1 Plant Health Care Bacteria, Virus, Photoplasma


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1 Plant Health Care Bacteria, Virus, Photoplasma

  1. 1. Plant Health Care Bacteria, Virus and minor Pathogens
  2. 2.                                                                                            
  3. 3. Plant Diseases Causes of Plant Diseases <ul><li>Fungi </li></ul><ul><li>Bacteria </li></ul><ul><li>Viruses </li></ul><ul><li>Nematodes </li></ul><ul><li>Phytoplasma </li></ul><ul><li>Abiotic Factors </li></ul>
  4. 4. Causes of Plant Diseases <ul><li>BIOTIC and ABIOTIC . </li></ul><ul><li>BIOTIC causes of plant diseases are those that are biological in origin. There are five major biotic causes of plant diseases. These are the fungi, bacteria, viruses, nematodes and phytoplasmas. </li></ul>
  5. 5. Abiotic Causes <ul><li>ABIOTIC causes of plant diseases are non-biological in origin. Examples include things like adverse weather conditions or environmental pollutants. Often the affects of abiotic factors on plants are referred to as INJURIES . </li></ul>
  6. 6. Fungi <ul><li>Largest pathogen group </li></ul><ul><li>More than 8000 pathogenic species </li></ul><ul><li>Can be seen with the naked eye </li></ul><ul><li>Vegetative growth through production of multicellular fungal threads (hyphae) </li></ul><ul><li>Reproduce via spores </li></ul>
  7. 7. Bacteria <ul><li>About 200 pathogenic species </li></ul><ul><li>Can be seen with a light microscope </li></ul><ul><li>Simple, unicellular </li></ul><ul><li>Reproduce b binary fission </li></ul>
  8. 8. Identification <ul><li>Bacterial diseases are virtually impossible to identify definitively based on symptoms </li></ul><ul><li>Typically, in order to identify bacterial pathogens, the bacterium must be isolated from diseased tissue and then grown on specialized media. </li></ul>
  9. 9. Bacterial cells <ul><li>Bacterial cells are extremely small (see arrow). </li></ul><ul><li>Even when magnified to 400 times their normal size (as they are in this photo) they are difficult to distinguish as individual objects </li></ul><ul><li>Often one must stain the cells (as in this photo) to see them. </li></ul>
  10. 10. Symptoms <ul><li>SPOT symptoms </li></ul><ul><li>Often spots produced by bacteria have a water-soaked appearance and a well-defined yellow halo </li></ul><ul><li>However, be cautious when attempting to distinguish bacterial and fungal spots </li></ul><ul><li>Spots produced by bacteria and fungi are typically very similar </li></ul>
  11. 11. <ul><li>Bacterial lesions are often delimited (bordered) by veins (see arrow) and thus often have an angular appearance </li></ul>http://www.plantpath.wisc.edu/PDDCEducation/MasterGardener/General/Slide30.htm
  12. 12. Signs - Bacterial Streaming <ul><li>Cut the lesion from the leaf and place it on a microscope slide in a drop of water </li></ul><ul><li>Slice through the lesion with a razor blade </li></ul><ul><li>If bacteria are present they will &quot;stream&quot; out from the cut edges of the lesion </li></ul>
  13. 13. Bacteria <ul><li>Bacterial leaf spot </li></ul><ul><li>Bacterial Soft rot </li></ul><ul><li>Bacterial Wilt </li></ul><ul><li>Crown Gall </li></ul><ul><li>Fireblight </li></ul><ul><li>Slime Flux </li></ul>
  14. 14. Bacterial Leaf Spot <ul><li>Round, angular or elongated discoloration </li></ul><ul><li>May cover the entire leaf </li></ul><ul><li>Usually brown, may be surrounded by a yellow halo </li></ul><ul><li>Dead tissue drops out of leaves </li></ul><ul><li>Can affect fruit – sunken spots </li></ul>
  15. 15. Bacterial Leaf Spot
  16. 16. Bacterial Leaf Spot <ul><li>Affects many woody and herbaceous plants </li></ul><ul><li>Life cycle </li></ul><ul><ul><li>Overwinter in infected plant parts and seeds </li></ul></ul><ul><ul><li>Soil borne </li></ul></ul><ul><ul><li>Spread by contaminated tools and pots </li></ul></ul><ul><li>Prevention </li></ul><ul><ul><li>Sanitation, resistant cultivars, remove & destroy </li></ul></ul>
  17. 17. Bacterial Soft Rot Erwinia carotovora
  18. 18. Bacterial Soft Rot <ul><li>Fruit or storage roots </li></ul><ul><li>Water soaked, then soft, watery, and slimy gray or brown </li></ul><ul><li>May have a foul odor </li></ul>
