Organic Chemical Controls for Pest, Disease and Weed Control
Pests, diseases and weeds
If plants become severely, or even mildly, infested by a pest the normal reaction of most gardeners is to reach for the nearest spray-gun. Chemical controls are unquestionably efficient and destructive, quick and time-saving. Pests are killed rapidly by man-made chemicals and some are long-lasting.
Unfortunately, many chemicals also kill pollinating insects, such as bees, butterflies, moths and hoverflies, together with other insects which are predatory or parasitic on the very insects for which the insecticide is intended. Similarly, many garden pests and diseases — and now also some weeds — are becoming resistant to these chemicals and to successively produced new ones.
Chemicals are expensive, they need to be applied frequently in many cases, and they have effects not only on the soil, but also on discharges made into ground water and hence rivers and seas. There are a variety of ways in which pest, disease and weed problems can be overcome without the use of chemicals, and it is well worth considering them.
In a garden where no pesticides are used at all, the natural balance can operate and prevent the large and detrimental build-up of a particular insect to plague proportions. Predators and parasites can live and breed — ladybirds and their larvae, and hoverfly and lacewing larvae all feed on a variety of aphids such as greenfly, blackfly and the plum leaf-curling aphid; ground beetles and centipedes attack small insects and slugs in the soil; and the red velvet mite feeds on other mites. There are many more examples of this natural control of insects, and of larger creatures — snails by thrushes, for instance.
Fungal diseases can be prevented by applying the correct method of cultivation and taking special care with soil management. Weeds, too, can be eliminated by cultural practices such as thorough hand-weeding or hoeing.