7

PESTS

BONSAI ARE AS MUCH SUBJECT to pests as other plants and, because of their size, are easily damaged. The whole symmetry of a bonsai can he destroyed by the withering of a branch or even a few twigs, and its beauty can be impaired by the discoloration of the foliage. The best protection against disease is the use of new soil in repotting, soil taken from a depth of at least three feet where grubs are unlikely to he found, and the constant exposure of the tree to sun and breeze. Trees and hushes in the garden near the bonsai ought to he sprayed against insects during the winter with a strong lime-and-sulphur solution and at intervals during the rest of the year with a weak solution of the same. The leaves and soil of the bonsai must he examined frequently for insects or mildew and treated immediately if there are signs of disease. This is best done by spraying from a can fitted with a very fine spray.

INSECTICIDES

The insecticides recommended. are solutions of pyrethrum and agricultural nicotine or sometimes pyrethrum and rotenone, all of which can be purchased at shops supplying garden requisites or at a chemist's. The amounts for making strong, medium, or weak solutions will he found in the directions on the bottles.

Powdered sulphur and lime can also he obtained easily and should he used in the following proportions. For a strong solution: 112 grams quicklime, 225 grams sulphur, and 1 liter water. For a weak solution: 22.5 grams quicklime, 25 grams sulphur, and 1 liter water. The lime and sulphur, in powdered form, are mixed separately, each in half the amount of water. They are then mixed together and boiled for fifty minutes. The solution turns brown.

When treating mildew a solution known as "Bordeaux mixture" (because it is used in the French vineyards) is the most effective. It can often be purchased ready prepared, but if not available it can be made as follows. For a strong solution: 6 grams copper sulphate, 1.5 grams quicklime, and 1 liter water. For a weak solution: 6 grams copper sulphate, 1 gram quicklime, and 2 liters water. The two ingredients are mixed separately, each in half the amount of water, and are then mixed together. The solution must never be kept in a metal container as the copper sulphate rots metal. It is best to use a wooden tub and do the mixing with a brush or wooden spoon.

COMMON PESTS

Ants. Ants appear from late spring to autumn in the soil and on the trunk and branches. On the tree they do no harm themselves, but they carry aphids and mealy bugs. They can be got rid of by spraying with a strong solution of pyrethrum and nicotine. If it is found that the ants have made a nest in the soil, the tree must be repotted immediately. The contaminated soil must be washed off the roots completely and the roots soaked in a weak pyrethrum solution for from five to ten minutes. New soil must be used for repotting and the old soil burned to purify it. This is done by sifting the earth onto a fire of embers. If the soil cannot be burned, it must be taken away and buried.

Aphids or plant lice. Aphids usually appear in spring and summer. They are found on the tops of new shoots and at the base of flower buds or on the backs of new leaves. Aphids look like tiny green or brown grains. They are easily killed off, but will return as easily and the tree must be examined constantly. They are treated with a medium solution of pyrethrum and nicotine. Ladybirds (the species, also called ladybugs, with seven spots on their backs) eat aphids and should be welcomed.

Boring insects. These insects appear from spring to autumn on the trunks and branches. Their presence can be recognized by the trails of slimy excretion they leave on the bark and by the holes they make. They bore into the wood and, if not dealt with immediately, may kill the tree. The best way to destroy them is to inject a very strong solution of pyrethrum or nicotine into the holes, using a clinical syringe with a heavy needle. The holes are then sealed up with clay or wax. If a hole is very large, it may require more than one injection. When the slimy marks no longer appear on the bark, the insect is dead.

Caterpillars. Caterpillars appear in spring and early summer and eat the young leaves. Their presence is easily recognized by the trails of slime they leave on the soil and branches. They can be destroyed by spraying with a medium solution of pyrethrum or rotenone.

Earthworms. Earthworms appear in late spring and early summer. They develop in the soil and their presence can be detected from disturbances on the surface. Pots left standing on the ground are easily attacked by earthworms, which is one reason why it is better to keep bonsai on a raised stand. Earthworms can be got rid of by spraying the soil with medium pyrethrum solution.

