Transcript Organic Approaches to Disease Control

Organic Approaches to
Disease Control
George Driever
Area Pest Management Specialist
Cooperative Extension Service
Oklahoma State University
Plant pathogens
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Fungi
Bacteria
Viruses
Phytoplasms
Nematodes
DISEASE TRIANGLE
Environment
Disease
Time
Pathogen
Host
Identifying Diseases by Symptoms
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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
Difficulties in Identification
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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
Methods of Disease Control
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Cultural
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Chemical
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Biological
Cultural Disease Control
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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
Cultural Disease Control cont’d
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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
Exclusion of Disease
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Certified disease free plants
Prevent introduction of diseased plants or soil
Disease free water source
Control insects that can carry disease
Soil solarization
Chemical Controls
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Hydrated Lime
Lime sulfur
Coppers
Horticultural Oils
Essential Oils
Bicarbonates
Antibiotics
Hydrated Lime
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pH adjustment
Component of Bordeaux mixture
Lime Sulphur
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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
Coppers
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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
Copper
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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
Horticultural oils
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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%
Essential Oils
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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
Bicarbonates
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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 ?
Antibiotics
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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
Antagonists/ Competitors
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Trichoderma harzium is the most researched
Many others are being looked at
Biological Controls
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Bacillus subtillus
Seranade Garden Disease Control – control
and suppression
Streptomyces griseoviridis – Pythium,
Botrytis, Fusarium, Alternaria, Phomopsis,
slightly on Phytopthora, Rhizoctonia
Pythium oligandrum DV 74 – hyperparasite
in testing on many pathogenic fungi
Nematode Control
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Exclusion
Resistant varieties
Crop rotation
Cover crops
Grain Rye (Elbon rye) for root knot
Solarization
Take Home Message
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Plan
Keep records
Scout
Learn disease symptoms
Be proactive in control