The idea of a healthy garden, rather than simply pest and disease free plants, is at the heart of organic growing. The first part of this section, Keeping the garden healthy, looks at ways of maintaining a garden with a diverse, vigorous, ecosystem that can, to a great extent, look after its own well-being. More specific action is only taken as necessary against particular pests, diseases or adverse environmental factors. This is covered in the section Managing pests and diseases, (pages 25-28). Keeping the garden healthy Use the information in all sections of these organic guidelines, combined with good horticultural practice, to help you create and maintain a diverse active ecosystem in your garden, both below and above ground. General gardening Best organic practice the first choice Create a fertile, biologically active soil. Add composted organic materials to help reduce soil pests and diseases, and increase plant resistance. Use a crop rotation, minimum four year, for annual vegetables (see page 9) Grow plants that suit the location and soil type Start with healthy seeds, tubers, plants, fruit bushes, shrubs and other planting material, certified disease free where possible Grow varieties with some resistance to pest and disease Choose sowing and planting dates to avoid specific pests and diseases To reduce risk of diseases developing, prune trees and bushes, design plantings, and keep greenhouses and other protective structures well ventilated, to allow a good airflow When watering, apply water to the soil rather than the plant foliage Ensure plants have an appropriate supply of water www.gardenorganic.org.uk 21
Biodiversity Best organic practice the first choice Grow a diversity of plants to provide food, shelter and habitats for predators, parasites, and other wildlife Leave some relaxed areas, such as leaves under a hedge, weeds, or an area of longer grass and for example, to feed and shelter wildlife There will always be pests present, but they do not always create a problem. They are also a necessary source of food for valuable predators and parasites Learn to recognise the many creatures, from hedgehogs to hoverflies, which consume pests, and disease-causing organisms, as part of their diet Where practical, grow a mix of types and varieties of plant to reduce risk of pest and disease infestation and spread. This includes companion planting Plant tonics, stimulants and microbial products Plant tonics and biostimulants may help to promote plant growth and boost a plant s natural defences against pests and diseases. Home made compost teas Liquid seaweed extract Microbial products, including mycorhizzae 22 Tel: 024 7630 3517 enquiry@gardenorganic.org.uk
Cleaning greenhouses and other structures, and pots, tubs and other containers Best organic practice the first choice Pressure-washing Hot water/steam and scrubbing Natural plant essences including citrus juices Natural cleaning products such as vinegar, bicarbonate of soda Garden Organic factsheets Crop rotation Companion or mixed planting Organic pest and disease control Various wildlife gardening factsheets Water use in the garden See also: Factsheets on page 9 www.gardenorganic.org.uk 23
Managing pests, diseases and other causes of plant ill health Prevention is the key to success when dealing with plant problems. The section Keeping the garden healthy (pages 21 23) covers ways in which this can be done. When a specific problem arises, it is important to identify the 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. Note that environmental factors such as waterlogging, frost, cold winds and human factors such as strimmer damage or over-feeding, can also cause plant symptoms. Where problems are known to occur regularly, there are a range of plant protection barriers and traps that can be used. 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 perhaps you might consider growing something different. 24 Tel: 024 7630 3517 enquiry@gardenorganic.org.uk
Biological and physical methods Best organic practice the first choice Encourage biodiversity Learn to tell the difference between creatures that can harm plants and those that will not 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 Learn about the life cycle of pests and diseases to help develop strategies to combat them Use comfrey and other leaves as slug baits and barriers Acceptable organic practice None Biological control agents. These are natural predators and pathogens that can be purchased for controlling specific pests. Plastic bottle cloches, home-made from used bottles Crop covers including horticultural fleece and fine mesh 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 or conservatory only, unless for monitoring pest presence Cabbage root fly 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 www.gardenorganic.org.uk 25
Barriers and crop covers Barriers and crop covers can be very effective, and harmless to wildlife. The reason they are in this category is because of concerns over the energy used to make them, their lifespan, and how they are disposed of. Try to recycle waste materials, and avoid single use of new materials. Garden Organic factsheets Detailed factsheets on a whole range of pests and diseases are available. They can be found on www.gardenorganic.org.uk, or contact Garden Organic for a full list. J Lillywhite 26 Tel: 024 7630 3517 enquiry@gardenorganic.org.uk
Pest and disease control sprays Although less harmful than many pesticides, the products listed here can still disrupt the natural ecosystem, and may harm other creatures. Avoid their use where possible, and concentrate on using all the other available organic methods. Use only those products containing the active ingredients listed below. Always follow the instructions for use on the product label. For pest control 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 Microbes and microbal extracts such as Bacillus thuringiensis (Bt) note that products containing Bt are only available to professional growers For disease control Potassium bicarbonate (>99.0% w/w Potassium Hydrogen Carbonate (Bicarbonate)) Sulphur For rodent control Mouse traps Rodenticides, approved by the Pesticide Safety Directorate, used in tamper-proof bait stations www.gardenorganic.org.uk 27
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 the Garden Organic Guidelines J Bartlett 28 Tel: 024 7630 3517 enquiry@gardenorganic.org.uk