Dispersal of plant pathogens

Dispersal of plant pathogens

1. DISPERSAL OF PLANT PATHOGENS B. PAVAN KUMAR NAIK Assistant Professor Department of Horticulture

2. second link in infection chain is the dissemination of plant pathogens. Dispersal , dissemination or transmission ?

3. Fungi Bacterial diseases Viral diseases

4. The dispersal of infectious plant pathogens in space occurs through two ways: Autonomous or direct or active dispersal. 2 . Indirect or passive dispersal.

5. I) Autonomous or direct or active dispersal Seed as the source of autonomous dispersal : a) Contamination of the seed b) Externally seed borne c) Internally seed borne

6. 2) Soil as a means of autonomous dispersal Dispersal in soil : Contamination of soil ii) Growth and spread of a pathogen in soil iii) Persistence of the pathogen in soil b) Dispersal by the soil:

7. 3) The plant and the plant organs as a means of autonomous dispersal : Late blight of potato was introduced in North America and in Europe through seed tubers brought from the native source of the in South America.

8. II) Passive or Indirect dispersal Animate agents: a) Insects: Fungal diseases/Bacterial diseases/Viral diseases/Mycoplasma diseases. b) Mites c) Fungi d) Nematodes:Bacterial diseases/Fungal diseases/Viral diseases/NEPO viruses/NETU viruses

9. e) Human beings: Transportation of seeds (seed trade ) Planting diseased seed materials During adoption of normal farming practices By use of contaminated implements By use of diseased grafting and budding material

10. f) Dispersal by phanerogamic parasites g) Dispersal by birds h) Farm and wild animals

11. 2) Inanimate agents: Wind: Fungi/Nematodes/Bacteria/Viruses and phytoplasmas . b ) Water:

12. PHENOMENON OF INFECTION/ INFECTION PROCESS It is the third link in the infection chain after survival and dispersal of inoculum. Inoculum potential

13. The success of process of infection depends on: Host factors Susceptibility of host: Disease proneness of the host : 2. Pathogen factors Virulence / aggressiveness of the pathogen: High multiplication rate of the pathogen : Proper inoculum potential:

14. 3. Environmental factors Process of infection can be grouped into three stages, i.e., pre-penetration, penetration and post-penetration.

15. 1. PRE-PENETRATION Active invaders and 2.Passive invaders

16. PENETRATION Indirect Penetration:Wounds /2. Natural openings/

17. PLANT DISEASE EPIDEMIOLOGY

18. Disease Pyramid

19. Essential components/conditions for an Epiphytotic Host factors Distance of susceptible plants from the source of primary inoculum Abundance and distribution of susceptible hosts Disease proneness in the host due to environment Presence of suitable alternate or collateral hosts

20. 2. Pathogen factors: Presence of virulent/aggressive isolate of a pathogen High birth rate Low death rate of the pathogen Easy and rapid dispersal of the pathogen Adaptability of the pathogen

21. 3. Weather factors Weather conditions such as, optimum temperature, moisture, light, etc., are very essential for the development of an epidemics. Science which deals with the relationship between weather and epiphytotics is called metereopathology .