Plant diseases + defences

• Plants need mineral ions from the soil if there aren't enough plants suffer deficiency symptoms
• Plants need nitrates to make proteins for growth
• Magnesium ions are needed for for making chlorophyll which is needed for photosynthesis. Plants with a magnesium deficiency suffer from chlorosis and have yellow leaves.
• Common signs of a diseased plant are

  • stunted growth
  • patches of rot/decay
  • dicolouration
  • spots on leaves
  • malformed stems or leaves
• Identifying different plant diseases

  • Looking up signs in gardening manual
  • Using testing kits that identify the pathogen using monoclonal antibodies
• Plants have physical, chemical and mechanical defences
• Physical plant defences

  • waxy cuticle which provides a barrier to stop pathogen entry
  • cell walls made from cellulose act as barrier
• Chemical plant defences

  • produce antibacterial chemicals which kill bacteria
  • production of poisons
• Mechanical plant defences

  • thorns
  • leaves which droop or curl when touched
  • mimicry of other organisms