Agricultural biostimulants for banana that won't start: guide

Banana stagnation: initial causes of failure to establish

Banana is a demanding crop in terms of water, soil aeration and nutrition, and when any of these factors fails the plantation can stall. Growers speak of failure to establish or stagnation when, after a reasonable time from planting or from the start of a new cycle, the plants do not produce vigorous new leaves, the pseudostem does not thicken and the suckers take time to appear. Despite irrigation and fertilisation, the crop appears halted, and the temptation is to look for a product that will "wake it up".

In practice, there is rarely a single cause. It is usual for several factors to combine: low-vigour planting material, poorly settled planting, compacted or waterlogged soil, irrigation water with salts, unbalanced nutrition or some soil organism that damages the root. This is why agricultural biostimulants should be understood as one more tool within a complete management programme, and not as an isolated solution. This guide explains what to check, in what order, and what role these products can play.

When the banana fails to establish, the first reaction is usually to increase fertilisation. It is worth pausing before doing so: if the root is not working well, more fertiliser does not translate into more uptake and may add salts precisely where the root is most sensitive. The sensible approach is to understand first what is happening beneath the plant.

Causes worth reviewing

• Planting material: the sanitary quality and vigour of the starting plant or sucker condition everything that follows.
• Planting: corm depth, contact with the soil, compaction in the planting hole and acclimatisation of the young plant.
• Water: insufficient or excessive irrigation after planting, poor distribution and water quality, including its salinity.
• Soil: compaction, poor drainage, inadequate pH, low organic matter or imbalances between nutrients.
• Climate and environment: low temperatures, wind or intense sun on young plants that are not yet established.
• Competition: weeds very close to the plant, competing for water and nutrients during the establishment phase.
• Biotic causes: nematodes, soil fungi or insects that damage the corm and the root; these require a specific diagnosis.
• Management: excess salts from fertilisation, poorly designed product mixes or misplaced applications.

Each of these causes is corrected in a different way. A biostimulant does not replace diagnosis, and applying it without knowing what is wrong can delay the real solution and add a cost that contributes nothing.

The role of the root in banana establishment

The banana root is fleshy, light in colour and fragile. It emerges from the corm and extends mainly horizontally, in the surface layers of the soil. It serves two functions: it anchors the plant and it is the pathway through which water and nutrients enter. Its development depends on the soil being well aerated, on moisture being regular, on temperature being adequate and on nutrient supply being balanced, including elements such as calcium and boron.

Being so close to the surface, the root responds poorly to compaction, waterlogging, salinity and lack of oxygen. A compacted soil limits penetration; a saturated soil hinders gas exchange; a soil with excess salts can prevent the plant from taking up water even when it is moist. When the root is not working, it shows in the aerial part: small new leaves, a thin pseudostem and few suckers.

That is why, when growth stalls, the first step is to dig and observe the roots. Light-coloured, firm roots with active tips indicate a different situation from that suggested by dark, soft roots or roots with lesions. That observation is a better guide than any general recipe as to whether the problem is physical, chemical or biological.

Factors affecting root growth

• Soil compaction: hardened layers slow root penetration and limit aeration; it is usually caused by machinery traffic or by heavy soils worked when too wet.
• Waterlogging: the lack of oxygen in the root zone damages tissues and encourages rots.
• Salinity: salts in the soil or in the irrigation water hinder water uptake and can damage the root and the leaves.
• Calcium and boron: nutritional imbalances can hinder the development of root tips; soil analysis and leaf analysis help to detect them.
• Soil organisms: nematodes and fungi can damage the root; their presence is confirmed by laboratory analysis or by assessment by a technician.
• Low organic matter: soils poor in organic matter retain water less well and have less biological activity.

An illustrative and purely hypothetical example: imagine a plot where young plants stall even though they receive complete fertilisation. On opening a test pit, a hardened layer is observed at shallow depth that the roots cannot penetrate. In such a situation, the priority is to resolve the compaction and drainage; any product applied afterwards will only make sense as a complement to that correction.

How to diagnose the problem before applying anything

A good diagnosis avoids unnecessary applications and helps to order decisions. A simple working order can be as follows.

