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@No tll bca and biofertilizers 2012 09 04 a

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Modern biocontrol

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@No tll bca and biofertilizers 2012 09 04 a

  1. 1. Modern Biocontrol Agents and Biofertilizers Prof. Mark Laing Plant Pathology, UKZN & Plant Health Products (Pty) Ltd
  2. 2. Infected Ant
  3. 3. The Future is Here, for BCAs 1. Fewer pesticides available 2. A wider range of BCAs 3. Better formulations, shelf-life, simplicity 4. Biofertilizers: • N fixing – nodules and free-living • Mobilization of P and micronutrients • Buffering abiotic stress: • Tolerance of heat, cold, drought, waterlogging, soil toxins, toxic metals 5. Soluble silicon - a powerful tool to add
  4. 4. Beneficial Microbes for Agriculture – available of coming soon ! 1. Biocontrol Agents to control • Diseases, pre- and post-harvest - most • Pests - most • Nematodes – coming now Added benefit – Growth stimulation esp. seed and roots 2. Biofertilizers to enhance fertilization • N fixation – Rhizobium, Azotobacter, etc. • P mobilization • Micronutrient mobilization – Mo, Bo, Zn, Fe
  5. 5. What growers need: Registered, commercial BCA products: effective, affordable, stable, simple
  6. 6. Field Crop Soil Problems • Seed death, damping off and uneven stand (sub-lethal infection) • Root diseases of adult plants – Cause - Pythium, Rhizoctonia, Fusarium spp., Ggt (take-all) – Solution - seed treat with Trichoderma (e.g., Eco-T from PHP) • It stimulates early germination • It colonizes the emerging root • It stimulates more lateral root formation • It kills incoming pathogens and nematodes • It degrades allelochemicals in the soil • It buffers versus abiotic stress factors
  7. 7. Biocontrol of Rhizoctonia on cucumber seedlings
  8. 8. Trichoderma coils, penetrates, kills. Enzymes digest cell walls and contents. Feeding like a spider on a fly. D T R B TP R C T C R A
  9. 9. 0 20 40 60 80 100 120Untreated Cruizeronly Eco-T onlyCruizer+ Eco-T TrichoPlus only Cruizer+ TrichoPlus avg.rootweight Effects of treatments on root wet weight A Maize Trial with 2 Trichodermas & Cruiser
  10. 10. Mechanisms of Biocontrol 1. Hyper-parasitism (eats fungus) 2. Antibiosis (chemicals that attack pathogens) 3. Competitive displacement (eats nutrients first) 4. Triggering resistance in host (SAR) 5. Binds iron needed by pathogen (releases binding agents, siderophores)
  11. 11. Kenyan Lisianthus with Fusarium oxysporum root rot No treatment Trichoderma applied weekly
  12. 12. Survival(%) 0 20 40 60 80 100 Control Rhizoc Tdr+ Rhizoc Tst+ Rhizoc Treatment Survival(%) TotalDryWeight 0 2 4 6 8 10 Control Rhizoc Tdr+ Rhizoc Tst+ Rhizoc Treatment DryWeight(g) Biocontrol of Rhizoctonia on cucumber seedlings
  13. 13. Foliar Diseases – 2 examples • Rust biocontrol– fungus Sphaerellopsis filum attacks pustules and stops carryover – isolate, screen, register. Studies on biology, epidemiology, efficacy over seasons, economics of its use, culture conditions. • Powdery mildew biocontrol - Ampelomyces quisqualis (AQ). AQ10 was commercialized previously. PHP has worked out its production but it needs registration trials.
  14. 14. A rust pustule colonized by S. filum S. filum – black spore capsules in the old rust pustule A new rust pustule
  15. 15. Infection of wheat rust spore by S. filum (Plachecka 2005) 17 Rust Spore Rust Spore
  16. 16. Ampelomyces quisqualis attacking grape powdery mildew, U. necator 18 A pycnidium of A. quisqualis developed inside a spore of pm, showing the powdery mildew colony on a grape leaf in the background. Photos - D. Gadoury Spores of A. quisqualis emerging from a pycnidium of A. quisqualis, formed in place of a pm conidium
  17. 17. Post-Harvest vs Moulds and Insects • Eco-77 – colonize flowers of wheat and maize to stop Aspergillus & Fusarium (source of mycotoxins) • Yeasts: e.g. YieldPlus, B13 • Control of weevils & moths (USDA too) – Beauveria bassiana – Bacillus thurungiensis
  18. 18. Untreated Control Yeast B13
  19. 19. Rice Weevil (Sitophilus oryzae) infected with Beauvaria bassiana Rice Weevil (Sitophilus oryzae) infected with Beauvaria bassiana
  20. 20. Insect Pests • Aphids – Conidiobolus ? • Caterpillars – Viruses, Btk, Bb • Bollworm - viruses • Red spider – Beauveria bassiana • Thrips – Bb • Beetles, weevils – Bb, EPNs • Whitegrubs – B. brognartia, Bb, Bt
  21. 21. Beauveria bassiana parasitizing army worm larvae
  22. 22. Beauveria-infected white grub adult Beauveria-infected black vine weevil
  23. 23. Dead red spider mites after Eco-Bb x K silicate on brinjal (Gatarahiya & Laing, 2008) 0 20 40 60 80 100 120 0 1 2 Beauveria rate (g l-1) %deadmites (adults+juveniles) No Si With Si
  24. 24. Bollworm on Wheat Infected by Virus
  25. 25. Beetle grub filled with EPN’s Pictures taken from the University of Florida extension service web-site http://edis.ifas.ufl.edu/IN468
  26. 26. Entomopathogenic nematode entering an insect larva EPN Larva
