A brief Power Point Presentation on disease cycle for students about their academics on professional level.
Content for this compilation (Power Point Presentation) was collected from Different sources: Internet, books, social media, research papers, websites etc. and acknowledged all these sources to provide such a helpful content.
This Presentation was prepared and presented during Bachelors In Agriculture (Session 2014-2018) at "University College of Agriculture and Environmental Sciences, Baghdad-ul-Jadeed Campus, The Islamia University of Bahawalpur (Pakistan)" as an Assignment on the topic of "The Disease Cycle" with the collaboration of Student fellows Muhammad Amir Shehzad and Muhammad Farhan.
I hope, content might be helpful for student on academic level.
Best Regards
Muhammad Raza Ullah Tariq
2. Muhammad Raza Ullah Tariq
Muhammad Amir Shehzad
Muhammad Farhan
Presented BY:
Session: 2014-2018
Semester: 4th
Section: B
University College Of Agriculture And Environmental Sciences
The Islamia University Of Bahawalpur
Pakistan
4. Disease
Any disturbance in the physiological functions of living organism.
Disease Cycle
In every infectious disease a series of more or less distinct events
occurs in succession and leads to the development and
perpetuation of the disease and the pathogen. This chain of events
is called disease cycle.
8. Inoculation
It is the initial contact of a pathogen with a site of plant where
infection is possible.
Inoculum
The pathogen that lands on the host or
Any part of pathogen that can initiate infection.
9. Types of Inoculum
Primary inoculum
Survives during dormant period and causes the first infection.
Secondary inoculum
Produced from primary infections.
10. Landing or arrival of inoculum
Most pathogen carried to the host plant by wind ,insects and water.
Only a small number actually land on susceptible plants.
Vector born pathogen are much more efficient since the vectors have
an attraction for plants.
Examples:
Germination of spores and seeds(fungus)
Hatching of nematode eggs.
Attachment of pathogen to host(virus and bacteria).
Recognition between host and pathogen(pathogen recognizes the
host).
11. Penetration
Initial invasion of host by a pathogen.
Direct penetration
Penetration through natural openings
Penetration through wounds
12. 1 Direct penetration
Direct with haustoria
Direct subcuticular only
Direct intercellular mycelium
Direct intercellular mycelium with haustoria
Direct with appresorium (A), penetration peg (PP) and
intracellular mycelium (IM)
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18. The most common type of penetration by fungi and nematodes and
the only type by parasitic plants
Fungi uses a fine hyphae produced by a spore or mycelium or
penetration peg produced by an appressorium
This is formed at the point of contact by the host
19. The penetration is through mechanical force and softening of the
cell walls by an enzyme.
Most fungi form an appressorium at the end of the germ tube.
Then the penetration peg emerges from the flat surface of the
appressorium and pierces the cuticle and the cell wall.
20. The peg grows into the fine hyphae then reaches in normal diameter
once it is inside the cell.
A s in the case of apple scab, the fungus penetrates only the cuticle and
stays between the cuticle and the cell wall.
Parasitic plants also penetrate in the same way.
21. 2 Penetration through Natural
openings
Through stomata
Through lenticels (opening on fruits, stems and tubers-filled with loosely
connected cells which allow the passage of air)
Hydathodes (permanently open pores at the margins and tips of leaves)
22.
23. 3 Penetration through wounds
Through various types of wounds and injuries
Natural cracks between main and lateral roots
Openings made by fungus
24. Infection
Establishment of pathogen with vulnerable cells or tissues of the
host and obtain the nutrients from them.
Successful infection will produce symptoms.
25. Incubation period
The time interval between inoculation and appearance of
disease symptoms.
Latent infection
The state in which a host is infected by the pathogen but
does not show any symptoms.
26. Growth and Reproduction
The pathogen will grow and multiply within the infected host.
Fungi- spores
Viruses- replicated by the cell
Nematodes- reproduce by means of eggs
27. Dissemination of pathogen
While airborne-spores touch with wet surfaces-get
trapped-air movement stops/ rains- washed out
From the air- brought down by rain drops
Winds also helps spreading by blowing away rain
splash droplets containing pathogens.
Pathogens are disseminated by several ways:
By Air
28. Transmitted by insects when they feed from plant to plant.
Nematodes can also transmit viruses internally.
By Water
Pathogens in the soil-dissemination by rain/ irrigation water that moves
on the surface/ through soil.
By insects , nematodes & other vectors
29. Through handling of diseased and healthy plants
Tools (pruning shears)
Transporting contaminated soil on their feet/ equipment's
Contaminated container
Using infected seeds/ nursery stock.
By seeds and transplanting process
Transported to other fields
Are sold and transported to other areas
By human