Key Area 3.3 Flashcards
What is an advantage of a natural ecosystem
Genetic variety amongst species make them MORE RESILIENT to weeds, pests and diseases.
What is a monoculture
one species
genetically identical
very susceptible to weeds pests and diseases
What is the problems with monocultures?
ideal growing conditions for:
- weeds
- pests-
- disease causing micro-organisms
so control methods needed
Economical impacts of weeds?
- reduction in crop productivity (due to competition)
- reduction in crop growth (due to chemical inhibitors)
- cause disease (as they act as hosts for pests)
Name the types of weeds
Annual and Perennial
Give a definition and adaptations of annual weeds
Definition:
one year life cycle
Adaptions: •rapid growth •short life cycle •high seed output •long period of seed viability (seeds stay dormant until conditions are right)
Definition and adaptations of perennial weeds?
Definition:
Weeds all year round
Adaptations:
•storage organs for food in adverse conditions
•vegetative reproduction (runners and bulbs)
•competitive advantage because they are established before crops
Name and describe the types of pests
Nematodes -parasites in plant roots
e.g eel worms
Molluscs - eat leaves using rasping mouth parts which are ideal for touch plant materials
E.g snails/slugs
Insects - feed on plants using piercing or biting
E.g caterpillars
What kinds of microorganism causes diseases
Bacteria
Fungi
Viruses
Name the 3 types of controls for pests weeds and diseases
Cultural control
Chemical control
Biological control
What is the main purpose of cultural control
and
give examples of cultural control
Purpose?
To prevent
Examples:
Ploughing - first layer of soil flipped and weeds buried and die
Crop rotation: dissimilar plants planted in a cycle
Types of chemical controls
Herbicides
Pesticides
Fungicides
Types of herbicides
Selective
Systemic
Contact
How do selective herbicides work
Mimic growth hormones
Causes the broad leaf plant (weeds) metabolism to speed up until they exhaust their food resource and die
Narrow leaf plants (crops) absorb little of the herbicide and are not affected
What is an advantage and disadvantage of selective herbicides
Advantage: Biodegradable so do not chase harm to soil communities
Disadvantage: residue that may enter food chains
How do contact herbicides work
Kill green plant tissue they come into contact with
Advantage and disadvantage of contact herbicides
Advantage: biodegrade and short lived
Disadvantage: roots survive so weed can regrow
How do systemic herbicides work
Absorbed by the plant and transported to all areas of the plant
Advantage and disadvantage of systemic herbicides
Advantage:
attacks vascular system of the weed and totally destroy a it, stopping it from growing back
Disadvantage:
Slower acting
Name the types of pesticides
Contact
Systemic
Describe contact pesticides
Kills the pest when it comes into contact with it either through:
- spray
- layer of posing us residue (on crop)
Describe systemic pesticides
Absorbed by the plant and transported to all parts of the plant
When a pest eats the plant it intakes position as well as sap and dies
Name the types of fungicides
Contact
Systemic
Describe contact fungicides
Sprayed into crops
When fungal spores land and begin to grow they absorb poison and die
