Spring is the season when a host of pest organisms come to life and feed massively on our garden plants. Foremost amongst them are species of tiny flying insects, known commonly as aphids, which while not generally fatal, cause a lot of visual damage to a wide range of plants.
The initial symptom of aphid activity is the secretion of sugary substances on new leaves, stems, and flowers. This can be extremely unpleasant with honeydew dripping on to paths, parked cars, and other plants. More dangerous to the plants' health is the sooty mold, which is a complex of fungi that develops from the honeydew. Left unattended, the soot blocks out light from reaching the plants' foliage, thereby depriving the plant of its vital energy source.
Before going into how to deal with aphids, remember that the purpose of pest control is not the complete eradication of the offending organisms, but rather the control of their population levels to manageable proportions. The indiscriminate use of insecticides only succeeds in clearing the way for pest populations to explode, as the insecticides reduce the population of natural predators. For this reason, quite apart from environmental considerations, it is best to avoid applying pesticides in the home garden altogether.
As intelligent pest management is about control and not elimination, non-poisonous, "environmentally friendly" insecticides, such as insecticidal soaps, can do a satisfactory job. Better still is to use the good old-fashioned garden hose at high pressure to wash off the aphids, with a little help from your thumb and forefinger. Will this be 100% effective? The answer of course is negative, which as previously mentioned, is a good thing in itself.
As aphids in the spring tend to attack young juicy growth, they are mostly found on the plants' growing tips, making it easy to remove them by simply clipping the plants lightly. This works perfectly for foliage plants such as Artemisia or Ivy, but of course might prove very unsatisfactory for flowering ornamentals and fruit trees. It is also possible to let nature take its turn. In the Mediterranean region for instance, periodic hot, dry winds kill aphids just as effectively as insecticides.
With pests in general and aphids in particular, timing is all-important. Ultimately, we should be striving to turn the garden into a balanced eco-system, but this is easier said than done. In the meantime, aphids should be treated at the first signs of infection.
One sometimes sees a gardener spraying the honeydew or even the sooty mold that has grown on the plants' foliage and stems - a case of shutting the barn door after the horse has bolted. Aphids produce a number of generations within a single spring, so there is every chance that the gardener is spraying the symptoms and not the cause itself.
