Unit 3 Key Area 3 Flashcards
Why do weeds, pests, and diseases all have a negative impact on food production?
- Weeds compete with crop plants for natural resources
- pests and diseases cause damage to crop plants
Both of these reduce the productivity of the crop plants.
What are the different types of weeds?
- Annual weeds
- perennial weeds
What are some of the key properties of annual weeds?
- Rapid growth
- Short life cycle
- High seed output
- Long term seed viability (the seeds are able to stay alive for long periods of time)
What are some of the properties of perennial weeds?
- Storage organs
- vegetative reproduction
What are the different ways of controlling weeds, pests and diseases by cultural methods?
- Ploughing
- weeding
- Crop rotation (changing the times of year at which you grow certain crops)
What are the different types of pesticides/herbicides?
- Selective pesticides
- Systemic pesticides
(when we say pesticides in this context this also includes herbicides)
In what situation might we use selective herbicides?
Selective herbicides have a greater effect on certain kinds of plants such as in killing broad leaved weeds
What does a systemic herbicide do?
A systemic herbicide will spread through the vascular system of the weed and prevent regrowth
What do systemic pesticides do?
Systemic pesticides spread through the vascular system of the plant killing any pests that feed on the plant
What are some of the problems with using pesticides?
- pesticides have toxicity to non-target species
- pesticides bioaccumulate and biomagnify in food chains this causes damage to the ecosystem
- excessive use of pesticides can cause a population of pesticide resistant pests to develop
What is bioaccumulation?
Bioaccumulation is the build up of a chemical in an organism
What is biomagnification?
The increase in the concentration of a chemical between trophic levels of a food chain
Describe the process of biological control?
In biological control the control agent is a natural predator, pathogen, or parasite to the pest species.
What is meant by integrated pest management?
Integrated pest management is a combination of chemical, biological, and cultural control. (a balance of all three methods of reducing pests)