Plant diseases and defences

• Symptoms of plant disease:

  • stunted growth
  • spots on leaves
  • patches of decay
  • abnormal growth
  • discolouration
• physical defences:

  • waxy cuticle
  • cell walls
  • layer of dead cells around stem
• mechanical defences:

  • thorns and hairs
  • leaves that droop and curl by touch
  • mimic other organisms
• chemical defences:

  • production of antibacterial chemicals
  • produce poisons that deter herbivores
• If a plant has stunted growth, it likely is lacking the mineral nitrate or magnesium ions
• nitrate ions are used to make proteins
• a magnesium ion deficiency will cause a lack of chloroplasts