There are two really persistent ‘bugs’ which trouble the gardener, or more correctly the plants in the garden. These are mealy bug and scale. Both of these horrors suck the sap out of plants, and will kill them if they are not controlled. The mealy bug is covered with a kind of cotton wool, which protects it from other predators and from light showers. The scale insects are just like limpet mines, and under their protective shield lay hundreds of eggs which develop into adults and in time have the same devastating effect as a limpet mine. I have seen hibiscus stems covered with hundreds of scale insects, and the plants dying. The main reason that they are dying is that the grower is using the same insecticide all the time with the result that the scale insects have become resistant to it.
The control of these two insects is relatively simple if you persist in the treatment until they are wiped out. The trouble is that many gardeners don’t persist for a long enough time. Just killing a few adults is not good enough. They have all got to be killed. You have got to get past the thick cotton-like covering of the mealy bug and under the protective covering of the scale insect.
But you must not keep on using the same insecticide all the time. If Malathion or Rogor are used continuously, then you are not only wasting your money, but contributing to the death of your own plants. You have to ring the changes. You must use different chemicals and change them after a few applications. Keep these little horrors on the wrong foot all the time.
Systemic insecticides offer the most effective control for most of the insects which suck the sap from your plants. They do not, however, suit all plants. Most of them should not be used on ferns, gerbera, orchids, petunias, zinnias and many others, and you absolutely must read what is written on the canisters, packets or leaflets. Quite apart from the damage you might do to your plants, you must be aware of the damage they can do to yourself, family, neighbours and pets.
Contact insecticides are the next method, followed by dusts and the good old finger and thumb method – killing them by literally rubbing them out. And in small quantities too. When you feel you have got the right insecticide then you should apply it in the late afternoon, when there is no breeze. Putting a little dish-washing liquid into the spray can help it stick to the leaves and stems, which will absorb it, just as the insects will absorb it from the sap. Providing the soil is not dry you can also water systemic insecticides onto the ground in the vicinity of the plant you’re to treat. It will be absorbed by the root hairs and travel throughout the entire body of the plant. If you haven’t got a sprayer then this is the easy way to do it. If the ground is dry and you water systemics onto it they will kill off the root system.
C ontact insecticides depend on the chemical being applied with sufficient force or in such a way as to penetrate the protective covering. Malathion is a contact insecticide, and its effectiveness depends on it actually touching the body of the insect. Again, spray in the late afternoon, and don’t forget the few drops of dishwashing liquid. Buy small quantities to start off with, and for your plants sake don’t keep using the same thing over and over again.
Until next week may your God go with you wherever you may be.
