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Oleum use side effects

Q: I recently sprayed one of my trees with "oleum" recommended as a virtual cure-all for insects and certain fungus diseases, but am rather alarmed to see that the leaves are turning brownish and am afraid that the tree may be dying. What can I do to revitalise it, and why did this happen?

A: Oleum is an oil-based emulsion insecticide and to a lesser extent a fungicide - the way it works is by clogging up the pores or breathing tubes by means of a thin oil film, plus poisoning the insect. Doing so, it virtually chokes the insect to death - especially the eggs and young larvae. The same oil film also stops fungus as this can only spread with the aid of moisture in the air. Now let us consider your tree, which also has to breathe as it were. If you spray with too strong a solution, you are clogging up all the leaf pores - the leaves are now unable to function, will turn brown (being not able to produce chlorophyl) and will drop off. Certain trees do not like oleum at all (ficus, etc.). In most cases, however, it will not be lethal as the tree will soon sprout a new crop of leaves, but with evergreens (needle and leaved varieties), I would recommend washing the tree with a weak soap solution to open the pores again. Please, in all cases, do not use a stronger solution than that recommended on the container; rather use a weaker one and spray at 10 day intervals if necessary.

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Random Bonsai Tip

You can bend thick, hardened branches by undercutting. A wedge is cut underneath where the bend is needed and then the branch is eased down anw wired into place. Thick, coarse branches could also be removed completely and replaced with new branches by thread grafting or approach grafting