Pests and diseases : Prevention and treatment
To enjoy the beauty of your plants and flowers for as long as possible, you must adopt the same motto for your terrace and balcony as for your garden: “Prevention is the best medicine”. The first step has already been made if you make sure that you select healthy specimens when you plant your plants. Naturally, quality has its price but the investment is worth it because healthy plants are more resistant than weaker specimens.
Equally important for a good development, you need to choose the right location and treat the plants with care. Planting too close together or in too dark, damp places will encourage, as will excessive or insufficient watering and feeding. If the plants stand in too much water, they will rot and enable fungal diseases to attack the plant. If given too much fertiliser, the plant tissues will become too soft and thus become an easy prey to sucking insects such as aphids. Make sure that the plants are not placed too close together and that they can dry quickly after the rain to avoid fungal diseases.
Check your plants regularly for pests and diseases so that you can start treatment as early as possible if it should be necessary.
But you can also have useful insects on your balcony or terrace, which can exercise biological control of pests. The condition is that you do not use any chemical products to get rid of pests, since the chances are they would destroy benign insects as well. Ladybirds, wasp flies, green lacewing and other insects will come to establish themselves on your balcony or terrace of their own accord and often can work wonders by feeding off pests. Allow spiders to make their home among your plants because they eat aphids, midges and flies. Install nest-boxes and put water for birds or hiding-places for toads because they too are great consumers of pests.
The plants themselves will tolerate a certain number of pests without being damaged by them, so it is not necessary to be obsessive about destroying every pest. If there are enough natural enemies around and the biological balance is correct, you will not need to use chemical products. Sometimes however chemical pesticides will be the the only solution. In this case ask the shop or garden centre for products that will not kill useful insects. It is particularly important in treating flowering plants to make sure that the products you use will not be dangerous to bees.
Herbal preparations such as teas, decoctions and liquid manure, also available in garden centres as pre-pre-pared products, are strongly recommended because of their preventive, plant fortifying and insect-repelling properties. You can make these yourself very easily. As a rule of thumb, you should use 1 kg of fresh or 150 g of dried plants to 10 litres of water (2 lb or 6 oz to 2 gallons). The teas are made as you would normally for the tea you drink and left to draw for a little while, while decoctions should be boiled again after 24 hours. Both should be cooled down before using. Liquid manure should be allowed to ferment for about 14 days until it no longer foams and be diluted before spraying onto the plants. This is best done in the evening.
Fight pests and diseases with liquid manure, teas and decoctions: Use 1 kg (2 lb) of fresh or dried or 200 g (7 oz) dried nettles for 10 litres (2 gal) of water. If the smell of fermentation on the balcony or terrace bothers you, you can make a cold water nettle decoction, leaving the nettles to stand in water for 1-2 days and then spraying it undiluted on the plants.
Horsetail tea for combating mildew, rust and scab as well as red spider mites: boil 1 kg (2lb) of fresh or 150 g (5 oz) dried horsetail in 10 litres (2 gal) of water for 30 minutes, then drain. Dilute one part with five parts of water and spray onto the plants. Garlic tea is also very effective: 75 g (3 oz) of crushedto 10 litres (2 gals) of water. This tea can be used undiluted.
Parsleydecoction for combatting aphids and fungal diseases: 300 g (10 ox) of fresh or 30 g (1 oz) dried plants are left to macerate in 10 litres (2 gals) of water for 24 hours. They are then boiled for 20 to 30 minutes and left to cool down before spraying on the plants.