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Organic Approaches to Disease Control

Organic Approaches to Disease Control. George Driever Area Pest Management Specialist Cooperative Extension Service Oklahoma State University. Plant pathogens. Fungi Bacteria Viruses Phytoplasms Nematodes. Environment. Disease. Time. Pathogen. Host. DISEASE TRIANGLE.

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Organic Approaches to Disease Control

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  1. Organic Approaches to Disease Control George Driever Area Pest Management Specialist Cooperative Extension Service Oklahoma State University

  2. Plant pathogens • Fungi • Bacteria • Viruses • Phytoplasms • Nematodes

  3. Environment Disease Time Pathogen Host DISEASE TRIANGLE

  4. Identifying Diseases by Symptoms • Fungi – spots, lesions, blights, yellowing of leaves, wilts, cankers, rots, fruiting bodies • Bacteria – water-soaking, spots, wilts, rots, blights, cankers, exudates, galls, yellowing • Viruses – mottling, leaf and stem distortions, stunting • Phytoplasms – similar to virus symptoms • Nematodes – stunting, dying plants

  5. Difficulties in Identification • Plant pathogens are very small • Similar symptoms between bacteria and fungi and between fungal groups • Field diagnosis is difficult • Multiple pathogens may be present at the same time. • Multiple symptoms may be present

  6. Methods of Disease Control • Cultural • Chemical • Biological

  7. Cultural Disease Control • Develop soil rich in organic matter • Plant on raised beds • Plant tolerant or resistant varieties • Crop rotation • Plants adapted to area • Plant at proper depth (below crown or graft) • Use only thoroughly composted material

  8. Cultural Disease Control cont’d • Soil pH adjustment • Improve air circulation by staking, trellis or pruning • Remove weeds: carry disease, circulation • Water in the morning • Avoid high angle sprinklers • Do not over fertilize • Remove diseased plants and destroy

  9. Exclusion of Disease • Certified disease free plants • Prevent introduction of diseased plants or soil • Disease free water source • Control insects that can carry disease • Soil solarization

  10. Chemical Controls • Hydrated Lime • Lime sulfur • Coppers • Horticultural Oils • Essential Oils • Bicarbonates • Antibiotics

  11. Hydrated Lime • pH adjustment • Component of Bordeaux mixture

  12. Lime Sulphur • Use as a protectant dust or spray to control some fungal or bacterial diseases • Helps control peach leaf curl, rust, powdery mildew (PM), brown rot • Lilly Miller Poly Sul Lime Sulfur – Calcium Polysulfide – 28.7% • Generic and other brands available

  13. Coppers • Controls some fungi and Fireblight • Free Cu - Copper sulfate: Bordeaux mixture • Fixed Cu - copper hydroxide, copper oxide, copper oxychloride, copper octanoate • Kocides – restricted use, requires license • Safer Garden fungicide – Cu 12% or 0.4% : rust, scab, brown spot, black spot, others

  14. Copper • Bonide Liquid Cu – Cu octanoate 0.08% : PM, rust, black spot, late blight, others • Bonide Copper Garden Dust – copper sulfate and rotenone for fruits, garden, and flowers • Lilly Miller Cueva Cu soap – Cu octanoate 0.08%: PM, DM, gray mold, blight, spots • Many other brands

  15. Horticultural oils • Mostly controls foliar insects, but also peach leaf curl, and some other fungi • Dormant, suffocating, summer oils • Fungus Pharm – soybean oil plus Rosemary oil 0.1%

  16. Essential Oils • Neem oil – up to 70%: many brands that control insects, mites and some fungi such as PM, rust, scab, leaf spots, anthracnose and black spot • Green Light Organic fungicide – Rosemary Oil 0.2%: anthracnose, blights, gray mold, PM, DM, leaf spots, scab, rusts, others

  17. Bicarbonates • Potassium Bicarbonate – disrupts cell membrane K balance Bi Carb - K bicarbonate: PM, others Safer 3 in 1 – K salts: PM Black spot, leaf spots, rusts for seed, transplants or established plants • Sodium Bicarbonate ?

  18. Antibiotics • Streptomycin sulfate – many brands for agricultural use to control bacteria, fireblight FertilomeFireblight spray : also for bacterial wilt, stem rot, leaf spots and crown gall • Tetracycline - fireblight

  19. Antagonists/ Competitors • Trichodermaharzium is the most researched • Many others are being looked at

  20. Biological Controls • Bacillus subtillus Seranade Garden Disease Control – control and suppression • Streptomycesgriseoviridis – Pythium, Botrytis, Fusarium, Alternaria, Phomopsis, slightly on Phytopthora, Rhizoctonia • Pythiumoligandrum DV 74 – hyperparasite in testing on many pathogenic fungi

  21. Nematode Control • Exclusion • Resistant varieties • Crop rotation • Cover crops Grain Rye (Elbon rye) for root knot • Solarization

  22. Take Home Message • Plan • Keep records • Scout • Learn disease symptoms • Be proactive in control

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