Plant disease

• What are the common signs of plant disease?


  • Stunted growth - nitrate deficiency
  • Spots - rose black spot
  • Areas of decay - rose black spot, potato blight
  • Abnormal growths - bacterial infection
  • Malformed stems or leaves - aphid infestation
  • Discolouration - magnesium deficiency or TMV
  • Pests
• How may we identify plant diseases?


  • Gardening manual / website
  • Send to a laboratory
  • Monoclonal antibody testing kits
• How may a magnesium deficiency cause chlorosis?


  • Magnesium is needed to make chlorophyll
  • Chlorophyll is needed for photosynthesis
  • Leaves become yellow and green
• What are the types of plant defences?


  • Physical
  • Chemical
  • Mechanical
• What are examples of physical defences in plants?


  • Waxy cuticle
  • Cellulose cell walls