Flashcards in Key Area 3-Crop Protection Deck (24):
What are factors that can reduce a crop’s yield?
-competition from weeds
How do factors reduce yield?
What are annual weeds?
Weeds that complete their entire lifecycle in one year
Give four features of annual weeds
-short life cycle
-large quantities of seeds are produced
-seeds are viable for a long period of time
What are perennial weeds?
Plants that live for several years, becoming dormant in winter and growing again in the spring
Give two features of perennial weeds
They have storage organs for food for environments that don’t favour growth
They reproduce asexually using methods like runners: leads to rapid reproduction
What are pests?
Thy damage plants, usually invertebrates
What are the three groups of pests?
Nemotide worms: in the soil and attack the plants roots
Molluscs: snails/slugs destroy crops by eating leaves
Insects: damage plants by feeding on them
Mainly carried by invertebrates
What are three methods of control for weeds, pests and diseases?
What is cultural control?
Using traditional farming methods to protect plants
What are two methods of cultural control?
Ploughing-too layer of soil is turned over causing perennial weeds to be removed and buried, and decompose
Crop rotation-crops grown in a cycle in a field to break life cycle of pests specific to one crop
What are herbicides, pesticides and fungicides?
Chemicals sprayed to kill weeds(herbicides), pests(pesticides) and prevent growth of fungus(fungicides)
Describe the two types of herbicides and an advantage of each
Selective: only effect broad leaves plants~doesn’t affect any crops
Systemic: absorbed into transport system of plant~prevents regrowth of the weed
Describe the two types of pesticide
Contact: kill pests on the leave at time of spraying
Systemic: absorbed by the root and transported through the plant so any pests who tries to feed from the plant will be poisoned
Describe the two types of fungicides
Contact: prevents new fungus growth
Systemic: absorbed by the roots and transported through the plant to protect all part of the plant
Why are disease forecasts used when spraying fungicides?
Disease forecasts allow you to judge when to spray the fungicide based from when the optimal conditions are
What are four problems associated with plant protection chemicals?
-may be toxic to animal species
-can be persistent
-can accumulate in food chains
-can create resistant populations
What does pesticide resistance mean?
Chemicals in the pesticide do not break down and remain in the environment for a long period of time
What does magnification of pesticides in the food chain mean?
Organisms higher up the food chain consume more biomass and contain more fat so are found to contain more toxins
What does selection pressure mean?
When pesticides are sprayed onto a field it creates a selection pressure so only pests who are resistant to pesticides survive
What is biological control?
When a predator species is introduced to eradicate pest species
What are the risks of biological control?
Timing is crucial: if the species isn’t released at the time when the pest species is active it will be less effective
Controlled environment: species can escape if not released contained therefore controlled environments are better as the predator can not escape and conditions can be maintained as optimum