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  1. 1. MAHADEV SHINDHE ID No:MA1TAE0135 Department of Plant Pathology COA, Shivamogga On Soil Health Paradigms and Implications for Disease Management Seminar
  2. 2. Introduction Definition Factors influencing soil health Management practices Case studies Conclussion
  3. 3. 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
  4. 4. Definitions Soil: An ecological system consisting of inorganic minerals, decomposing organic matter, living organisms and growing plants Soil: A farmer's "Silent Partner“
  5. 5. 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).
  6. 6. Properties healthy soil
  7. 7. 8
  8. 8. 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)
  9. 9. Soil Moisture Soil Temperature Soil pH Organic Matter Nutrients Beneficial Microorganisms Factors influencing soil health
  10. 10. Organic amendments Crop rotation Cover crops and Green manures Soil types Tillage practices Intercropping Factors influencing soil health
  11. 11. 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
  12. 12. Soil health and disease management Crop rotation Soil moisture, pH, temp Nutrient management Organic amendments Cover crops and green manures Beneficial organisms Conservation tillage
  13. 13. 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.
  14. 14. 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
  15. 15. 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.
  16. 16. 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)
  17. 17. 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
  18. 18. ORGANIC AMENDMENTS  Animal Manure  Green Manure (Crop Residues)  Composts  Peat  Blood Meal  Compost Tea  Fish Meal  Poultry Manure
  19. 19. 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
  20. 20. Pathogens: • Fusarium spp. • Phytophthora spp. • Pythium spp. • Rhizoctonia solani • Sclerotinia spp. • Sclerotium spp. • Thielaviopsis basicola • Verticillium dahliae
  21. 21. CROP ROTATION • Break disease cycle by reducing pathogen level • Alter the soil characteristics • Inhibition of pathogens by chemicals
  22. 22. 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
  23. 23. 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
  24. 24. COVER CROPS AND GREEN MANURES • Sudan grass-Meloidogyne hapla, Pratylenchus spp. • Hairy vetch-Thielaviopsis basicola Pythium spp. Rhizoctonia solani Fusarium spp.
  25. 25. 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
  26. 26. 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)
  27. 27. 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.
  28. 28. 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)
  29. 29. 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
  30. 30. Beneficial microorganisms
  31. 31. Nitrogen fixing bacteria  Rhizobium  Azotobacter  Azospirillum P solublising bacteria • Bacillus subtilis • Pseudomonas spp. Biofertilizers
  32. 32. 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.
  33. 33. Hyphae of the beneficial fungus Trichoderma wrap around the pathogenic fungus Rhizoctonia.
  34. 34. 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
  35. 35. 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.
  36. 36. CASE STUDIES
  37. 37. Objective: To know the effect of cropping sequences on Root Knot Nematode population
  38. 38. OBJECTIVE: The role of microbial activity in the effect of soil moisture and temperature on disease severity
  39. 39. Dry root weight of wheat seedlings with (a) and without (b) inoculation with R. solani AG-8, at different soil temperature and moisture levels.
  40. 40. Objective: To determine the effect of PMR amendments on soil borne and foliar diseases of cucumber and snap bean grown on a sandy soil
  41. 41. Objective: To evaluate the efficacy of Brassica cover crops used as soil amendments for managing Phytophthora blight of squash
  42. 42. 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).
  43. 43. Objective: to evaluate the effects of compost on bacterial wilt of potatoes
  44. 44. 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