Pathogenic
Microbiology and
Epidemiology MCB
402)
Course co-ordinator: Odedara, O.O.
*1Department
of Microbiology, University of
Agriculture, Abeokuta, Nigeria (UNAAB)
Bacteria as plant pathogens
 Bacteria are ubiquitous and physiologically
diverse
 Most bacteria plant pathogens possess
common morphological characteristics such as
slightly curved rods with rigid cell walls
 Some have facultative anaerobic metabolism
 Bacteria plant pathogen could be Gram
positive or Gram negative
 Acidovorax, Agrobacterium and Bulkholderia
are examples are examples of Gram negative
ones
Materials and Methods
 The few Gram positive pathogens are
mainly contained in the genera
Curtobacterium and Streptomyces
Significant bacteria plant
pathogens
 Gram negative genera (Agrobacterium)
-A member of the family Rhizobiaceae
-found in the soil and plant roots
-some are phytopathogenic
-they invade the stem, crown and the root of
dicotyledonous plants
-Some species cause the transformations of plant
cells into tumour cells e.g. Agrobacterium
tumefaciens
 Gram positive genera
- Member of the family
Streptomycetaceae
 Produces vegetative
hyphae
- Widely distributed in soil
- E.g Streptomyces
ipomoeae which causes
scab in sweet potato
Transmission of plant
bacteria pathogens
 Dissemination is by:
- Water
- Wind
- Soil movement etc.
Other plant pathogens include:
- Fungi
- Viruses
 They can be transmitted through similar
routes as in bacteria
 Control of plant pathogens include:
- Cultural methods
- Sanitary measures
- Biological controls
- Roguing etc
Selected crop diseases of
plants
 Cassava mosaic disease (CMD)
- Characterised by formation of irregular yellow
patches
- Known as mosaic
- Caused by African cassava mosaic virus
(ACMV)
- Transmitted by whiteflies (Bemisia tabaci)
- Known to cause about 0-82% crop loss
- Had been reported throughout all cassava
growing areas of Africa
Control of CMD

-
By:
Phytosanitation
Vector control
Use of resistant cultivar etc.