disease

1. Citrus Canker

2. Contents
• What is the disease?
• Symptoms
• Causal organism
• Disease Cycle
• Control measures

3. What is the disease?
• A disease is a particular abnormal condition that aff
ects part or all of an organism and that consists of a
disorder of a structure or function.
• A condition of the living animal or plant body or of
one of its parts that impairs normal functioning and
is typically manifested by distinguishing sings and sy
mptoms.

4. Symptoms
• It is the most serious bac
terial disease.
• The disease affects the le
aves, twigs, thorns and frui
ts.
• All green parts and matu
ring fruits become more or
less covered with brown sc
abby spots surrounded by
dark-brown glossy margins.

5. • The lesions appear as s
mall yellowish spot, which
enlarge to a diameter of 3
or 4 mm. and become rais
ed and rough or spongy an
d turn brown.
• The market value of the
fruits is reduced, because
of the appearance of scabb
y lesions.

6. Causal organism
• Citrus canker is caused by Xanthomonas citri.
• It is a gram negative, monotrichous, capsulated bac
illus which is strictly aerobic in nature.
• It is 1.5-3 micrometer in length and 0.5-1.5 microm
eter in breadth.
• The bacteria does not produce endospores and can
not reduce nitrates.

7. • It is aerobic.
• Colonies on beef agar are circular, straw yellow to a
mber yellow.
• Nitrates are not reduced.
• The bacterium enters through stomata and wounds.

8. • The disease is favoured by mild temprature and we
t weather.
• From the cankers, disease spreads by driving rains
and insects.
• Man is also an important agent of dissemination th
rough infected nursery stock.

9. Classification of pathogen
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Xanthomonadales
Family: Xanthomonadaceae
Genus: Xanthomonas
Species: Citri

10. Disease Cycle

11. Control measures
• Various methods are adopted for the control of citr
us canker.
• Some important measures are as follow :
1) Complete destruction of diseased plant by burning
them.
2) Use of disease free nursery stock for planting.

12. 3)Spraying the plant before planting with 1% Bordea
ux mixture.
4)Antibiotic spray with streptomycin, phytomycin.
5)Spraying leaves with neem-cake (160 lbs/acre).
6)Disease resistant varieties.

13. References
• The DBS Handbook of Botany by : Lalit Kum
ar Dwivedi.
• Fungi and Allied organisms by : P.D. Sharma
•Plant pathology by : B.P.Pandey
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