This article provides important information for growers of the American native Indian banana (Asimina triloba), a tree native to temperate humid climates. Unfortunately, there is limited scientific research on this plant, and the instructions are based on existing research and grower experiences. The goal is to help new growers successfully grow Indian bananas.
Indian banana details
Indian banana grows best in warm to hot summer temperatures and mild to cold winters. It is necessary that during the year the precipitation is evenly distributed, with a minimum of 81 cm of precipitation. The plant can be grown successfully in USDA zones 5 (-15ºF/-26ºC) through 8 (15ºF/-9ºC). The Indian banana grows naturally over a wide latitudinal range, from the Gulf Coast to southern Michigan. However, trees may have trouble cooling properly if planted too close to the Gulf of Mexico.
The varieties that are most successful come from the Midwest of the USA, the northern part of the Indian banana’s natural range. A national regional trial of varieties is currently being conducted to identify the most suitable for different parts of the country, but the results are not yet available. It is recommended to choose varieties that have been grown in climatic conditions similar to those in which they will be planted.
The Indian banana can grow in the shade, but the best yields are achieved in open places with protection from the wind due to the large leaves. Seedlings are very sensitive to full sunlight and may die if exposed to direct sunlight. For the first years, and sometimes for the second, shade is necessary, because the Indian banana naturally appears as an understory tree.
The soil for planting should be slightly acidic (pH 5.5-7), deep, fertile and well drained, while heavy and water-saturated soils are not suitable. In nature, the Indian banana is a small tree that rarely exceeds 25 feet in height. In full sun it develops a narrow pyramidal shape with dense, hanging leaves down to ground level, while in the shade it has a more open canopy with several lower branches and horizontally arranged leaves.
Cultivation of the Indian banana
Propagation of Indian banana seeds can be slow, but with the right methods, the process is not difficult. It is important that the seeds are not frozen or dried, as this can destroy the immature embryo. If seeds are dried at room temperature for 3 days, germination may be reduced to less than 20%. In order to break dormancy, the seeds need to go through a cold, moist stratification period of 70-100 days. This can be achieved by sowing the seeds late in autumn and allowing them to overwinter; the seeds will germinate next year between the end of July and the end of August.
Alternatively, the seeds can be stratified in a refrigerator (32º–40ºF/0º–4ºC), where they should be stored in a plastic bag with some moist sphagnum moss to preserve moisture and prevent fungal growth. After stratification, the seeds are planted 2.5 cm deep in well-aerated soil with a pH of 5.5-7 and an optimum temperature of 24º–29ºC (75º–85ºF).
It is recommended to use tall containers, such as 35-45 cm high tree pots or 25 cm high root trainers, to allow the growth of a long taproot. The seeds usually germinate in 2-3 weeks, and the shoot appears in about 2 months. Germination is hypogeal, which means that the shoot emerges without cotyledons. During the first two years, growth is slow while the root system is established, but after that it accelerates. Trees usually begin bearing fruit when they reach a height of 6 feet, which can take anywhere from five to eight years.
Clonal breeding of Indian banana can be achieved using various grafting techniques, including whip-and-tongue, cleft, bark inlay and chip budding. T-grafting proved unsuccessful. Pruning with soft and hard cuttings is almost impossible. Although the Indian banana can sprout from the roots, clonal reproduction by transplanting root shoots is often unsuccessful due to fragile and fleshy roots with very few fine hairs. The best results are achieved by transplanting in the spring when the new vegetation begins, or immediately after.
If many roots are lost, it may be beneficial to prune the top to match the remaining roots. A grafted tree can start bearing fruit in just 3 years.
Indian banana tree
Indian banana trees available from nurseries are usually seedlings or grafted varieties. Seedlings are usually annual and cheaper, while grafted varieties, which are biennial, provide a guarantee of fruit quality because they retain the clonal identity of the parents. It is recommended to buy at least two genetically different trees (two varieties or two seedlings) to enable cross-fertilization. Trees grown in containers have a higher survival rate than those taken out of the ground, due to the long taproot and delicate root system that can be damaged when taken out of the ground.
When planting trees, leave a distance of 2.5 meters between them. Water the newly planted tree immediately and as needed during the growing season. The Indian banana requires adequate soil moisture, especially during the first two years after planting. To reduce transplant shock, it is recommended to provide temporary partial shade. Application of a balanced fertilizer (20N-20P-20K) every few weeks during the first half of the growing season can improve the growth and establishment of young trees.
Protection
Pollination can be a challenge for fruit set, because the flowers are protogynous, which means that the stigma matures before the pollen and is no longer receptive when the pollen is released. The tree is self-incompatible and usually requires pollen from a genetically different tree. Natural pollinators, such as various species of flies and beetles, are often ineffective. Hand pollination can help: using a small brush, transfer pollen from the anthers of one clone to the stigma of the flowers of another clone. Pollen is ripe when it is a brown, loose ball of anther; the stigma is ripe when the tips of the pistils are green and shiny. Overloading the tree with fruit can cause smaller fruit and break branches due to the weight.
In nature, the Indian banana has few significant pests. The most serious is Talponia plummeriana, a moth larva that feeds on the fleshy tissue of flowers, which can cause the flowers to drop. Another pest is Eurytides marcellus, the zebra-tail butterfly, whose larvae feed on young leaves, but not in large numbers. The surface of the fruit can sometimes be covered with hard, black spots due to fungal infection, but this rarely affects the taste. Deer will not eat leaves or twigs, but will eat fruit that has fallen to the ground. Also, male deer can damage trees by rubbing their antlers against them in winter. Outside the natural environment, the Indian banana can be attacked by pests due to the stress of unsuitable soils and climatic conditions.
Sources: Kentucky State University Plantura, Agro Saveti
Source: boljazemlja.com
