Plant Pathology David R. Drake

Pathology The study of disease. Disease Anything that causes abnormal growth

Plant Disease Any disturbance of a plant that interferes with its normal growth and development, economic value, and aesthetic quality; a continuously, often progressively affected condition in contrast to injury, which results from momentary damage. Source: Plant Diseases: Their Biology and Social Impact. Gail L. Schumann APS Press

Historical Plant Diseases Irish Potato Famine American Chestnut Blight Dutch Elm Disease. St. Anthony’s Fire Tulip Virus

St. Anthony’s Fire Ergot Prevalent in Rye

Tulip Virus Tulips introduced to Europe circa 1550 Virus infected bulbs created Tulipmania from

PRICE BARTERED FOR 1 BULB 4 Tons Wheat 8 Tons Rye 4 Fat Oxen 8 Fat Pigs 12 Fat Sheep 2 Hogsheads Wine 4 Barrels Beer 2 Barrels Butter 1000 Lbs Cheese 1 Bed with Accessories 1 Full-dress Suit 1 Silver Goblet

Types of Pathogens Parasitic Non-parasitic (abiotic)

Pathogen Host Environment Factors in Disease: Disease Triangle

Parasitic Fungi Bacteria Virus Nematodes protoplasma Parasitic plants

Fungi Lack cholorphyll 100,100 – beneficial Most microscopic Spores Fungicides

Bacteria Single-celled Binary fission Rapid multiplication Free moisture Bactericides

Virus Protein and nucleic acid Sub-microscopic Insect vectored Mechanical transmission

Nematodes Microscopic eel worms Eggs Stylet Virus vectors Nematicide

Protoplasma (mycoplasma) Similar to bacteria No cell wall Vectored by leafhoppers Controlled with antibiotics

Parasitic Plants

Dodder

Non-parasitic Iron chlorosis Powdery mildew Cytospora Fire blight

Iron Chlorosis

Powdery Mildew Halt (thiophanate methyl) Benlate Funginex Bayleton Sulfur Tilt

Funginex Roses – Powdery mildew – Rust (rare) Fruit – Powdery mildew – Brown rot (rare)

Cytospora Canker

Fire Blight

Fire Blight Control Avoid excess nitrogen Prune out cankers Treat with fixed copper or streptomycin

Cuitlachoche Safflower oil Onion chopped Garlic chopped Chilies Cuitalchoche 3T 2T Cups Saute’ until translucent

Verticillium Wilt

Chlorothalonil Disease control with Daconil Daconil lawn and garden fungicide Daconil 2787 Multi-purpose fungicide

White Mold

Slime Flux Wet Wood