How to improve banana health

It will also provide good shading of the bunch.

Regular de-suckering and finger thinning from banana bunches will ensure reserves are directed to productive growth of the selected ratoon and bunch.

Source of nitrogen is particularly important. Urea-based fertilizers have an effect on long term soil acidity, reducing the pH and increasing the requirement for lime.

They will also reduce root growth and health and increase the risks of disease. Field observations have shown that at pH's of below 4.5 the disease Sigatoka is more prevalent.

Care has to be taken with the use of all sources of nitrogen to minimize leaching and 'little and often' applications are advisable.

It is important to maintain a good balance between potassium and nitrogen use. A high potassium:nitrogen ratio can cause 'yellow pulp' (e.g. in West Africa). A low K:N ratio reduces resistance to wind damage and results in 'finger drop' (Dégrain) of ripe bunches at harvest.

Finger drop is most severe in the high temperature tropical conditions, where applications of ammonium-nitrogen alongside potassium result in the ammonium ion competing with and restricting potassium uptake. This competition is largely due to restricted nitrification under the high temperatures.

High levels of potassium lead to an imbalance with magnesium and calcium. Lack of magnesium results in leaf "blueing". Poor supply of both calcium and magnesium results in reductions in yield and fruit quality.

Optimum soil ratios for potassium to calcium and magnesium are given in Optimum Ca, K and Mg Ratios in Soil.

Trials suggest the balance in leaves between potassium, magnesium and calcium is important for banana yield.

Calcium is important for strong cell wall formation and thus has a major effect on plant and fruit integrity and health issues. It also serves as an enzyme activator, and is involved in cell division stimulating growth of roots and leaves. Calcium is particularly important for yield and quality, and uptakes are usually around 3kg/t of crop produced. Most uptake occurs before flowering and it is important that supplies are available early in the growth cycle of both plant and ratoon crops to satisfy plant and fruit needs. Calcium is important for rooting, and where the element is in short supply, roots can darken and rot.

Calcium Nitrate was tested being the more efficient Calcium source, when compared with other Calcium sources in a trial in Colombia.

Calcium also decreases the incidence of maturity spot, stain and bronzing on the fruit at harvest.

There are indications that use of calcium nitrate decreases the incidence and severity of Black Sigatoka. In Philippine trials with Tropicote the incubation period for the development of the disease was slightly increased, leading to a highly significant delay of infection progress on the plant from the 9th leaf of control plants to the 10th leaf of treated plants. This could be linked to calcium nitrate's effect on improving or maintaining soil pH as the incidence of Sigatoka is worse in acidic soils.

Manganese

Manganese is essential for respiration, N metabolism and chlorophyll synthesis boosting yield and plant growth Acid soils may have relatively high levels of manganese. In these situations the manganese can compete with and restrict the uptake of other nutrients. Where manganese toxicity is a problem, leaf concentrations may reach 6000 ppm, with the result that the 'green life' of fruit is reduced, contributing to the disorder known as 'mixed ripe'.

Liming is needed to minimize the effects of manganese toxicity. Care is needed, because over-liming can result in deficiencies of manganese, zinc and other elements.