Keeping Bonsai Healthy
Bonsai are sensitive trees, demanding more care and precision in, training and repotting than any other plants. The very restricted environment they have to live in makes them particularly susceptible to pests and diseases. Preventive treatment helps, and a constant watchful eye should be kept on your bonsai to catch any infection at the earliest stage and eradicate it with the right treatment. These dangers are compensated for by the fact that all bonsai are trees or shrubs, and so by nature are robust.
Bonsai are particularly prone to attack by a variety of pests and diseases. This problem is exacerbated by the very restricted habitat in which they are grown. Because of their reduced size, they are more drastically affected by pests than their giant brothers in the forest. Yet it cannot be said that bonsai growing techniques actually aggravate the situation (except with greenhouse-grown tropical plants). The most effective preventive treatment is regular cleaning of the plants, to avoid creating conditions favourable to pests and diseases.
After pruning or pinching, make sure that the earth around the base of the trunk is free of leaves and other plant debris. Otherwise the debris is likely to decompose and create just the right conditions for fungal diseases or moss, which set up . This will eventually lead to the death of the tree.
You can buy purpose-designed brooms to sweep away the debris.
Though decorative to look at, moss forms a good refuge for pests and their larvae. It is for you to decide whether its decorative value outweighs any threat it poses to your bonsai.
If you decide in favour of moss growing on the, keep it well away from the trunk and branches. Use a special spatula or a hard nylon toothbrush to scrape away unwanted moss. In any case, thin out the moss on a regular basis. A close relative of moss is liverwort. In all instances this should be removed from the soil surface and thrown in the rubbish bin afterwards. If you just allow it to fall on the ground it will re-root and the will soon find their way back to the trees. With a few exceptions, take care not to damage the bark or cut into the wood.
Use insecticide to treat any larvae or greenfly you spot in the moss.
You may feel that grass around the base of the tree looks very attractive, but do remember that, besides the risk of pests and diseases, grass can take nutrients from the soil to the detriment of your bonsai. It is a good idea to weed through occasionally, and also aerate the surface soil.
Besides these preventive treatments, keep a constant eye on the plant and check the state of the leaves particularly looking underneath the leaves and the trunk, since pests may lurk in the bark.
If you find greenfly or larvae, treat with insecticide at once. Scrape away any loose bark from older trees, which may have started to flake off. If you find dead wood in the bends of any of the branches, or in any holes or cavities, remove it with the aid of a scalpel (like those used for), cutting down to the live wood, which should then be protected with mastic to help it heal. This may appear drastic, but it is the only way to stop the rot spreading.