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Semelhante a Plant Disease Identification and Life Cycle
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Plant Disease Identification and Life Cycle
- 2. What is a Disease? • A disease is any interference with the plant’s ability to grow normally. • Therefore, a disease in a plant could be a lack of water, too much water, a deficiency in a plant nutrient, or damage by a insect. • It can also be caused by microscopic organisms such as fungi and bacteria.
- 3. Infectious Diseases Infectious diseases are diseases that can attack a plant and, after obtaining nutrients from the plant, multiply and spread to infect other plants. • Fungi • Bacteria • Viruses
- 6. Bacteria Bacteria are one of three main domains of life on earth, found in almost every possible habitat. A prokaryote is a unicellular organism that lacks a membrane‐bound nucleus or other organelles.
- 7. Bacteria • Three Growth Shapes: • Coccus (cocci) ‐ round • Bacillus (bacilli) ‐ rod shaped • Spirillus (spirilli) ‐ corkscrew shaped • Some of these may have 1 ‐ 2 flagella.
- 8. Bacteria • Reproduction • They multiply very rapidly. • ‘Binary Fission’
- 9. Bacterial Disease • Soft rots • Leaf spots • Wilts • Blights • Sudden severe damage to leaves, stems or flowers. • Galls • Outgrowth or swelling of unorganized plant cells. • Cankers • Lesion on a stem, swollen or sunken area, surrounded by live tissue.
- 10. Bacteria • How are bacterial disease introduced into plants? • Wounds • Lenticels • Stomata • How are bacterial diseases disseminated? • Wind • Water • Tools • Insects
- 11. Bacteria 1. Fireblight 2. Leaf Scorch 3. Crown Gall 4. Leaf Spot
- 12. Fire Blight Erwinia amylovora • Signs/Symptoms • Blossom Blight: infected blossoms wilt, turn dark brown. The bacteria move down the spur into the leaves. • Twig Blight: Twigs take on a torched look, similar to a shepard’s crook. • Fruit Blight: Fruit is watery and ooze out milky or amber colored sap.
- 13. Fire Blight Damage • Sporatic dieback of foliage. • Stunted and deformed growth. • Death! • Primarily attacks plants of the Rosaceae family. • Apple • Pear • Pyracantha • Toyon • Cotoneaster • Loquat
- 14. Fire Blight Control • Use resistant varieties. • Sanitation – cut out infected twigs and cankers at least 18” beyond the infected areas. • Insecticides to control spread. • Dormant spray, if applicable. • Bactericide through the bloom period
- 15. Crown Gall Agrobacterium tumefacens • Signs/Symptoms • Overgrowths on the trunk that vary in size from a pea to 50 lbs. • Caused by hyperplasia and hypertrophy of cells. • Not to be confused with insect galls. Hyperplasia: a large increase in the number of cells. Hypertrophy: cells are larger than normal.
- 16. Crown Gall • Life Cycle • Soil inhabitant • Enters through wounds • Multiplies rapidly • Damage • Often enters at unsanitary graft union • Disfiguring growth • Eventual death
- 17. Crown Gall Control • Start with clean nursery stock • Resistant varieties • Grafts should be well wrapped • Soil insecticides • Avoid lawnmower and weed whip damage
- 18. Oleander Leaf Scorch Xylella fastidiosa • Signs/Symptoms • Dieback of leaf tips. • Scorched, yellow/light brown/rusty colored leaves. • Individual branches or full sections of the plant may be affected. • Symptoms may mimic drought or salt burn.
- 19. Oleander Leaf Scorch • Life Cycle • The bacteria are introduced into the plant by the Glassy Winged Sharp Shooter. • The bacteria multiply and clog the xylem vessels.
- 20. Oleander Leaf Scorch Control • Once the bacteria has entered the plant, there is no cure. • Prune out infected portions, similar to Fireblight. • Monitor insect populations • Plant removal.
- 21. Bacterial Leaf Spot Xanthamonas hederae • Signs/Symptoms • Ooze on the stems. • Leaf spots that begin as light green areas and become water soaked. • Spots turn brown with red margins. • Leaf petioles turn black and shrivel. • Plants may become dwarfed.
- 22. Bacterial Leaf Spot • Life Cycle • Bacteria spreads through splashing water. • Enters leaves through wounds and stomata. • Disease is most active during hot, humid weather. • Damage • Unsightly foliage (often found on ivy)
- 23. Bacterial Leaf Spot Control • Dormant spray, if applicable. • Avoid overhead watering during times of heat and humidity. • Water early in the day. • Remove infected parts.
- 25. Fungi • Fungi are a separate kingdom because: • They have no chlorophyll. • Their cell walls do not contain cellulose. • They have different biochemical pathways than plants.
