Boron Deficiency in Banana
Boron is the most commonly deficient micronutrient in banana plantations. Boron’s primary role in banana is to act as a key component in a number vital process such as structure integrity of cell walls, cell division, root development, and membrane permeability of potassium (K+).
Boron is necessary for:
- Proper growth and development
- Pulp consistency
- Sucker development
Incomplete expansion and unfolding of the youngest leaf is probably the most typical symptom of boron deficiency. In very severe cases, interveinal chlorosis and leaf malformation occur. The leaves may be narrow, rolled, and incompletely developed. Sucker development is likely to be very poor.
Boron deficiency first results in the development of small chlorotic streaks aligned perpendicular to and crossing the primary veins of the leaf blade. As the deficiency becomes more severe, the chlorotic streaks become longer and more concentrated, eventually extending through the leaf and, in some cases, appearing as slight protrusions on the lower surface.
Leaf streaking has been recorded in cases of boron deficiency. However, such streaks usually coalesce, forming patches, and ultimately become large necrotic patches. The absence of necrotic patches and the appearance of malformed leaves enable boron deficiency to be distinguished from sulfur deficiency.
Blackening in the center of the pulp of the fruit has been observed in sand culture experiments. In the field the presence of amber colored gummy deposits (mostly towards the flower end) has also been associated with boron deficiency.
How much boron is enough?
- Banana plants remove significant amounts of boron from the soil each year. Once a plant shows signs of deficiency it cannot fully recover. Flowering may be regular however no fruit may be produced. Leakage of potassium from cell membranes may also occur. Always consult local department of agriculture to check the proper dose rates.
- Rates of boron fertilization should be based on yield goals along with soil tests and/or plant analyses.
Timing your boron application
- High demanding periods for boron are after harvest, blooming, and during fruit growth.
- Boron may be applied in dry or fluid blends. With dry bulk blend fertilizer, broadcasting before planting is recommended, using Granubor® 2.
- Boron may be applied broadcast in a semicircle around the plant using Fertibor®.
- Boron in liquid fertilizers may be broadcast or fertigated using Solubor®. This material may also be mixed with pesticides or applied to foliage in aqueous spray.