1. Pathogenic Microbiology and Epidemiology MCB 402) Course co-ordinator: Odedara, O.O.

2. *1 Department of Microbiology, University of Agriculture, Abeokuta, Nigeria (UNAAB)

3. 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

4. Materials and Methods  The few Gram positive pathogens are mainly contained in the genera Curtobacterium and Streptomyces

5. 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

6.  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

7. Transmission of plant bacteria pathogens  Dissemination is by: -Water -Wind -Soil movement etc. Other plant pathogens include: Other plant pathogens include: -Fungi -Viruses

8.  They can be transmitted through similar routes as in bacteria  Control of plant pathogens include: -Cultural methods -Sanitary measures -Biological controls -Roguing etc

9. 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

10. Control of CMD  By: -Phytosanitation -Vector control -Use of resistant cultivar etc.