Banana Production Kit: Banana Field Planting and Cultural Management Part 2

A banana plantation sustained by irrigation

Irrigation and Drainage
The banana plant needs a lot of water. Water shortage has an effect on the rate of plant growth, bunch development and the quality of the fruits.

Thus, farmers need to have at least furrow irrigation, watering hoses or even cans for watering purposes. Usually, smallholder farmers build furrow irrigation where the crop is grown on ridges between small, parallel channels made to carry water in order to irrigate the crop.

Furrow irrigation may also be used for drainage purposes since too much water may cause the roots to rot and die resulting to decreased amount of roots, root growth and yield.

Example Drip irrigation in a banana plantation

When to irrigate?
The need for irrigation can be assessed through soil and plant inspection though these are not accurate methods.

Soil Inspection
Examining only the soil surface is not an accurate method to assess soil moisture. To know what is happening below the surface, digging is necessary. Only then, you can really assess whether irrigation is needed.

Plant Inspection
Inspecting the plant for symptoms of water stress (leaf folding and wilting) is not recommended since by the time the plant begins to show symptoms of water stress, damage has already been done and not even immediate irrigation can undo the damage.

Irrigating on a fixed-time basis
Applying irrigation according to a fixed schedule (e.g. twice a week) is a simple method but not necessarily the best as it may easily lead to over- or under-watering.

Example Drip irrigation infrastructure

For tissue cultured plants, irrigation must be done lightly (5 to 10 mm) and regularly (every 2 days) for the first couple of weeks until the root system becomes better established. If tissue cultured plants are not optimally managed initially, their ultimate yield potential and advantage over suckers, corms or bits will not be fully realized.

Water distribution of different irrigation systems

Fertilization
Banana plants need some elements essential to plant growth such as Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), Magnesium (Mg) and sulfur (S). In order to correct deficiencies in these elements, there is a need to fertilize.

Fertilizer needs vary from one area to another depending on specific conditions. Soil and leaf analysis data will provide sound basis for good management decisions on fertilizer application. For small-scale farmers who do not have access to laboratories performing soil and leaf analysis, looking at deficiencies/excess symptoms in plants may be an alternative, but with inspecting plants for symptoms of water stress, damage has already been done by the time you observe the symptoms.

Deficiency/Excess Symptoms
Looking at deficiency/excess symptoms in the plants should be your last option because yield and fruit quality will already be affected by the time deficiency/excess symptoms are visible in the field.

Main symptoms of mineral deficiency in bananas:

Nutrient:Nitrogen (N)
Symptoms on leaf blades:

• All leaves: uniform light green or pale yellow color
• Weak bunch
• Widely spaced hands
• Reduced fruit quality

Additional symptoms:

• Pink petioles and pseudostem
• Slow growth
• Rosetting
• Bunch weight and fruit quality affected

Nutrient:Phosphorus (P)
Symptoms on leaf blades:

• Old leaves: saw tooth marginal chlorosis
• Young leaves: dark green purple color

Additional symptoms:

• Petiole breaking
• Rosetting
• Stunted growth
• Poor root development
• Curling of leaves 
•  Zinc deficiency

Nutrient: Potassium (K) 
Symptoms on leaf blades: Old leaves only: golden-yellow-orange chlorosis; brown scorching along margins, purple mottling at the base
Additional symptoms:

• Leaf bending
• Leaf desiccation
• Reduction in total leaf area
• Choking of leaves
• Delay in flower initiation
• Reduction in yield and quality

Nutrient: Calcium (Ca)
Symptoms on leaf blades: Young leaves only: marginal chlorosis
Additional symptoms: 

• Thickening veins
• Deformation or absence of leaf lamina = spike leaf

Nutrient: Magnesium (Mg)
Symptoms on leaf blades: Young leaves only: pale green to yellow or white color; necrotic patches on leaf patches
Additional symptoms: 

• Thickening of secondary veins
• Bladeless leaves
• Stunted growth
• Small or choked bunches

Nutrient: Manganese (Mn)
Symptoms on leaf blades:

• Old leaves only: dirty yellow-green color; narrow green edge at leaf margins,spreading along main veins towards midrib while interveinal areas remain green = comb-tooth appearance
• Blue petioles
• Irregular chlorosis of the leaves followed by necrosis
• Marginal blackening of the leaves followed by necrosis

Additional symptoms: Magnesium and potassium deficiency 

Nutrient: Iron (Fe) 
Symptoms on leaf blades:

• Young leaves only: yellow to white colorYoung leaves only: yellow to white color
•  Marginal blackening of the leaves followed by necrosis

Additional symptoms: 

Nutrient: Zinc (Zn)
Symptoms on leaf blades: Young leaves only: yellow stripes along veins; large bronze, pinkish or whitish chlorotic bands; reddish color on lower side
Additional symptoms: 

• Young leaves smaller in size, more lanceolate in shape
• Unfurled leaf alternating chlorotic and green  bands Fruit light green, twisted, short and thin

Nutrient: Natrium (Na)
Symptoms on leaf blades: Marginal chlorosis of the leaves followed by necrosis
Additional symptoms: 

Nutrient: Chlorine (Cl)
Symptoms on leaf blades: 
Additional symptoms: Fruits not filled

Nutrient: Boron
Symptoms on leaf blades: Marginal chlorosis of the leaves followed by necrosis
Additional symptoms: 

Nutrient: Copper (Cu)
Symptoms on leaf blades: 
Additional symptoms: Root growth inhibited