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Plant Disease Types and Symptoms

Plant Disease Types and Symptoms - e Parasitic Plants –...

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Pathology 9/2/10 1. Parasitic Plants a. Depend on other plants for nutrients b. Lack chlorophyll so no photosynthesis c. Some lack roots and so obtain water from other plants d. Have structures that allow penetration of host tissues e. Most serious- witch weed i. Small plant with red or yellow flowers 1. Attacks corn, sugar cane, rice, tobacco, cowpeas in Africa, asia, and Australia 2. Causes plants to wilt and die prematurely a. Losses can be up to 100% 2. Inoculum – any pathogen part or stage capable of initiating infection a. Fungi – mycelia, spores i. Some survive for hours while others for years ii. Some can swim iii. Sources: air, water, soil, insects, animals, seeds/planting material b. Bacteria – bacterial cells (can swim), spores (Gram positive) i. Sources: air, water, insects, seeds/planting material, animals c. Viruses – virus particles i. Sources: insects, seeds/planting materials ,soil, bacteria, fungi, nematodes d. Nematodes – eggs and juvenile stages
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i. Sources: soil, water, seeds/planting material
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Unformatted text preview: e. Parasitic Plants – seeds i. Sources: soil f. Biotroph: Obligate parasite (needs host alive) g. Necrotroph: Kills host 3. How pathogens cause disease a. Toxins (necrotrophic) – poisonous compounds produced by fungi and bacteria i. Toxins may produce disease symptoms 1. Active in low concentrations 2. Kill plant cells and allow pathogens to feed b. Growth regulators (biotrophic)– compounds that regulate plant growth patterns i. Pathogens may produce hormones that stimulate or retard plant growth c. Plant disease suppressors – compounds that suppress plant defense mechanisms d. Proliferation – multiplication in host tissues disrupt normal cell function 4. Symptoms of Plant Diseases a. Necrosis – collapse and death of plant cells leaving lesions/cankers/blights/etc. b. Hyperplasia/Hypertrophy – Overgrowths of tissue c. Hypoplasia/Hypotrophy – Undergrowth of tissue...
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Plant Disease Types and Symptoms - e Parasitic Plants –...

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