FOR EXTRA INFORMATION CONTACT MAHADEV SHINDHE DEP PLANT PATHOLOGY UAHS SHIVMOGGA

2. MAHADEV SHINDHE
ID No:MA1TAE0135
Department of Plant Pathology
COA, Shivamogga
On
Soil Health Paradigms and Implications for
Disease Management
Seminar

3. Introduction
Definition
Factors influencing soil health
Management practices
Case studies
Conclussion

4. In one teaspoon of soil there are…
 Bacteria 100 million to 1 billion
 Fungi 6-9 ft fungal strands put end to end
 Protozoa Several thousand flagellates & amoeba
One to several hundred ciliates
 Nematodes 10 to 20 bacterial feeders and a few fungal feeders
 Arthropods Up to 100
 Earthworms 5 or more
Introduction

5. Definitions
Soil: An ecological system consisting of
inorganic minerals, decomposing organic
matter, living organisms and growing plants
Soil: A farmer's "Silent Partner“

6. SOIL HEALTH:
• Soil health is a capacity of the soil to function as a vital living
system to sustains biological productivity maintain
environmental quality and promote plant, animal, and human
health.
• “A healthy soil should be capable of supporting life processes
such as plant anchorage and nutrient supply, retain optimal
water and soil properties, support soil food webs, recycle
nutrients, maintain microbial diversity, remediate pollutants,
sequester heavy metals, and contribute to disease suppression”
(Wang and Hooks, 2010).

7. Properties healthy soil

8. 8

9. CHARACTERISTICS OF HEALTHY SOILS
 Sufficient supply of nutrients.
 High biological diversity
 Ability to maintain the integrity of nutrient cycling and energy flow
 Suppression of multiple pests and pathogens
 Ability to improve plant health
 Maintenance of water and air quality
 Good soil tilth
 Good internal drainage
 Low populations of parasites
 High populations of plant-health promoting Organisms
 Low weed pressure
 No toxic chemicals that harm plants
Wang and Hooks (2010)

10. Soil Moisture
Soil Temperature
Soil pH
Organic Matter
Nutrients
Beneficial Microorganisms
Factors influencing soil health

11. Organic amendments
Crop rotation
Cover crops and Green manures
Soil types
Tillage practices
Intercropping
Factors influencing soil health

12. Soil health management practices
Manage organic matter
Minimize disturbances
Diversify soil biota
Maintain soil cover
Crop rotation
Cover crops and green manures
Organic amendments
Conservation tillage

13. Soil health and disease management
Crop rotation
Soil moisture,
pH, temp
Nutrient
management
Organic
amendments
Cover crops
and green
manures
Beneficial
organisms
Conservation
tillage

14. Soil moistutre
 Pathak and Srivastava (2001) reported that, with increasing
soil moisture and decreasing soil temperature, decreases the
incidence of Rhizoctonia bataticola in sunflower
 Soil Moisture Increase
 Phytophthora spp.
 Rhizoctonia spp.
 Pythium spp.
 Soil Moisture Decrease
 Fusarium spp.
 Verticillium spp.
 Armillaria spp.

15. Soil pH
• It affects nutrient availability and microbial
activity.
• Most plants and microorganisms prefer a pH
range of 6-7.
• Raising the soil pH to 6.5–7 by using nitrate
nitrogen in place of Ammonical nitrogen will
decrease the development of Fusarium wilt

16. Potato scab is more severe in soils with pH levels above 5.2.
Below 5.2 the disease is generally suppressed.
Club root of crucifers can be reduced by raising pH(alkaline)
Fusarium wilt disease (i.e. the more acidic the soil, the more
severe the disease).
Takeall of wheat disease- Gaeumannomyces graminis, is
favored by alkaline pH.

17. Soil pH have a strong effect on infective juveniles
survival.
Survival and pathogenicity nematodes declined slightly
as the soil pH decreased from pH 8 to pH 4.
Acidic soil with pH levels below 4.0 may limit the
nematodes host-finding
(Kung et al., 1990)

18. SOIL TEMPERATURE
Warm, moist soils with high levels of carbon to nitrogen will
have higher levels of microbial activity and a relatively higher
level of suppression
Most of the soil organisms function best at an optimum soil
temperature of 25 to 35⁰C
Soil temperature can greatly affect the activity of locomotion,
infection and reproduction of nematodes
High temperature can manage- Verticillium spp.
Decreasing soil temperature, decreases the incidence of
Rhizoctonia bataticola

19. ORGANIC AMENDMENTS
 Animal Manure
 Green Manure (Crop Residues)
 Composts
 Peat
 Blood Meal
 Compost Tea
 Fish Meal
 Poultry Manure

20. How does compost suppress
disease?
Improves soil physical and chemical properties
 Improve soil structure and fertility
 Enhanced activities of antagonistic microbes
 Increased competition against pathogens for resources that
cause fungistasis
 Release of fungitoxic compounds during organic matter
decomposition
 Induction of systemic resistance in the host plants

21. Pathogens:
• Fusarium spp.
• Phytophthora spp.
• Pythium spp.
• Rhizoctonia solani
• Sclerotinia spp.
• Sclerotium spp.
• Thielaviopsis basicola
• Verticillium dahliae

22. CROP ROTATION
• Break disease cycle by
reducing pathogen level
• Alter the soil
characteristics
• Inhibition of pathogens by
chemicals

23. BENIFICAL CROPS PATHOGEN REDUCED PRECEDING CROP (host)
Rice Verticillium dahliae Cotton
Peas Gaeumannomyces graminis Wheat
Maize , Wheat,
Sorghum
Ralstonia solanacearum Tomato and potato
Legume crops Streptomyces scabis Potato
Ground nut Meloidogyne incognita Tomato
Wheat Heterodera schachtii Sugarbeet
cereals Xanthomonas campestris pv.
campestris
Cabbage
Effect of Rotation on Pathogens