  19. 19. Bacterial Soft Rot <ul><li>Above ground – yellow, stunted and wilted </li></ul><ul><li>Affects – wide range, fleshy fruits and succulent stems especially </li></ul><ul><li>Enters through wounds </li></ul><ul><li>Need high moisture – so store in cool, dry place </li></ul><ul><li>Rotate crops </li></ul>
  20. 20. Bacterial Wilt
  21. 21. Bacterial Wilt <ul><li>Interveinal chlorosis (yellowing), with the main leaf veins remaining dark green in color </li></ul>
  22. 22. Bacterial Wilt <ul><li>Wilt, at first parts soft then hard and dry </li></ul><ul><li>May see strands of long white ooze </li></ul><ul><li>Affects curcubit family & tomatoes & beans </li></ul><ul><li>Plant resistant cultivars </li></ul><ul><li>Use disease free seed </li></ul><ul><li>Remove & destroy affected plants </li></ul>
  23. 23. <ul><li>These stands are composed of plant sap and bacterial cells, held together by a sticky substance (called LPS) that is produced by and serves as a protective coat for the bacterium. </li></ul>
  24. 25. Crown Gall Agrobacterium <ul><li>The interior of a gall due to crown gall will have a mass of disorganized vascular tissue. </li></ul><ul><li>Lives in the soil and infects plants through wounds. </li></ul>
  25. 26. Crown Gall <ul><li>Populus, Salix, Prunus & Rose families </li></ul><ul><li>May form above ground on stems or branches or below ground on roots </li></ul><ul><li>Apple roots Euonymous stems </li></ul>
  26. 28. Crown Gall <ul><li>Above ground appears yellow and stunted </li></ul><ul><li>Enters through wounds or contaminated tools </li></ul><ul><li>Can survive on dead plants for years </li></ul><ul><li>Remove and destroy affected plants </li></ul><ul><li>Don’t replant in same place </li></ul>
  27. 29. Fire Blight <ul><li>Affects many in the Rose family: </li></ul><ul><li>crabapple, pear and apple trees </li></ul>
  28. 30. Fire Blight <ul><li>Flowers first – wilt, shrivel and turn brown </li></ul><ul><li>Leaves turn brown or black </li></ul><ul><li>Dead leaves remain on twigs </li></ul><ul><li>Shoot tips turn black, wilt and curl downward </li></ul><ul><li>Cancers on branches </li></ul><ul><li>Fruit black and may stay on the tree </li></ul>
  29. 31. Fire blight
  30. 32. Fire blight <ul><li>In spring, bacteria from previous year's cankers on twigs, branches and limbs are rain-splashed, wind-blown or carried by insects to blossoms </li></ul><ul><li>Plant resistant cultivars </li></ul><ul><li>Don’t prune too heavily encouraging succulent, susceptible tissue </li></ul><ul><li>Prune out affected tissue with 6-12” of healthy tissue </li></ul>
  31. 33. Fire Blight <ul><li>Advances from twigs to older branches and limbs causing localized cankers, which appear sunken, dark and wrinkled </li></ul><ul><li>Cankers on large scaffold limbs and the trunk eventually become cracked or creviced. </li></ul>
  32. 34. Slime Flux – Bacterial Wetwood <ul><li>The ooze often is foul-smelling, slimy, and colonized by yeast organisms when exposed to air </li></ul><ul><li>When the slime dries, it leaves a light gray to white crust on the bark </li></ul>
  33. 35. White foam oozing- Slime Flux <ul><li>yellow-brown discoloration confined to the central core of the tree </li></ul><ul><li>under high internal gas pressure </li></ul><ul><li>The gas pressure and high moisture content cause an oozing or bleeding of slime from wood and branch crotches </li></ul>
  34. 36. Bacterial ooze
  35. 37. <ul><li>Affects many woody plants </li></ul><ul><li>Elms, maples and poplars </li></ul><ul><li>Cosmetic damage </li></ul><ul><li>No control available </li></ul>
  36. 38. Viruses <ul><li>Can only be seen using an electron microscope </li></ul><ul><li>Extremely simple – nucleic acid with a protein coat </li></ul><ul><li>Reproduce by taking over host’ reproductive machinery </li></ul><ul><li>Often associated with insect vectors </li></ul>
  37. 39. Tulips with a virus
  38. 40. <ul><li>Virus symptoms </li></ul><ul><li>Leaf & fruit distortion </li></ul><ul><li>“ strappy” leaf, curled and twisted </li></ul><ul><li>Warty fruit </li></ul>
