3.3.1 Detection & Identification of Plant Diseases

• Plant disease can be detected by:

  • Stunted growth.
  • Spots on leaves.
  • Areas of decay.
  • Growths.
  • Malformed stems or leaves.
  • Discolouration.
  • The presence of pests.
• Identification can be made by:

  • Reference to a gardening manual/website.
  • Taking infected plants to a laboratory to identify the pathogen.
  • Using testing kits that contain monoclonal antibodies.
• What can plants be infected by?

  Pathogens and insects.
• What is one virus that infects plants?

  Tobacco mosaic virus.
• What is one fungus that infects plants?

  Rose black spot.
• What is one insect that infects plants?

  Aphid.
• What can stunted growth be caused by?


  Nitrate deficiency.
• What can chlorosis be caused by?

  Magnesium deficiency.
• What do magnesium ions produce?

  Chlorophyll.
• What are nitrate ions necessary for?

  Protein synthesis and growth.
• The three main causes of plant diseases:

  1. Infection by microorganisms such as fungi, bacteria, or viruses.
  2. Attack by larger organisms, such as insects.
  3. Lack of essential minerals, such as nitrates, or magnesium ions.
• Why do plants require nitrates to make proteins?

  Nitrates contain the element nitrogen, which is essential for making amino acids. These amino acids can then be combined to make proteins.
• What is chlorosis?

  Yellowing of plant leaves due to a lack of chlorophyll.