May-beetle larvae. These appear in late spring and summer. They are found in the soil and are very hard to get rid of. They are whitish-yellow insects with hard heads and half-moon-shaped bodies, between a quarter of an inch to an inch in length. They make disturbances in the soil similar to those of earthworms and are very dangerous because they eat roots. The only way to get rid of them is to wash all the soil from the roots and then repot the tree in new soil. The old soil must be burned as described in the section on ants.

Mealy bugs. These may appear at any season on the trunk and branches of a five-needle pine. They resemble minute pieces of white cotton fluff. In winter the tree should be treated both with a lime-and-sulphur solution (one part solution to thirty parts water) and with a strong pyrethrum mixture. In summer the lime and sulphur should be half this strength, but the pyrethrum can be used with safety. These strong solutions must never be used in the budding season as they will damage the leaf buds.

Mildew. Mildew develops from spring to autumn on the branches and leaves. There are many kinds of mildew, all detrimental to the tree and all producing similar symptoms-curious colored patches or growths on the bark and flagging leaves. The condition is best treated with Bordeaux mixture, but, if this is unobtainable, a solution of lime and sulphur can also be used.

Red spiders. Red spiders appear from spring to autumn, usually on juniper, cryptomeria, and pines. They cause the foliage to take on a greyish tinge and later to turn brown. The spiders are very small, no larger than a pinhead, and may be seen by holding a white paper or the palm of the hand under the foliage and then shaking the branches. The tiny red insects can be seen moving about on the flat surface. They should be destroyed with dusting sulphur or a lime-and-sulphur solution sprayed on the branches. Pyrethrum and nicotine can also be used. Several treatments, once every three days for at least nine days, are necessary to get rid of the insects. The spiders spread easily and the affected tree must be isolated, while any trees near it should be sprayed as a precaution. It takes up to three years for a bonsai to regain its normal color after being attacked by red spiders.

Scale insects. These may appear at any season but are commonest in autumn and winter. They are found on the branches and leaves and look like small white or brown shells or lumps. When the tree is dormant in winter the branches can be treated with a strong lime-and-sulphur solution to which some nicotine and pyrethrum is added. Several sprayings may be necessary to get rid of scale insects.

Color Plate 21. Rock cotoneaster. Root-over-rock style. 1'6". About 25 yrs. Produced from a cutting and potted about 15 yrs. ago. Glazed Chinese pot.

Color Plate 22. Hornbeam. Root-over-rock style. 11". About 25 yrs. Produced from a naturally stunted tree and potted about 15 yrs. ago. The round-moss planted on the rock at the base of the tree produces the effect of a natural mountain scene. Glazed Chinese pot.

Color Plate 23. Japanese red maple, garden variety "Seigen." Informal upright style. 1'6". About 25 yrs. Produced by grafting about 20 yrs. ago. Glazed Japanese pot of Tofukuii ware. Photo taken in early spring; a little later leaves turn dark reddish-green, and then red again in autumn.

Color Plate 24. Satsuki azalea, garden variety "Metsunami." Sinuous, clinging-to-a-rock style. 1'. About 20 yrs. Produced by cutting or layering. Glazed Japanese pot of Tofukuji ware. Only in recent decades have azaleas been trained into bonsai shapes, having been appreciated previously merely for their blossoms.

Color Plate 25. Miniature bonsai, produced during the past 30 yrs. by Mr. and Mrs. Raiiu Matsudaira. Left stand, reading left to right and tap Ia bottom: 1) Bear bamboo. 2) Oriental arborvita, from an 80-yr.-old seedling. 31 ficus foveolata var. nipponica, natural. 4) Trident maple, from a seedling. 5) Dworf Thunberg barberry, cutting. 6) Quaker ladies. 7) Common Ezo spruce, natural. Right stand: 1) Five-needle pine, natural. 2) Needle juniper, natural. 3) Ellisiophyflum pinnatum. 4) Dwarf sweet-rush. 5) Group planting with common cryptomeria, from cuttings. 6) Japanese grey-bark elm, from a seedling. 7) Bronze ornament.