• Observe the pattern: does it affect the whole plot, specific areas or isolated plants? A patchy pattern usually points to the soil, drainage or a biotic hotspot; a uniform pattern points more towards management, water or plant material.
• Dig and inspect: roots, corm, planting depth, abnormal odours, galleries or lesions.
• Analyse: soil (texture, pH, electrical conductivity, organic matter and nutrients), irrigation water and, where appropriate, leaf tissue. It is advisable to use a trusted laboratory and a technician who knows how to interpret the analyses.
• Review irrigation: amount, frequency, uniformity and water quality, as well as the condition of emitters and filters.
• Go over the history: previous crop, amendments, fertilisation and products applied, and any mixtures that have been made.
• Consult a technician: if nematodes or fungi are suspected, confirmation and measures are defined by a professional with authorised products.

Signs, possible causes and what to check

Sign observed	Possible causes	What to check
Small new leaves and thin pseudostem	Poorly functioning root, compaction, lack of water or nutrients	Dig and observe the roots; soil analysis; review irrigation
Plants stalled only in areas of the plot	Poor drainage, compacted layer, hotspot of soil organisms	Plot map, soil pits and laboratory diagnosis
Dry leaf edges and halted growth despite irrigation	Excess salts in the soil or in the water	Electrical conductivity of the soil and of the irrigation water
Dark, soft roots or roots with lesions	Lack of oxygen, waterlogging or soil organisms	Plot drainage and sample for laboratory
Recently planted plant that does not emit leaves	Weak plant material, inadequate planting or poor establishment irrigation	Origin of the material, planting depth and contact of the corm with the soil

The table is indicative: several signs may coincide in the same plot and the same sign may have more than one cause. The more refined the diagnosis, the easier it is to decide whether a product is needed and which one.

Agricultural biostimulants in the management of stalled banana plants

Agricultural biostimulants are products applied to the plant or to the root zone for the purpose of favouring crop processes, such as nutrient utilisation or stress tolerance, regardless of the nutrient content of the product itself. Regulation (EU) 2019/1009, applicable since July 2022, regulates plant biostimulants within EU fertilising products. They do not replace fertilisation and are not a plant protection treatment: at best, they can contribute to the general vigour of the crop when the rest of the management is correct.

Products with seaweed extracts, amino acids and peptides, humic and fulvic substances or microorganisms are found on the market. What each product declares about its composition and its purpose appears on the label and in the manufacturer's documentation; that information, and not the general category, is the reference for deciding.

The role usually assigned to them

Products with seaweed extracts or amino acids are usually proposed as support for vegetative development and for crop recovery after a stress situation. Those containing humic and fulvic substances are associated with soil and root zone management. Those incorporating microorganisms, such as mycorrhizae or soil bacteria, depend on the soil conditions and the other applications allowing their establishment, and their compatibility with other products must be checked before mixing.

The response of a stalled crop to a biostimulant is variable. If the problem is compaction, waterlogging, excess salts or a soil organism, the product does not correct the cause. That is why it is proposed as a complement to cultivation practices and irrigation, and not as a substitute for them.

How to choose and apply a biostimulant

• Define the cause: choose the product on the basis of the diagnosis and a clear objective, not the other way round.
• Read the label: composition, declared purpose, crops and indicated uses. Doses, water volumes, frequency and timing of application are set according to the product label.
• Request the documentation: technical data sheet, manufacturer's declaration and, if the product is marketed as an EU fertilising product, the corresponding labelling information.
• Check compatibility: before mixing with fertilisers or other products, carry out a test in a small volume and consult the manufacturer, especially if the product contains microorganisms.
• Choose the route: to the soil, with irrigation or as a foliar application, as indicated on the label and according to the condition of the plants. Avoid the hours of maximum sunshine and ensure the soil has adequate moisture.
• Record what you do: date, product, method of application and condition of the plants, so that the response can be assessed on a sound basis.
• In organic production: confirm with the certification body that the product is admissible before using it.

There is no dosing guideline or calendar that works for all cases: they depend on the product, the phenological stage of the plants and the area and the season. Any recommendation that promises a universal dose or timescale should be questioned.

