Integrated Pest Management (IPM)
IPM is an approach to dealing with pests and diseases that can affect plants in the garden without resorting to pesticides. It takes a holistic approach to the health of the garden, looking to integrated solutions that create an overall healthy ecology in the garden that prevents pests and diseases from emerging. It is not an overnight solution and takes some time to establish.
It was only after the second world war that synthetic insecticides became widely available. These fix-all chemical solutions were widely promoted and used in agriculture across the world often with devastating affects to wildlife and human health. In recent years a number of the worse chemicals have been banned. However, the gardening market for pesticides has continued unabated with new products emerging every year. As a result, most wildlife poisonings and most water contamination from pesticides now comes from the domestic use of these chemicals.
Integrated pest management, as the term infers, involves a range of management tools and tactics that can be used to control pests while minimising risks to plants, people, pets and the environment. It is an approach that considers many aspects of plant health, from planning and planting to pest identification and treatment. IPM focuses on developing an overall management strategy not just controlling one type of pest.
As with all things gardening, observation is everything. Many serious disease or insect problems can be halted or brought under control if spotted early enough. The problem is knowing what to spot.
With pest problems either the pest itself is spotted or, more often, the damage left by it is observed. With plant disease common sense must be used to notice the signs of sickness in a plant, either discolouration or disfiguration of the leaves, noticeable when compared to healthy plants.
The internet is most useful for diagnosing a pest or disease problem so what was once a laborious task of ploughing through gardening books can now be achieved with 20 minutes searching on the web. Matching visual images of pest or disease damage is now relatively simple, as is finding safe organic treatments (see below).
IPM succeeds because of its emphasis on preventative action over the longer term as opposed to quick fix chemical solutions. Building up and maintaining a healthy soil can be compared to a person taking their daily nutrient requirements and enjoying good health. A healthy soil fights of many soil borne diseases and by its natural breakdown process maintains a vitality in the garden for the plants growing.
Soil treatments such as seaweed contains trace elements such as iron, zinc, barium, calcium, sulphur and magnesium, which promote healthy development in plants. Seaweed fertiliser in mulch or spray form will enhance growth and give plants the strength to withstand disease. A seaweed mulch also repels slugs.
By maintaining a slightly acid soil (around pH 6.5) a number of soil borne diseases can be prevented (lime can be used to increase soil pH and sulphur can lower it). By forking over the soil before a winter frost pests overwintering in crop residues in the bed can be destroyed.
Plant crops and varieties that are suited to the soil and climate. In selecting varieties the choice is between standard generic F1 hybrids and the more natural organic and heirloom types. While the hybrids may be developed specifically for disease and pest resistance they often come with a proviso of using artificial feeds and pesticides to achieve this. As IPM aims to achieve an overall integrated balance in a garden this can include selecting plant types that are themselves more natural and recurring.
The best method of pest control in the garden is to keep plants healthy so they do not attract bugs or disease. By growing from seed you can avoid introducing disease or insects from somewhere else. Diseases and insects in young seedlings may start in greenhouses or plant beds and cause heavy losses in the garden. Always select only healthy, sturdy transplants with well-developed root systems for planting in the garden.
Use interplanting and companion planting in the vegetable garden as opposed to solid plantings of a single crop as this diversity utilises beneficial relationships between species and creates a natural protection against many pests and diseases. It also slows down the spread of diseases and insects, allowing more time to deal with them if they occur.
Space plants properly as overcrowding causes weak growth and reduces air movement resulting in increased insect and disease problems. Keep down weeds and grass as they often harbour pests and compete for nutrients and water causing weak growth. Leaf and other organic mulches are extremely effective for weed control, as are weed mats and plastic sheeting.
When watering be careful to avoid soil splash as this brings soil and soil-borne diseases into contact with lower leaves. Avoid injury to plants as broken limbs, cuts, bruises, cracks, and insect damage are often the site for infection by disease-causing organisms. Do not smoke when working in the vegetable garden. Tomato, pepper, and eggplant are susceptible to a mosaic virus disease common in tobacco and may be spread by hand contact.
Sanitise tools and equipment including stakes and wire cages prior to use with a light bleach solution as this can prevent lingering infections from being transmitted.
Remove and dispose of infected leaves from diseased plants as soon as they are observed. Severely diseased plants should be wholly removed before they contaminate others. These can be composted if the compost achieves high temperatures but otherwise should be disposed of with household waste. Avoid these lying about the garden.
Gardens can be untidy places but it is important to maintain clean disorder. Old sacks, boxes, baskets, wood and general rubbish will harbour insects and diseases in a garden. A good clean out is a good regular practice.
Watering can be the cause of many disease problems in a garden. It is always better to wet the soil and not the plant. Avoiding leaf splash or deliberately wetting the leaves is important as many plant diseases can take hold through the wet surface of plants. Avoid the temptation to wash bugs of leaves.
One of the biggest problems in gardening is over watering. In general gardeners use far more water than is required. Flooding a vegetable bed leaves the soil soaked and can encourage a number of soil borne diseases and attract various pests. It is important to time watering in the garden for evenings or early mornings and to monitor the quantity to avoid over watering.
Natural biological processes and materials can provide control of pests and disease with acceptable environmental impact and often at lower cost. In the first instance always hand-pick as many pests as possible. Avoid sprays until the population of insects has reached a critical level.
Where slugs are a problem, try to create drier conditions. Heavy mulches may encourage slugs while diatomaceous earth, coffee grounds, crushed eggshells, and hydrated lime near plants may help deter slug activity.
When interventions are required to deal with pests there are a wide range of natural remedies, most home made, which produce acceptable results. A relatively new commercial solution is Neem juice. This is a powerful natural pesticide holding over 50 natural insecticides. This extremely bitter tree leaf can be made in a spray form.
There a wide range of home made garden sprays that work very well with a variety of pests. Here are a few examples (there are many more):
Onion and Garlic Spray
Crush one clove of garlic and one medium sized organic onion in a pint of water. Wait one hour and then add one teaspoon of cayenne pepper and one tablespoon of liquid soap to the mix. This organic spray will hold its potency for one week if stored in the refrigerator.
Citrus Oil and Cayenne Pepper Mix
This works well on ants. Mix cup of hot water, half tea spoon cayenne pepper and 5 drops of citrus oil for spray bottle.
Red Pepper Spray
Red pepper powder can be used to create a homemade pesticide that is safe to use in vegetable gardens. Combine 1 tablespoon of red pepper powder, 6 drops of dish soap and 1 gallon of water and mix.
There are many home made pesticides that work relatively well. Often it is about identifying the one that works in a particular garden. Most use an element of washing up liquid to help them adhere, which does not harm plants. Some are made with baby shampoo. Tobacco is also a good general pesticide.
When spraying plants for pests it is important to do both sides of leaves and to avoid application in direct sunshine.
IPM is about exploiting beneficial relationships in the garden to maintain a healthy plant growth. This can be as simple as encouraging birds into the garden to eat insects or selecting plants for the garden that encourage hover flies and other beneficial insects to live there. Having a good selection of wild flowers in a garden creates excellent natural habitat for useful insects.
Complementary planting groups plants for beneficial interactions between them creating an overall healthy growing environment. Maintaining strong healthy plants in a clean and balanced environment is the best protection plants can have from pests and disease.
IPM is a system that is built up over several years in a garden. Pesticides kill pests and beneficial insects equally leaving the environment sterilised. This vacuum can encourage new infestations. IPM seeks to create a healthy living environment in the garden that is robust and self managing.