Presentation of Phytobacteriology

1. Citrus Canker
Xanthomonas axonopodis pv. citri
Presented By :
Srijana Bhandari
PLM-06-M 2016
Department of Plant Pathology
AFU, Rampur, Chitwan

2. Introduction
• The most serious bacterial disease, affecting all types of
important citrus crops.
• It causes necrotic lesions on fruit, leaves and twigs.
• Losses are caused by reduced fruit quality and quantity
and premature fruit drop.
• The market value of the canker affected fruits is very
much reduced.

3. Causal Organism :
Xanthomonas axonopodis pv. citri

4. Symptoms
•Necrotic lesions produced on young leaves, twigs and
fruits.
•Attack on leaves, twig, petiole, branches, fruit, thrones.
•Small, round, watery, translucent raised, yellow brown
spots on leaves and old branches.
•Spots- white to greenish & finally rupture–rough corky.
•Rough lesions surrounded by-yellow brown to green
raised margin & watery yellow halo.
•Crater like appearance is common in leaves.
•Fruit lesion become rough & corky.
• Defoliation

5. Symptoms

6. • Bacteria overseason in leaf, twig and fruit canker lesions.
• During warm, rainy weather they ooze out of lesions and, if
splashed onto young tissues, bacteria enter them through
stomata or wounds.
• Bacteria infect older tissues only through wounds.
• Several cycles of infection can occur on fruit; therefore, fruits
often have lesions of many sizes.
• Free moisture and strong winds seem to greatly favor the
spread of the bacteria.
• The disease seems to be much more severe in areas in which
the period of high rainfall coincide with the period of high
mean temperature, whereas it is not important in areas
where high temperatures are accompanied by low rainfall.
Development of disease

7. Disease Cycle
Fig: Disease cycle of citrus canker caused by Xanthomonas axonopodis pv. Citri

8. Management
• Strict quarantine measures should be practiced to
exclude the pathogen in canker-free citrus producing
areas.
• Selection of healthy nursery plants.
• Eradication of bacterium by burning all infected and
adjacent trees to prevent the spread of the pathogen.
• Prune the affected parts and spray with bactericide
(copper oxy-chloride).
• Wind break should be used to stop the movement of
pathogen due to wind.

9. References
• (2017, 5 17). Retrieved from
https://en.wikipedia.org/wiki/Citrus_canker.
• Agrios, G. N. (2006). Plant Pathology (Fifth ed.). Elsevier
Academic Press.
• Gottwald, T. R., Graham, J. H., & Schubert, T. S. (2002., August
12). Citrus Canker: The Pathogen and Its Impact.

10. Thank You !!!