Another illustrative example, equally hypothetical: on a plot with little organic matter, where compaction and drainage have already been corrected, a technician could propose a biostimulant as support during root regrowth. If after a reasonable time there is no response, the sensible thing is to return to the diagnosis instead of repeating the product.

Agronomic management of the soil and the root

For any application to make sense, the physical and chemical limitations of the soil must first be corrected. Compaction is a frequent problem in clay soils or where machinery traffic occurs. If it is confirmed, a technician can recommend subsoiling or scarifying at the appropriate depth for each plot, working the soil when it has a moisture level that allows the hard layers to be broken without destroying its structure.

Organic matter improves porosity and water retention capacity. It can be supplied in the form of compost or well-rotted manure, in the quantity indicated by the analysis and the needs of the soil. In organic production, the type and origin of the amendment must be confirmed with the certification body.

pH and nutrient balance also have an influence. A very acidic or very alkaline soil alters the availability of various elements and can harm the root. Corrections are planned on the basis of an analysis and with technical advice and, in organic farming, only with amendments accepted by the certification body.

Irrigation management is another pillar. It is important to maintain regular moisture, avoiding both drought and waterlogging, and to adjust it to the type of soil, the climate and the crop stage. Moisture sensors and tensiometers help to schedule irrigation on a sound basis. If the soil is dry at depth but saturated at the surface, there is an infiltration problem that is resolved through soil structure and water management rather than through any application. It is also advisable to analyse the irrigation water: if it contains salts, it may be necessary to adjust the frequency and volume to prevent them from accumulating in the root zone.

Finally, weed control and the maintenance of adequate soil cover limit competition during establishment and help to protect the soil surface against compaction caused by irrigation or rain.

When the cause may be biotic

Nematodes, soil fungi such as Fusarium or Rhizoctonia and insects that attack the corm are possible causes of stunting. These are problems that require confirmation by a laboratory or a technician, and biostimulants are not a plant protection treatment and must not be proposed as such.

If the diagnosis confirms a biotic cause, it will be the adviser who defines the measures, which may include healthy plant material, hygiene of tools and machinery, water and soil management and, where appropriate, products authorised for that use. Some banana diseases are subject to official plant health regulations, so, if suspected, the competent plant health services should be notified.

What to expect and how to assess the response

The response of a stalled plantation is neither immediate nor uniform, and there is no valid timeframe for all situations. It depends on the cause, the climate, the soil, the crop stage and how well the underlying problem has been resolved. What can be done is to observe specific signs: new roots when digging, leaves that emerge larger than the previous ones, thickening of the pseudostem and the appearance of suckers.

To assess the response honestly, it is advisable to leave a reference area within the plot itself, with similar conditions but without the measure being evaluated, and to record the dates and observations. Without that comparison it is easy to attribute to a product what is due to improved irrigation, a change in the weather or the simple natural recovery of the plant.

Biostimulants do not replace balanced fertilisation: they complement it. Combining fertilisation adjusted to the analysis, which in organic farming is confirmed with the certification body, with appropriate soil and irrigation management is the foundation on which a biostimulant can make sense.

The decision to incorporate a biostimulant also has an economic dimension. It is advisable to request a detailed quotation, assess the cost of the programme against the whole of the fertilisation and remember that resolving the underlying cause usually matters more than adding products. A well-managed soil allows inputs to be adjusted better over time.

When to rethink the plan

• No new roots are observed when checking the plants after a reasonable period: go back to the diagnosis.
• New symptoms appear or the plants worsen: consult a technician as soon as possible.
• The response is uneven within the plot: review the differences in soil, drainage and irrigation between areas.

Conclusion: start with the root and the soil

The failure of the banana to get going is a symptom that something is not working in the root, in the soil or in the management. Before increasing fertilisation or bringing in new products, it is necessary to diagnose and correct the physical, chemical and biological limitations. Agricultural biostimulants can contribute to the general vigour of the crop as a complement to good management, but they are not a plant health treatment and do not replace diagnosis, subsoiling, organic matter or efficient irrigation.

If your plantation is not getting going, you can contact the Ecoganic team to discuss the case, receive technical guidance and request a quote for the product that best fits your programme.