- 27. Fungi • Spore: a reproductive unit, characteristic of these organisms. Similar to a seed but does not have a preformed embryo. • Fruiting Body: a sexual or asexual structure that produces spores. • https://youtu.be/XuKjBIBBAL8
- 29. Fungi • Haustoria: a finger‐like projection sprouting off a hypha. • Intercellular: grows between the cells. • Endomycorrhiza • Intracellular: grows into the cells. • Ectomycorrhiza
- 30. Black Sooty Mold • Signs/Symptoms • Black mold on foliage. • Reduced vigor of the plant. • Leaf yellowing. • Small fruit. • Life Cycle • Not a true parasite; it lives on honeydew.
- 31. Black Sooty Mold • Damage • No direct damage to plant. • Indirect damage is due to reduced photosynthesis. • Stunted growth. • Looks nasty! • Control • Control sucking insect that is producing honeydew. • Control ants. • Prune out infected parts. • Hard spray of water/soapy water(?)
- 32. Powdery Mildew • Signs/Symptoms • White felt or powder on the top surface of leaves, bud, flowers or fruit. • Usually found on most tender growth. • Life Cycle • Overwinters as mycelial mats. • Spores carried by wind. • Disease flares up quickly in humid and mod. temps.
- 33. Powdery Mildew • Damage • Deformed buds. • Stunted growth. • Ugly! • Can destroy flowers or fruit. • Control • Avoid evening watering and keep water on the soil. • Use resistant varieties. • Provide plant with plenty of light and air circulation. • Hose off plants in the middle of the day. • Fungicides (Immunox, Sun Spray Oil, baking soda spray.
- 34. Rust • Signs/Symptoms • Orange>>Brown>>Black spore pustules on the underside of the leaf. • Yellowing of leaf tissues on the topside. • Life Cycle • Very unusual – requires at least two hosts. • These two hosts may be 1000’s of miles apart. • 2‐5 types of spores might be produced. • Prefer low temps. and moisture.
- 35. Rust • Damage • Ugly! Reduces value of the plant. • Stunted growth. • Attacks a wide variety of plants. • Control • Use resistant varieties, if possible. • Keep water off of the foliage. • Prune out infected parts, if feasible. • Eliminate alternate host. • Fungicides(Mancozeb, Safer 3‐in‐1 Fungicide, sulfur spray)
- 36. Damping Off (Seedling Disease) Pythium, Phythophthora, Rhizoctonia, Thelaeviopsis. • Signs/Symptoms • Seed decay. • Seedlings fall over at the soil line. Lower stem is soft and brown. Life Cycle Varies; may overwinter as sclerotia or chlamydospore. Favor cool, moist conditions and poorly drained soil. Attack where the cells are not lignified.
- 37. Damping Off Control • Sanitation; sterilize tools, pots, soil, growing areas. • Seed treatment. • Keep excess moisture out of seed beds. • Drench soils with a fungicide. (Aliette) • Water early in the day.
- 38. Damping Off
- 39. Stem and Root Rot • Signs/Symptoms • Below ground – rootlets softened or dead. • Above ground – Stunting, wilting, death. • Stem at the soil line is brown/black and shriveled. • Life Cycle • Overwinter as spores. • Favored by cool, moist conditions and poorly drained soils. • Attack the plant where the cells are not yet lignified. • Control • Same as Damping Off
- 40. Peach Leaf Curl Taphrina deformens • Signs/Symptoms • Thickened, curled leaves that turn yellow and red. • Stunting of the shoots. • Life Cycle • Spores over‐winter on the tree bark. • Spores become active in the spring and re‐infect the young leaves. • Asexual spores are produced and a second infection takes place.
- 41. Peach Leaf Curl • Damage • Reduced tree health. • Low quality fruit. • Early leaf drop leads to less carbohydrate buildup in the roots; leads to a slow start in the spring. • Control • Clean up leaves and mummies. • Fungicide in the late fall after leaf drop and early spring before leaf push. (Daconil, Bravo ‐ chlorothalonil) • Kop R Spray, Liqui Cop dormant sprays. (8% copper; add 1% hort. Oil) • Bordoil and Orthorix were removed from shelf in 2011.
- 42. Anthracnose Colletotrichum, Gleosporum, Gnomonia sp. • Signs/Symptoms • Drooping of new foliage. • Necrotic leaf spots. • Twig blight. • Witches Broom • Ooze on the branches.
- 43. Anthracnose • Life Cycle • Over‐winters as mycelia in fallen leaves and twig cankers. • Spores are produced and spread as new foliage appears in the spring. • Spores ooze out the underside of the veins and spread with splashing rain. • Plants affected: Sycamores and Chinese Elms, Oaks, Vegetables and Fruit. • Damage • Twigs die. • Older leaves will have irregular brown areas. • Possible defoliation. • Large branches may die with several years of infection.
- 44. Anthracnose Control • Clean up leaf litter. • Spray 3x with Zineb; once when tree is dormant, once at bud break, and once 7 days later. • Fertilize trees to stimulate growth.