crop protection 3

• Weeds


  Compete with crop plants, reducing productivity
• Pests and diseases


  Damage crop plants, reducing productivity
• Annual weeds


  • Rapid growth, short life cycle, high seed output, long-term seed viability
• Annual weeds


  • Annual Nettle
• Perennial weeds


  • Contain underground storage organs, use vegetative reproduction
• Perennial weeds


  • Dandelion
• Pests of crop plants


  • Invertebrate animals such as insects, nematode worms, molluscs (slugs)
• Plant diseases


  Can be caused by fungi, bacteria or viruses, often carried by invertebrates
• Cultural methods in controlling weeds, pests and diseases


  • Ploughing
  • Weeding
  • Crop rotation
• Ploughing


  Turning the topsoil by about 20cm to uproot underground storage organs
• Weeding


  Simple pulling out of any weeds
• Crop rotation


  Not planting the same crop in the same field every year to reduce build-up of disease or pests
• Selective herbicides


  Have a greater effect on certain plant species (broad leaved plants), only kill a particular type of weed
• Systemic


  Travels into the vascular system of the plant
• Systemic herbicides


  Spreads through the vascular system of the plant including the underground storage organs and prevents regrowth
• Systemic insecticides, molluscicide and nematicide

  Spreads through the vascular system of plants and kills pests feeding on plants
• Problems associated with pesticides


  • Toxicity to non-target species
  • Persistence in the environment
  • Bioaccumulation or biomagnification in food chains producing resistance pests
• Bioaccumulation


  Build-up of a chemical in an organism
• Biomagnification


  Increase in the concentration of a chemical moving between trophic levels
• Biological control


  The control agent is a natural predator, parasite or pathogen of the pest
• Integrated pest management


  Uses a combination of biological control, cultural and chemical methods to control pests and diseases
• The control organism may become an invasive species, parasite, prey on or be a pathogen of other species other than the pest