3D - Crop Protection Flashcards
How do weeds, affect crop plants?
Weeds compete directly with the crop plants for light, nutrients, water etc.
What type of pests largely affect crop plants?
Invertebrates animals such as insects, nematode worms and molluscs are the most common pests of crop plants.
What types of organisms cause most plant diseases?
Fungi, bacteria or viruses (which are often carried by invertebrates) cause most crop plant diseases.
Describe selective herbicides
Selective herbicides have a greater effect on certain plant species (broad leaved weeds)
Why are some fungicides sprayed prior to infection?
Fungicides are often applied based on disease forecasts as this is more effective than treating a crop after it is diseased.
What does biological control mean?
Biological control is where the control agent is a natural predator, parasite or pathogen of the pest. It is used to reduce the number of pests.
What are risks with using biological control?
With biological control risks that can occur if the control organism becomes an invasive species, or parasitise, prey on or be a pathogen of other species.
Describe the properties/competitive adaptations of annual and perennial weeds that make them ‘successful’ weeds?
Properties of annual weeds which make them good at competing include: rapid growth, short life cycles, high seed output and long-term seed viability.
Competitive adaptations of perennial weeds that make them successful include: storage organs and vegetative reproduction.
How can weeds, pests and diseases of crop plants be controlled?
Cultural methods such as ploughing, weeding and crop rotation can be used to control weeds/crops/diseases.
Chemical control includes: Herbicides to kill weeds Fungicides to control fungal diseases Insecticides to kill insect pests Molluscicides to kill mollusc pests Nematicides to kill nematode pests.
What are some problems with using pesticides?
Pesticides need to be used carefully since they can cause toxicity to non-target species, persistence in the environment, bioaccumulation or biomagnification in food chains or produce resistant populations of pests.
Why are field trials done?
Fields trials are carried out in a range of environments to compare the performance of different cultivars or treatments and to evaluate GM crops.
Describe systemic pesticides…
Systemic insecticides, molluscicides and nematicides spread through the vascular system of plants and then kill the pests that feed on the plants.
How do pests and diseases affect crop plants?
Pests and diseases damage plants directly and will all reduce the crop plant’s productivity (less photosynthesis since size of leaf likely reduced).
What is bioaccumulation?
Bioaccumulation is a build-up of a chemical in an organism.
What is biomagnification?
Biomagnification is an increase in the concentration of a chemical moving up between trophic levels.
