R2103 1.1 Explain what is meant by physical, cultural, chemical or biological control Flashcards
Two benefits of physical control
- Most methods once established remain for a long time e.g. fences, netting
- Usually need little maintenance e.g. plastic sheets
Benefits of cultural control
two required
- Generally environmentally friendly and free
- Can fit in with daily routines e.g. regular feeding of plants
- Long lasting effects e.g. removal of alternate host weed species such as sheppards purse
Two benefits of chemical control
- Produces rapid control
- Products are easily accessible
- Can target specific pests
Two benefits of biological control
- non-toxic to humans, wildlife and pets
- Number of predators and parasites increase naturally
- No build up of resistant pests and diseases
- A balance population of predators and parasites is reached
Limitations of physical control
Two required
- Barriers and traps and harm other species not just those designed to control
- Fleece, mesh, netting needs to be in place before damage occurs
- Fleece, mesh, netting can be expensive
- Fleece, mesh, netting can be non-biodegradable
- Physical controls can be labour intensive
- Squishing / picking off only occurs in your presence
- Netting can trap wildlife like hedgehogs
- Yellow sticky traps could also trap beneficial insects e.g. pollinators
Limitations of cultural control
2 required
- May be time consuming
- May lack rapid action as seen with pesticides
- More knowledge, planning and research required
- Selecting plants for disease resistance reduces choices of cultivars
- Quarantining plants keeps then in pots for longer
Two limitations of chemical control
- Products can be dangerous to humans, animals and plants
- Products can cause resistant strains of pests, diseases and weeds to develop
- Contimination of streams and dams
- Damage to cultivated and wild plants, especially by herbicides
- Can be expensive
- Chemical residues can persist on food crops
Two limitations of biological control
- Needs careful introduction and knowledge of life cycles
- Can be easily affected by pesticides
Examples of physical control
- Plastic sheet - weed supressing
- Fleece - prevent entry of pests
- Fences - deter rabbits and deer
- Beer traps for slugs
- Rodent traps
- Copper tape for slugs
- Sacrificial crops - e.g. row of lettuce between two rows of tomatoes
- Deterents - onions planted between carrots to deter carrot fly
- Sticky traps - yellow colour attracts many pests such as white fly
- Squishing / picking off pest e.g. lily beetles
Example of cultural control
- Crop rotation
- Using resistant plant varieties
- Good management and work practices
- Quarantining new plants to prevent the introduction of pests and disease
Example of chemical control
Botantical - Pyrethroids
Based on pyrethrum
Rapid paralysing action but relatively safe
Breaks down easily - storage problems
Example of biological control
- Indigenous e.g. Blue tits eating catapillars
- Exotic e.g. Wasp Encarsia formosa lays eggs in glasshouse whitefly
Minimise risks to people and environment: physical control
Ensure safe removal of infected trees
Ensure safe burning of infected plant material
Ensure all equipment is used correctly
Minimise risks to people and environment: cultural control
Check material does not contain pests or diseases
Minimise risks to people and environment: chemical control
- Only use when properly justified
- Choose least harmful chemical to control organism
- Read instructions on label
- Wear correct clothing
- Apply under dry, wind free conditions
- Carefully store in secure, safe, dry place away from children and pets
Minimise risks to people and environment: biological control
- Unsuccessful appliation of biological control organisms can lead to a severe pest problem
- Incorrect introduction of a biological control can kill desirable organisms
- Choose best predator or parasite for the problem pest of disease concerned
- Understand both the pests and predator / parasites life cycles in order to achieve reliable control
What is physical control?
Physical or mechanical control methods involve using barriers, traps or physical removal to prevent or reduce pest and disease problems
What is cultural control?
Is a procedure or manipulation (sound husbandry) of the growing environment, that results in weed, pest or disease control.
Crop rotation
cultural control
- Makes sure the same crop is not planted in the same place every year
- Breaks the life cycle of pests and diseases. Prevents numbers increasing, especially if they are able to overwinter in the soil
- Group similar crops together - Leaf crops > Root crops > Legume/other(potato here)
- Good for soil - avoids nutrient shortages. Legumes provide nitrogen in the soil which is needed by leaf crops
- Not so good against pests and diseases which are unspecific
- Pests examples - potato cyst nematode, club root in brassicas
- Benefical change in fungal and bacterial population in the soil
Disease resistant plants
Cultural control
- Resistance can occur naturally and scientists can use these in a breeding program.
- Disease can mutate so resistance may not last
- Informed planting - ‘right plant, right place’
- Cornus alba - better in water logged winter soil than a Mediterranean species
Methods of good management and work practice
Cultural control
- Keep tools and containers clean so infections cannot spread
- Cut out infected material and burn or take to rubbish dump
- Prevent injury to plants by making pruning cuts clean and providing wind breaks
- Good ventilation is important. Reduces spread of diseases
- Keep greenhouse humidity and temperatures at suitable levels so fungal infections don’t develop
- Make sure soil is well-drained to help stop the growth of soil borne plant disease that attack plant roots
- Hoeing also brings pests to surface to dry out or be eaten by birds
- Covering and regular clearing of water tanks to prevent breeding of fungi
Quarantining plants
- New material should be kept seperate from other plants
- Even plants can occasionally harbour pests
Types of chemical controls? (8)
Usually called ‘pesticides’ and include:
1. Weedkillers (herbicides)
2. Slug pellets(molluscicides)
3. Fungicide sprays
4. Animal repellents
5. Hormone rooting powders
6. Insecticides
7. Plant growth regulators
8. Lawn sand treatment
Main classes of pesticides (3)
- Plant derived pesticides (botanicals) e.g. Pyrethroids, rotenoids, nicotinoids
- Inorganic (synthetic insecticides) only maybe those based on bifenthrin for amateur use.
- Insecticidal soaps and fatty acids. Widely used where biological controls are used. generally less toxic to humans and short lived on the environment.
Deciding on pestcide to use (3)
- The type of plant that needs controlling
- The type and value of the crop
- The presence of any benefical insects
Four main types of pesticide action
- Contact - sprayed onto pests and absorbed.
- Stomach - e.g. slug bait
- Systemic poisons - sprayed on plants and absorbed by tissues. Pests eat the plant and absorb poison.
- Suffocation - oils block the breathing pores
Fungicides
- Either kill fungal spores or prevent them from germinating
- Regular use can cause resistance
Controlling risks of applying chemical control (6)
- Only use when properly justified
- Choose least harmful chemical to control organism
- Read instructions on label
- Wear correct clothing
- Apply under dry, wind free conditions
- Carefully store in secure, safe, dry place away from children and pets
What is biological control
use of natural enemies to reduce damage caused by pest or disease
What is chemical control
Use of a chemical substance intended to prevent or kill a destructive weed, pest or disease
