Plant Diseases
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Transcript of Plant Diseases
Plant Diseases
• A disease is defined as any type of injurious abnormality
• A pathogen is any biological agent that causes an injurious abnormality
Plant diseases
• There are 4 types of commonly recognized pathogens– Virus– Bacteria– Fungi– nematodes
Signs and Symptoms
• Symptom is the plants response to attack by a pathogen
• Sign is structures produced by the organism ( spore producing structures, mycelium)
Virus
Tobacco Mosaic Virus
TMV
TMV
Virus symptoms
• Unthrifty plants– Slow to grow– Mosaic light spots and stripes
Aster YellowsActs like a virus but is a mycoplasma
Virus indexing
• If you are buying cloned plants they will often say Virus Indexed.
• That means they are tested and proven to be virus free.
• very important when buying raspberry plants or strawberry plants
Bacteria- fire blight
Fire Blight
Bacterial symptoms
• Rapid spread, can be spread by wind or insects,humans
• Soft rots producing snotty oooz
• Can be really smelly
Fungi
Botrytis – Grey Mold
Fungus
Fungus
• Signs: mycelium, fruiting bodies
• Symptoms: necrotic areas, wilt when fungus attacks the roots
• Phloem blockage, xylem blockage
Nematodes
• Root Knot Nematode
Nematodes
• Feed on roots and allow secondary infections
• Cause small tumors on roots
• Damage to plants by fungi bacteria and nematodes can be classified in 3 types– Direct damage by feeding– Toxins injected into the plant– From secondary infections that enter via the
physical damage caused by the primary agent
Crop infesting diseases are troublesome because they will continue to reproduce and feed
UNTIL
• 1. The food is used up
• 2. the environment becomes unfavorable
• 3. they are destroyed by some predator/ disease
Disease transmission
• Water is necessary for fungus infection
• Insects
• Humans
• Infected seed
• Infected soil – brought in on shoes or tractor tires
Curing or avoiding plant disease?
• Any of the previous factors can be interrupted• Cultural control
– Roguing, sanitation, plowing plant refuse under, stirring the soil to expose egg masses, keep plants healthy, avoid smoking, regulate pH, hot water treatment of seed,
• Chemical control
What are those letters?
• · V Verticillium Wilt Virus
• · F Fusarium Wilt Virus
• · N Nematodes
• · T, TMV, ToMV Tomato Mosaic Virus
• · BSK Bacterial Speck
• · ST Stemphyllium (Grey Leaf Spot)
• · FCR Fusarium Crown Rot