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

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

3. Host Environment Time Pathogen Disease DISEASE TRIANGLE

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

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

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

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

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

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

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

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

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

13. Coppers Controls some fungi and Fireblight Controls some fungi and Fireblight Free Cu - Copper sulfate: Bordeaux mixture Free Cu - Copper sulfate: Bordeaux mixture Fixed Cu - copper hydroxide, copper oxide, copper oxychloride, copper octanoate Fixed Cu - copper hydroxide, copper oxide, copper oxychloride, copper octanoate Kocides – restricted use, requires license Kocides – restricted use, requires license Safer Garden fungicide – Cu 12% or 0.4% : rust, scab, brown spot, black spot, others 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 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 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 Lilly Miller Cueva Cu soap – Cu octanoate 0.08%: PM, DM, gray mold, blight, spots Many other brands Many other brands

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

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

19. Antagonists/ Competitors Trichoderma harzium is the most researched Trichoderma harzium is the most researched Many others are being looked at Many others are being looked at

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

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

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