First Aid for Bonsai
by Pieter Janse van Rensburg
When we water our bonsai as much as we need to during times of high daily temperatures and strong drying winds, we wash all the nutrients from the soil. It is important to replace these nutrients in the soil with a regular feeding program. A small dose of a balanced fertiliser every two to three weeks works wonders for our trees. Re-place all the trace elements once or twice a year by applying something like "Trelmix". This prevents leaf yellowing (chlorosis). Too heavy a dose of fertiliser will cause rootburn. If this happens, try to leach out the excess fertiliser by placing the tree under a tap, with the water running into the soil slowly at a constant rate.
If your tree has suffered a dry spell, it is a good idea to place it in a sheltered position for a week or two. Water it carefully during this time. Allow the surface soil to dry out somewhat before re-watering. In extreme cases take a plastic bag and some wire and fashion a temporary greenhouse cover for the tree.
Check regularly for pests and diseases. Be very con-scious of ants they are usually a telltale sign that other pests are present. They like the honeydew secreted by aphids. Fungi grow easily on the honeydew and the ants help to spread the spores. A strong jet of water often takes care of them, but if they persist use a good pesticide.
If the bonsai tree is in stress or looks unhappy, a tonic is in order. An excellent product is "Superthrive", only a drop or two in a litre of water sprayed over the leaves and on the soil usually works wonders. I also use "Rescue remedy" and vitamin Bl or B12 with great success (both tablet and fluid available at your local pharmacy). Crush the tablet and water it into the soil. It is an anti-shock treatment when I repot my bonsai, and I rarely have failures.
When we wire our trees, a branch sometimes snaps accidentally. If the bark is still intact, on at least one side, all is not lost. Clean away the splinters with bonsai shears, apply some tree seal to the wound and bandage the area with florists' tape, masking tape or insulating tape. This strengthens the area and healing takes place faster in the dark.
If we have missed the potting season and a tree is pot-bound and starting to deteriorate, it is safer to transfer it to a larger pot until the following spring, especially if it is an old tree. A young tree can be given a very light re-potting for it to survive until next spring, only trim off the outer roots that are coiling around the bottom of the pot.
Olive trees are prone to root-rot. Try to keep them slightly drier than usual and do not grow them on the usual gravel tables. It is better to grow them on wooden or wire mesh tables. The first sign of such a problem is that branches start to wither and die. In extreme case parts of the tree will die. Three treatments of "Ridomil" or "Aliette" normally destroys the fungus.
If damage occurs to the trunk of a bonsai tree through rot or insect infestation and it not usual to carve it into a feature, repairs must be made. A short-term solution is to carve out the damaged area and it fill it with Pratley putty. The area could be camouflaged with pieces of bark or paint it in a matching colour. A long term solution is to allow a sprout, near the damaged area, to grow unchecked to help the formation of callus around the wound. If the tree is in particularly bad shape and all its leaves have dropped and it may be on its way out, do not despair! Scratch the bark and if it is green, there is hope. Wash all the soil off the roots, trim off all dead portions and plant it in coarse sand or gravel. Treat it as a new cutting and you might be pleasantly surprised. It is often possible to revive at least the trunk. If this happens, water it often with a "Superthrive", vitamin BI or BI2 solution to help it through its period of stress. If the worst does happen and the tree dies, please do not give up in disgust! Try to establish what happened so that you might avoid a similar occurrence. Enjoy your bonsai.