. One of the most effective
is heat treatment. Graftwood heated to 48-58°C (119-134°F)
for several minutes (conditions somewhat similar to pasteurization)
eliminate the disaease causing agent.
The most effective method of preventing the disease is to control the
insect vectors. This can be done by use of insecticides or (preferably)
with predatory wasps that lay their eggs in the larvae of the the vectors.
Agricultural practices including the careful selection of vector-free
production areas, good crop husbandry and careful selection of trees.
|
| Other Comments |
Citrus greening disease
is capable of being extremely destructive and causing catastrophic losses
of an important crop. Infection rates of up to 95% have been seen in Thailand
and crop losses of 100% have been seen in some areas of South Africa and
it has eliminated citrus production in some parts of the country. |