Soil borne pathogen and their impact

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2. Dhiman Adhikary
Id Number: 17 P. Path JJ-02M

3. Presentation Topic
Soil Borne Pathogens and Their Impact on
Crop Production

4. Soil Borne Pathogen
•Soil borne pathogens are tiny organisms like bacteria,
viruses or fungi that infect plant roots, stems, and leaves
•Reduced plant growth, increased costs to the growers, and
potential damage to the environment
•After all it lost the yield production
•Soil is a reservoir of inoculums of these pathogens, the
majority of which are widely distributed in agricultural soils

5. Soil Borne Disease:
•The diseases that are caused by these pathogens which survive
in the soil and in residues on the soil surface are defined as soil
borne diseases.
•Cause many destructive crop diseases such as
# Damping-off, # Root rots, # Collar rots,
# Stem rot and # Wilt diseases
•Reduced plant growth, increased costs or significant economic
loss to the growers and potential damage to the environment.

6. Survival of the Soil Borne Pathogen
•Soil inhabitants (survive in soil for relatively longer periods),
soil invaders (survive in the soil for relatively shorter periods).
•Non-pathogenic and generally in the form of saprobes
(organisms that live on decaying organic matter).
•In crop debrisIn crop debris
•In seedIn seed
•On alternate hosts (including weeds)On alternate hosts (including weeds)

7. Types of Soil-borne Pathogens
•Fungus
Root rots
Stem, collar, and crown rots
Wilt diseases,
Damping off Diseases
•Bacteria
Erwinia (soft rot),
Rhizomonas (corky root of lettuce)
Streptomyces (potato scab, soft rot of Sweet potatos)
•Viruses
stunting and yellowing and spotting of lower leaves
•Nematodes
Root rot nematodes

8. Fungus diseases
Root rots
•Root system to begin to decay
•Include wilting, yellowing, stunting,
dieback and eventual death
•Pathogens infect the plant's roots and
block the uptake and flow of water and
nutrients through the plant.
Cylindrocladium, Pythium,
Phytophthora, and Rhizoctonia.

9. Stem, collar, and crown rots
•Affect the plant at ground level
•Symptoms are similar to root rots, but
since the rotting start above the soil
line, it can be easier to detect early.
Phytophthora, Rhizoctonia, Sclerotinia,
and Sclerotium.

10. Wilt diseases:
• wilting, chlorosis, necrosis,
•premature leaf drop,
•browning of the vascular system,
stunting
•cause wilting of the plants, despite
adequate water.
Fusarium oxysporum and Verticillium
spp.
Damping off disease
•affect young seedlings.
•infect the plants at germination or
shortly after, causing sudden death
Pythium, Phytophthora, Rhizoctonia and
Sclerotium rolfsii.

11. Erwinia (soft rot)
•watery and soft decay of the tissue
•change in color and in the case of a carrot
•stem also rots and becomes mushy with
its colorless
Root rot nematodes
•Stunted growth,
•yellowing leaves, thinning plants,
•damage in patches and premature wilting

12. Impact of soil borne pathogen on crop
Soil borne pathogen is very harmful for the crop production.
Most of the soil borne pathogen destroy the crop production.
•Reduce the yield
•Economic loss
•Severe stage plant can’t survive
Some soil borne pathogen is also beneficial for the crop
production.
•Some nitrogen fixing bacteria like Azotobactor, Rhizobium live
in the plant root and produce nodule and fixation nitrogen from
the air. This nitrogen is beneficial for the crop.

13. Management of Soil borne Pathogen
•Growers must first know what pathogens are present,
•Where they are prevalent, and
•Finally how much inoculums is in the soil
Soil borne pathogen can be manage by three ways
•Cultural Control
•Biological Control
•Chemical Control

14. Cultural Control
Fertilizer application:
•Ammonium bicarbonate reduce the viability of sclerotial bodies of S.
rolfsii
•Pythium and Phytophthora by application of phosphoric acid
•Rypsum reduces the incidence of Macrophominain groundnut
Providing good soil drainage and good air circulation among plants
•Good soil drainage reduces the number and activity of certain
oomycetes pathogens (eg.,Pythium) and nematodes.
•Flooding fields for long periods or dry fallowing may also
reduce Fusarium, Sclerotiniasclerotiorum, and nematodes

15. Crop Rotation
Rotation with legume and non-legume
Tillage practices
Deep ploughing of crop residues
Soil amendments
•organic amendments like saw dust, straw, oil cake, etc
•manage the diseases Pythium, Phytophthora, Macrophomina
Soil Solarization
•clear polyethylene is placed over moist soil during sunny summer
days
•increased soil temperature from solar heat

16. Biological control
•Biological control agents colonize the rizosphere, the site
requiring protection
•Flurescent psedudomonads are the most frequently used
bacteria for biological control and plant growth promotion
but Bacillus and Streptomyces species have also been
commonly used.

17. Chemical Control
•Fumigation, soil drenching and seed treatment
•Fungicides like prothiocarb, propamocarb and metalaxyl
are useful to control the soilborne pathogens
•Fungicides used for soil treatments include metalaxyl,
diazoben, pentachloronitrobenzene(PCNB), captan, and
chloroneb

18. Thanks
to All