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Fourteen Favorites Among the Perennials: Japanese

Japanese Iris (Iris kaempferi). The stately Japanese irises fortunately come into bloom when the beauty of many of the other perennials has passed. They prefer a moist situation and are most happily at home when naturalized along a stream or about the edges of a pool. They do, however, adapt themselves quite well to the open border, and, unlike most of the other irises, they have a decided preference for soil low in lime content.

They should be planted during the latter part of August or in early September. Spring planting is sometimes practised but is not so successful as early autumn planting.

In dry seasons Japanese irises respond generously to liberal watering before and during their flowering period.

The Iris Borer. The iris borer is a wicked little creature, difficult to control. The eggs are laid by a night-flying moth early in the autumn. They are deposited near the base of the leaves, where they winter, hatching out usually during the early part of April. The young larvae pierce the leaves and begin to eat their merry way downward toward the rhizome, where, if their peregrinations continue, they work such havoc that the plant is entirely destroyed. As the larvae work within the leaves they are somewhat difficult to detect at first, although their presence may usually be recognized by the characteristic "bleeding" of the plant. By the middle of July or early in August the larvae have usually reached their full size, being about one and one-half inches long. They then pass into the pupa stage, which is of short duration, lasting only three weeks, at the end of which time the adult moth emerges and the life cycle begins again.

Control measures are difficult. In small gardens the plants can be watched carefully in the spring and upon the first sign of trouble, detected by the bleeding of the plant, the young larvae may be destroyed by crushing them within the leaves. On a large area this method is not practical. Another measure of control which has recently been recommended is the burning of the old leaves in March before the eggs hatch. This must be done with great care, the leaves being loosened with a rake and a quick fire run through them. Unless precautions are taken the rhizomes themselves may be seriously injured by the fire.

Bacterial Rot of Iris. The iris is, most fortunately, subject to very few diseases. The only one that is of any economic importance is iris rot. Rot is a bacterial disease and has been very troublesome within the past few years in more than one section of the country. It is usually first detected by the yellowing of the leaves, caused by rotting at the base. The soft, pulpy mass is characterized by a very peculiar and unpleasant odor, and can be easily distinguished from rotting due to any other cause, such as injury, or too deep planting. The disease is more prevalent in wet seasons than in dry seasons, and irises which have been planted in damp, poorly drained situations are particularly susceptible.

The most satisfactory measure of control is to lift diseased plants and carefully to cut away all affected portions. The rhizomes should then be dipped into a one-per-cent solution of formalin (one and one-half tablespoonfuls of formalin to one quart of water) or into a very weak solution of potassium permanganate. They should then be replanted in clean soil. When the disease has been discovered in its very early stages, the rotted portion may often be successfully scraped away without disturbing the root system, and the plant may then be watered with a weak solution of the permanganate. A sunny, well-drained location and clean cultivation will do much to discourage the inroads of the disease.