  39. 41. Virus <ul><li>Impatiens Necrotic Spot Virus (INSV) </li></ul><ul><li>Mosaic </li></ul><ul><li>Tomato Curly top Virus </li></ul><ul><li>Tomato Spotted Wilt Virus </li></ul>
  40. 42. Impatiens Necrotic Spot Virus <ul><li>Black stems </li></ul>
  41. 43. INSV <ul><li>Vectored by Thrips, variety of leaf symptoms. Not always rings </li></ul>
  42. 44. INSV <ul><li>Affects over 300 species, esp. bedding plants </li></ul><ul><li>Vectored by thrips </li></ul><ul><li>Use yellow sticky traps </li></ul><ul><li>Remove and destroy affected plants </li></ul><ul><li>INSV resistant cultivars </li></ul>
  43. 45. Mosaic
  44. 46. Mosaic <ul><li>Mottled leaves with yellow, white or streaked spots </li></ul><ul><li>Streaking or spotting on fruits </li></ul><ul><li>Often stunted growth </li></ul><ul><li>Affects a wide range of plants </li></ul><ul><li>Plant resistant cultivars </li></ul><ul><li>Spread by insects – esp. leafhoppers </li></ul>
  45. 47. Mosaic <ul><li>No control </li></ul><ul><li>Remove and destroy </li></ul>
  46. 48. Mosaic Watermelon
  47. 49. Tobacco Mosaic Virus
  48. 50. Tomato Curly Top Virus
  49. 51. Tomato Curly Top Virus <ul><li>Plants infected when older turn a dull yellow </li></ul><ul><li>Veins turn purple </li></ul><ul><li>Leaves roll upward, fruit production and ripening ceases </li></ul><ul><li>Plant slowly dies </li></ul><ul><li>Vectored by beet leafhoppers </li></ul>
  50. 52. Tomato Curly Top Virus
  51. 53. Tomato Curly Top Virus <ul><li>Affects – wide variety of herbaceous plants </li></ul><ul><li>Beets </li></ul><ul><li>Tomatoes </li></ul><ul><li>Beans </li></ul><ul><li>Melons </li></ul><ul><li>Remove and destroy </li></ul>
  52. 55. Tomato Spotted Wilt Virus <ul><li>splotches and yellow bulls-eye like rings on ripe tomato fruit </li></ul>
  53. 57. Phytoplasma <ul><li>Funky bacteria? </li></ul><ul><li>Small wall-less </li></ul><ul><li>Only in the phloem </li></ul><ul><li>Usually only see with an electron microscope </li></ul><ul><li>Reproduce by binary fission </li></ul><ul><li>Transmitted by insects (leafhoppers) </li></ul>
  54. 58. Phytoplasma <ul><li>Previously referred to as mycoplasma </li></ul><ul><li>Smaller than bacteria </li></ul><ul><li>No cell wall </li></ul><ul><li>Live in the phloem </li></ul><ul><li>Only seen with an electron microscope </li></ul><ul><li>Reproduce by splitting (as do bacteria) </li></ul>
  55. 59. Phytoplasma – Aster Yellows
  56. 60. Phytoplasma – Aster Yellows
  57. 61. <ul><li>Colored petals turn green </li></ul><ul><li>Brooming </li></ul>
  58. 62. Phytoplasma <ul><li>Yellow, stunted, strange growth patterns </li></ul><ul><li>Overwinters in affected tissue </li></ul><ul><li>Vectored by leaf hoppers </li></ul><ul><li>Remove and destroy affected plants </li></ul>
  59. 63. Phytoplasma – Carrots
  60. 64. Phytoplasma – Fasciation in Maple
  61. 65. Nematodes <ul><li>Parasitic worms </li></ul><ul><li>Very complex compared to other pathogens </li></ul><ul><li>Usually seen only with a light microscope </li></ul><ul><li>Reproduce by eggs </li></ul>
  62. 66. <ul><li>A stylet is a modified tooth that helps a nematode puncture and feed on plant tissue. </li></ul>
  63. 67. Root Knot Nematode
  64. 68. Root Knot Nematode <ul><li>Above ground – yellowed, wilted </li></ul><ul><li>Fruit stunted or non existent </li></ul><ul><li>Affects – fruit trees, corn, lettuce, tomatoes & potatoes </li></ul><ul><li>Plant resistant cultivars </li></ul><ul><li>Rotate crops </li></ul><ul><li>Soil solarization </li></ul><ul><li>Neem, organic matter </li></ul>
  65. 69. ID from Photographs Part I Bacteria
  66. 70. Bacterial Diseases <ul><li>Bacterial Leaf Spot </li></ul><ul><li>Bacterial Soft Rot </li></ul><ul><li>Bacterial Wilt </li></ul><ul><li>Fireblight </li></ul><ul><li>Bacterial Wetwood/Slime Flux </li></ul><ul><li>Crown Gall </li></ul>
  67. 77. Virus & Others <ul><li>Impatiens Necrotic Spot Virus (INSV) </li></ul><ul><li>Mosaic </li></ul><ul><li>Tomato Curly top Virus </li></ul><ul><li>Tomato Spotted Wilt Virus </li></ul><ul><li>Root Knot Nematode </li></ul><ul><li>Phytoplasma </li></ul><ul><li>Phytoplasma- fasciation </li></ul>