Learn to tell the difference between pests
and other creatures
Managing pests and diseases and other causes of plant ill health
Introduction
Prevention is the key to success when dealing with plant problems. If you haven't already done so, check out the 'Keeping the garden healthy' section for practical advice.
Where specific problems are known to occur, there are a range of 'plant protection' barriers and traps that can be used.
When a specific problem arises, it is important to identify the real cause, so you can decide if any action is needed (many plants can live quite happily with some pest or disease infestation) and, if so, to plan an appropriate strategy for dealing with it. Remember that environmental factors such as waterlogging, frost, cold winds and 'human' factors such as strimmer damage or over feeding, can also cause symptoms on plants.
There are a few pesticide sprays that can be used in organic growing, but they are not harmless, and you should keep their use to a minimum. If you find yourself having to use pesticides regularly, despite using the other strategies suggested, then consider growing something different.
Managing pests and diseases
Best organic practice - the first choice
- Encourage biodiversity.
- Learn to tell the difference between creatures that can harm your plants and those that won't.
- Check plants regularly, squashing or picking off pests and infected foliage as they occur.
- Use other physical methods, such as shaking the plant or dislodging pests with a sharp jet of water.
- Consult Garden Organic's factsheets for information on a whole range of pests and diseases, and strategies to minimise their impact.
- Comfrey and other leaves used as slug baits and barriers
Acceptable organic practice
- Biological control agents - natural predators and pathogens that can be purchased for controlling specific pests. These are available from The Organic Gardening Catalogue.
- Plastic bottle cloches, home-made from used bottles
Acceptable, but not for regular use
Crop covers including horticultural fleece and fine mesh materials
Barriers and crop covers can be very effective, and harmless to wildlife. The main concern is the energy used to make them, their lifespan, and how they are ultimately disposed of. Recycling waste materials, and reuse of new materials, are preferable to single use of new materials.
- Netting, plastic and wire; gauge appropriate to size of pest
- Electric fencing
- Fruit tree grease and grease bands
- Yellow sticky traps, without added pesticides. For use in greenhouse/ conservatory only
- Cabbage rootfly mats, preferably home made
- Copper tape
- Granules, and other similar commercially available physical barriers, against slugs
- Pheromone baited sticky traps, not containing pesticides - for monitoring pest presence only
- Slug traps baited with beer or other attractants, not containing pesticides
Pest and disease control sprays
Any pesticide (including insecticides, fungicides and slug killers) that can be used in an organic garden comes under the 
Acceptable, but not for regular use heading. Although less harmful, and persistent, than many products, their use can still disrupt the natural ecosystem, and may harm creatures other than those that you want them to kill.
It is important to focus on all the other methods of dealing with pests and diseases, and to keep the use of these sprays to a minimum, and to avoid their use where possible.
Use only those products containing the 'active ingredients' listed below, and follow the instructions for use on the product label.
Specific pest and disease control products are available from The Organic Gardening Catalogue.
For pest control
Acceptable, but not for regular use
- Plant oils and other plant based products with a physical mode of action
- Starch based products with a physical mode of action
- Natural pyrethrum products (pyrethrins extracted from Chrysanthemum cinerariaefolium)
- Fatty acid potassium salt soaps
- Iron phosphate [Iron (III) orthophosphate] slug pellets
For disease control
Acceptable, but not for regular use
- Potassium bicarbonate (>99.0% w/w Potassium Hydrogen Carbonate (Bicarbonate))
- Sulphur products
For rodent control
Acceptable, but not for regular use
- Mouse traps
- Rodenticides, approved by the Pesticide Safety Directorate, used in tamper-proof bait stations
Do not use
Never acceptable in an organic garden
- Copper based fungicides. These guidelines recognise the environmental hazards of these products, and no longer recommend their use in organic growing.
- Any active ingredient/product not registered as a pesticide with the Pesticide Safety Directorate; this includes homemade pesticide sprays, washing up liquid, or any other household products
- Any other pesticide not included in these guidelines
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