  27. 27. Nematode (Eelworm) Biocontrol • Trichoderma (Eco-T) is suppressive • Nematode trapping fungi – Clonostachys rosae eats nematode larvae • Bacillus thurungiensis strains kill if eaten • Bayer – Votivo = Bacillus firmus • Products that eat nematode eggs – to kill all eggs in top 300mm of soil, requires 2000 kg / ha vs recommended 2kg / ha • Rotate with a Brassica crop (e.g., canola, cabbage) – mustard gases released • Nematodes in sheep and goats !
  28. 28. Nematode attacked by a nematode- trapping fungus
  29. 29. 1. Eliminates sub-lethal pathogens 2. Plant hormones released 3. Mineralization – P, Mo dissolved 4. Detoxification – allellochemicals and metals 5. Environmental buffering Growth Stimulation by Trichoderma: Modes of action
  30. 30. No Treatment Trichoderma
  31. 31. Nutrient uptake can be enhanced by alterations to root structure Untreated 1.8 area units Eco-T seed treatment 3.2 area units
  32. 32. Eco-T treated maize root numerous root hairs Untreated maize root Few root hairs Nutrient uptake is enhanced by increased number of root hairs
  33. 33. Root and shoot lengths of perenial ryegrass (69 days) 0 50 100 150 200 250 Untreated Treated Untreated Treated Feb planting March planting Length(mm) Shoot Root
  34. 34. Abiotic Stress: some Trichoderma strains and beneficial soil bacteria buffer plants from extreme environmental conditions: • Waterlogging • Drought • pH extremes • Nutritional stress • Pathogen / Environment interaction
  35. 35. Eco-T® buffers vs water-logging
  36. 36. Effects of soil moisture in lettuce (inoculated with Pythium) 0 100 200 300 400 500 600 700 800Yield(g)wetweight uninoculated control inoculated control biocontrol Treatments optimum irrigationhalf double
  37. 37. 0 20 40 60 80 Meanwetweight(g) control(u) control(i) biocontrol Treatments 6C 12C 18C 24C 30C Effect of water temperature on biological interactions in hydroponic lettuce (inoculated with Pythium)
  38. 38. 40 60 80 100 120 140 160 Meantotalwetweights(g) control(u) control(i) biocontrol Treatments pH4 pH5 pH6 pH7 Effect of pH on disease severity and biocontrol activity
  39. 39. Formulations and Applications • Crucial to activity – eg Bb • Application must maximize BCA activity – e.g., Eco-T on seed vs drenching • Needs to be simple, accurate, affordable to attract farmers • Must not conflict with farmer operations • New approach for field crops – Eco-T in John Deere talc+graphite lubricant for planter bins
  40. 40. Biofertilizers • Symbiotic N fixation – only legumes – Rhizobium nodules – Promiscuous strains under development for other legumes – Room storage at 200C • Free Living N fixation – for all crops – Azotobacter, Azospirillum sp. – Burkholderia sp., Klebsiella • P access, dissolved from clay, rock phosphate – Bacillus spp. – Trichoderma – Mycorrhizae • Micronutrient access (Mo, Bo, Zn, Cu, Fe) – Trichoderma – Mycorrhizae
  41. 41. Soybean – Rhizobium nodules (Strain WB74) Red nodule = fixing N Green nodule = parasite !
  42. 42. Effect of microbial treatments on Soybean yield 0 500 1000 1500 2000 2500 untreated Eco-T 1x Eco-T 2x Rhizobium Eco-T + R hizobium Treatments Yield(g) Series1
  43. 43. Rhizobium vs waterlogging stress in wattle
  44. 44. • N fixation for all the other crops • Free-living diazotrophic bacteria to fix nitrogen in the root zone • How much NPK fertilizer can be replaced by the best Azotobacter strains ? • To date: 65% replacement of normal NPK fertilizer without affecting normal plant growth, using best strains • P solubilization by other bacteria
  45. 45. Figure Increased rooting in treated plants (left)
  46. 46. Soluble Silicon in Plant Health • Silicon deficient soils - >70% of Africa short of soluble Si • No deficiency symptoms but both physical and biochemical role in some plants (Si uptake is active) • Grasses deposit Si as phytoliths into leaves; cane cuts • Action vs Pests – accelerated resistance • Action vs Diseases – accelerated SAR (immune system) • Improves orderly cellulose deposition • Stress tolerance – Cold, frost – Heat – Drought – Al, Mn, Cd • Synergistic with biocontrol agents
  47. 47. Typical Opal Phytoliths (maize & grass)
  48. 48. Liang, Sun, Zhu, Christie 2006 • Silicon effectively mitigates abiotic stresses: – Manganese, aluminum and heavy metal toxicities – Salinity – Drought – Chilling and freezing stresses • Mechanisms poorly understood Abiotic Stress Buffering by Si
  49. 49. Cold Stress: bananas after 40C x 4 days
  50. 50. The Future of BCAs 1. Fewer pesticides available 2. A wider range of BCAs 3. Better formulations, shelf-life, simplicity 4. Biofertilizers: • N fixing – nodules and free-living • Mobilization of P and micronutrients • Buffering abiotic stress: • Tolerance of heat, cold, drought, waterlogging, soil toxins, toxic metals 5. Soluble silicon - a powerful tool to add
  51. 51. Potential Problems with BCA & BFZ • Foreign strains, not well adapted to SA soils • Many strains need to be screened to find one really powerful strain – requires time, money and research facilities • Good BCA but poor formulation = ineffective • Spores counts too low – 105 /g instead of 107 /g • Contamination by other fungi • It is not a chemical, but a living organism. Back seat of a car for 4 hours will kill it. • Relatively short-lived except spore-formers (Bacillus), 6-12 months
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