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Agronomy
Multiplication

Canna Indica is normally propagated by putting either the rhizome tips or the whole rhizomes in the ground. Because the rhizomes are quickly perishable, it is important to store them properly between the harvest and the next planting time. The large strains can be divided in spring, before the new shoots appear. However sowing is also very interesting, because a seedling started early in the spring is able to flower the same year it is sown.

Cultivation

The substrate must be rich, humiferous and light, the best substrate should be a deep rich well-drained soil in a sunny position with a pH in the range 5.5 - 7.5, but tolerating pH 5 to 8. The rhizomes should be planted at 10 cm deep, after the last frosts. Although it can tolerate dry periods, occasional watering will be beneficial for the yield. Canna is a plant that can withstand low temperatures (-10°C in regions with a mild climate). Nevertheless, the foliage is affected from 0°C. It can be found at elevations up to 2,000 meteres in humid tropical climate. It can also be cultivated in the subtropical and warm temperate zones. The best growth climate is found in areas where annual daytime temperatures are within 12°c to 32°c. It prefers a mean annual rainfall in the range 1,000 - 4,500mm, but can tolerates 500 - 5,000mm per year

Diseases

Cannas has relatively few diseases compared to other genera. Nevertheless, some disease have been recorded to affect they; Canna rust Puccinia thaliae, a fungus that causes orange spot on the leaves, plant viruses as Hippeastrum mosaic virus, tomato aspermy virus, Canna yellow mottle virus and Canna yellow streak virus which can cause mild or strong symptoms form streaked leaves stunted growth and distorted blooms and Botrytis, a mold that affects the flowers.

There are a lot of different Canna varieties of which some are resistant against some of these diseases. To prevent mold, the soil must be well drained without too much soil moisture or stagnating water.

Pests

The Canna leaf roller moth, Calpodes ethlius (Lepidoptera: Hesperiidae) has been seen on Canna plants in the USA. It is a caterpillar know as the worst pest for this plant and primarily found in the Southern United States. This pest causes damages by laying its eggs in the bud of developing stalk. To protect them from predators and insecticide, the caterpillars use sticky webs to keep the leaves from unfurling. The pupate then feed on the leaves which can lead to losses of yield due to reduced photosynthesis.

The Japanese Beetle, Popillia japonica is also a leaf ragging pest but with small consequences for the plants. This beetle eats on the part of the leaves between the veins. In its originating region in Japan it does not cause a lot of damages but in America it has no natural predator and can still cause serious damages on Cannas and a variety of other plants.

Bird Cherry Oat Aphids has been recorded affecting stored rhizomes. Although they have not been causing severe damages yet it can particularly affect plants grown in greenhouses and can be combatted with parasitical wasps. It is a more common pest on cereals.