Sustainability Flashcards
What are the 4 main methods of pest, disease and weed control?
Chemical
Physical
Cultural
Biological
What is meant by chemical control?
Use of pesticides to reduce pest populations.
This may be synthetic or naturally occurring compounds.
Both types will kill beneficial predators.
What are the benefits of using chemicals?
Fast acting.
Limiting the damage done to crop so that commercial stock is fit for sale.
Can be applied easily and all year round if pest present. Does not rely on certain temperatures.
What are the limitations of using chemicals?
Also kills beneficial insects.
Pests can become resistant if same chemical is used.
Crop residue can limit harvest time.
In enclosed areas - such as greenhouses - gardeners’ have to wear protective clothing and the area has to be closed to the public due to possible inhalation/contact with poisonous substances.
What is meant by physical control?
The physical removal or exclusion of the pest / weed. Eg. Netting, barriers, traps. Pinching out new shoots on beans which are covered in black bean aphid.
What are the benefits of using physical control?
Barriers are particularly affective for control of cabbage white butterfly. (Enviromesh) and do not harm beneficial insects.
Repeated mowing of grass to reduce perennial weeds also encourages a thick sward which is visually appealing.
What are the limitations of physical control?
Labour intensive and cannot be done on a large scale.
Need to know lifecycle of the pest.
Netting can be hazardous to birds if they become entangled in it.
What is meant by Cultural control?
Methods used to make the crop environment unsuitable for pests to feed, live or reproduce. Eg. Tillage method, resistant cultivars, rotation, planting dates, hygiene.
What are the benefits of cultural control?
Often based on preventative measures, so only requires careful planning rather than equipment/extra labour. Eg. Choosing to grow resistant varieties, or good hygiene.
Cheap method with no worry about Chemical build up.
What are the limitations of Cultural control?
Knowledge of biology of pest is required.
May not be immediate effect - such as stale seedbed method for weed control.
Many methods are preventative so long term planning is needed.
What is meant by the Biological control?
Use of natural organisms which prey on the pests and reduce numbers.
Biological control may be parasitic wasps, nematodes, mites.
Gardeners may have to introduce specific biological control indoors in a greenhouse setting to target a specific pest which has built up quickly.
Outdoors gardeners should encourage natural biodiversity so that beneficial biological control agents are part of the diverse food web. Eg. Ladybirds eat aphids. Beetles eat slug eggs.
What are the benefits of Biological control?
A natural sustainable, environmentally friendly method.
Does not impact on biodiversity.
There is no build up of resistance to pesticides.
They search and destroy, so do not rely on good plant coverage like pesticides.
What are the limitations of Biological control?
Some damage has to be tolerated - particularly outside.
Close observation of pest numbers is required.
In glasshouse once the pest has gone, the predator won’t have any food so will die. So pests need to be monitored and control may need to be reintroduced.
Some can only be introduced under certain environmental conditions so cannot be used all year round.
Requires knowledge of the pest lifecycle.
What is Integrated Pest Management? (IPM)
Integrated Pest Management combines several different approaches to pest and disease control to create an approach that is effective and environmentally sustainable.
IPM is based on an understanding of the lifecycle of the pest or disease, and it’s interaction with the environment.
With this information the grower can choose the most effective strategies for preventing and controlling the problem.
IPM uses all 4 categories of control, with chemical being a last resort.
What is meant by ‘Natural Balance’ in the garden?
Gardens are complex web of ecological activity containing producers (eg plants), consumers (eg slugs, birds, aphids, ladybirds. humans) and decomposers (eg. fungi and bacteria as recyclers).
Natural gardening encourages all types of insects and creatures which forms the food web. Creatures which the gardener calls ‘Beneficials’ such as ladybirds, hoverflies, frogs, hedgehogs etc.
Using chemicals upsets the natural balance of the garden. It will kill both the pest (aphid) and the benefical insect (ladybird). Then the aphids will bounce back more quickly than the ladybirds, and the spray will have to come out again.
