While banana plants flourish in temperatures between 20°C and 30°C, growth slows down and plants enter a dormant state when temperatures fall below 14°C. Below 10°C, damage becomes a likely reality. Even subtropical plantations face low temperatures in winter, leading to occasional light frost or wind chill damage. The extent of cold injury depends on factors such as minimum temperature, duration of exposure, and the plantation’s age.
How to spot cold damage
Winter chill damage to young leaves
Chill damage occurs between 6°C and 1°C, turning banana leaves yellow due to chlorophyll destruction. Leaves develop yellow or necrotic patches, reducing the plant’s efficiency. Minimal damage occurs at 6°C, but severe yellowing and necrosis happen at 2°C. Strong winds can worsen the damage by causing leaf stripping and chilling.
Frost damage to bananas
Frost damage is caused by ice formation in intercellular spaces, disrupting cell membranes and walls. Frost can kill banana leaves rapidly, with just a few minutes below 0°C enough to ruin a plantation. Frost-damaged leaves show dark, water-soaked areas that desiccate and turn brown. Complete defoliation delays bunch formation and reduces yield. These effects might not be visible until months after the frost event.
Young transplants growing through a cold winter may see the die-back of younger leaves, with the pseudostem turning black. Warmer spring conditions allow new leaves to emerge, forming a second pseudostem. If the growing point is damaged, a side sucker will replace the parent.
How to manage a frost-damaged plantation
The first steps of managing a frost-damaged banana plantation involves considering the plant’s growth stage, condition at the time of injury, and post-injury weather. Remember that at least 4 to 6 healthy leaves are needed for a young banana bunch to develop properly.
Then, treat each plant based on its condition:
Young plants damaged by cold/frost
- Continue growing, but with delayed flowering.
- If the growing point is damaged, a side sucker will replace the parent.
- Produce smaller bunches.
Nearly mature bunch at frost occurrence
- Harvest or leave the plant for up to a week to fill out on residual reserves. Avoid leaving it too long to prevent premature ripening.
- Apply blue bunch covers to protect from sunburn.
Newly emerged or 50% mature bunch at frost occurrence
- Bunch will not develop enough to be marketable.
- Cut the bunch and use it as mulch or compost.
- Cut down the damaged canopy, but only after the risk of further frost has passed, to protect suckers.
Pre-flowering plant
- Allow it to produce a bunch.
- Ensure there are four or more green leaves for bunch filling.
- If fewer than four green leaves remain, remove the bunch and cut the canopy down.
Aftercare: Recovering from cold/frost damage
Leaf cutting
On young transplants, do not immediately remove frost-damaged leaves since these leaves still add an extra layer of protection to the stem and growing point. Early leaf cutting will not promote recovery. Only remove frost-damaged leaves when temperatures start to increase and new leaves appear.
Irrigation
When leaves are lost, transpiration from the plant is greatly reduced. Therefore, reduce the amount of water administered. Excessive irrigation does not result in rapid recovery but may result in root damage and minimal nutrient movement below the root zone. Apply normal irrigation when the plants regain their normal foliage development and canopy density.
Weed control
Weed control will be essential to rapid recovery from frost damage, as weeds will compete heavily with the plants for available water, nutrients, and light. Foliage lost can result in additional weed pressure due to the increase of sunlight within the plantation.
Conclusion
A frost event is one of the most devastating environmental stresses to banana plants. However, banana plants are vigorous and can recover quickly from cold damage. With proper care, plants suffering from leaf damage can be expected to return to pre-frost conditions within a year. Growers should properly evaluate the extent of cold damage to banana plants, and then follow the appropriate recommended banana cultural practices to allow for plants to recover satisfactorily.