24. Growing of cover crops:
 Reduce erosion
 Improves the physical condition of soil
 Increase organic matter
 Increase soil microbial diversity by enhancing the soil
microflora.
 Reduce plant diseases
Cover crops:
 Sudangrass, Rye, Rapeseed, Oat, Mustard and Buckwheat
COVER CROPS AND GREEN MANURES

25. COVER CROPS AND GREEN MANURES
• Sudan grass-Meloidogyne hapla,
Pratylenchus spp.
• Hairy vetch-Thielaviopsis basicola
Pythium spp.
Rhizoctonia solani
Fusarium spp.

26. Crops suitable for green manuring
 Dhaincha ( Sesbania aculeata),
 Sunhemp (Crotalaria juncea),
 Cowpea (Vigna sinensis),
 Pea (Pisum sativum),
 Berseem (Trifolium alexandrinum),
 Lucerne (Medicago sativa)
Sunhemp Cowpea
26
Dhaincha

27. CONSERVATION TILLAGE
• Reduced tillage systems accumulate OM and
increase the rate at which soil microfloral and
microfaunal decomposition progresses
• Soils with high levels of OM have been shown
to prevent common root rot of cereals
(Cochliobolus spp)

28. NUTRIENTs
 Plants suffering a nutrient stress will be more
susceptible to diseases, while adequate crop nutrition
makes plants more tolerant or resistant to disease.
 The nutrient status of the soil and the use of particular
fertilizers and amendments can have significant
impacts on the pathogen’s environment.
 Calcium, play a major role in the ability of the plant to
develop stronger cell walls and tissues.

29. How can mineral nutrition prevent plant disease?
Mineral nutrition can affect two primary
resistance mechanisms:
A) Formation of
mechanical
barrier (eg.
Thickness of cell
wall )
B ) Synthesis of natural
defence compounds
(eg: phytoalexins ,
antioxidants and
flavanoids)

30. Nutrient Suppressing
Disease
Crops
Calcium 1)Clubroot
2)Fusarial wilt
3)Damping off
1) Crucifiers
2) Tomato, Watermelon and
cotton.
3) Peanut, Soybean, Pepper,
Tomato, onion, Bean and
Wheat.
Nitrate Fusarium wilt Tomato, Celery and Carnation.
Sulfur Scab Potato
Potassium Verticillium wilt Cotton
Phosphate Fusarium wilt Cotton and Muskmelon
Copper (cu) G. graminis var
tritici
Erysiphe spp.
Alternaria spp.
Take all of wheat ,
Powdery mildew of wheat
Sunflower
(Kausadikar et al ., 2006)
NUTRIENTs in management of plant diseases

31. Beneficial microorganisms

32. Nitrogen fixing bacteria
 Rhizobium
 Azotobacter
 Azospirillum
P solublising bacteria
• Bacillus subtilis
• Pseudomonas spp.
Biofertilizers

33. Bio control agents
 T. harzianum, T. viride ,T. hamatum
 VAM fungi , Bacillus subtilis, Pseudomonas fluorescens
Pathogens:
 Pythium spp.
 Fusarium spp.
 Sclerotium rolfsii
 Rhizoctonia solani
 Macrophomina phaseolina
 Alternaria spp.
 Sclerotinia spp.
 Verticillium spp.

34. Hyphae of the
beneficial fungus
Trichoderma wrap
around the
pathogenic fungus
Rhizoctonia.

35. EFFICACY OF SOIL HEALTH MANAGEMENT PRACTICES FOR PLANT
DISEASE MANAGEMENT
Positive effects
Not sufficient to complete control
20 to 80 per cent reduces soil borne diseases
Foliar pathogens diseases
Examples
Rust and mildews

36. Cont...
• Rhizobacteria: Induced Resistance to foliar and
soil borne disease
• Compost amendments induce resistance through
activation of plant defense response
• Examples: Botrytis Rot, Anthracnose, Angular
Leaf spot.
• Additional control measures for foliar pathogens.

37. CASE STUDIES

38. Objective: To know the effect of cropping sequences
on Root Knot Nematode population

41. OBJECTIVE: The role of microbial activity in the effect
of soil moisture and temperature on disease severity

42. Dry root weight of wheat seedlings with (a) and without (b)
inoculation with R. solani AG-8, at different soil temperature and
moisture levels.

43. Objective: To determine the effect of PMR amendments
on soil borne and foliar diseases of cucumber and snap
bean grown on a sandy soil

46. Objective: To evaluate the efficacy of Brassica cover
crops used as soil amendments for managing
Phytophthora blight of squash

47. Reduction in Phytophthora blight on squash plants by soil amendments with
shoots (A) or roots (B) of cover crops under greenhouse conditions. Plant
tissues were used to amend infested soils at 1 or 2.5% (plant/soil, w/w).

49. Objective: to evaluate the effects of compost on bacterial
wilt of potatoes

51. CONCLUSION
 Management practices that promote soil health by improving
soil physical, chemical, and biological properties, resulting in
improved nutrition, enhanced yield and disease suppression
 Contribute to building active, diverse and potentially disease-
suppressive microbial communities and can provide the base
of a sustainable disease management program
 Biodiversity is important to make management strategies
reliable
 Use of soil health management practices can substantially
reduce soil borne disease problems, but cannot completely
eliminate them, may take time to develop, and should be used
in conjunction with other approaches to achieve sustainable
disease management