Towards a healthy banana TC industry

Thomas Dubois,

Tissue culture banana
Banana in smallholder farmer systems is traditionally propagated by means of suckers. These contain soil-borne pests and diseases, and by using them, farmers unknowingly distribute and perpetuate pest and disease problems.

Plants produced by tissue culture (TC), because they are produced axenically in the laboratory, are material that is free from pests and diseases with the exception of fastidious bacteria and viruses.

Young tissue culture plantation in Nairobi, Kenya. Photo by T. Dubois, IITA.
Young tissue culture plantation in Nairobi, Kenya. Photo by T. Dubois, IITA.

There are many added benefits to using TC plants: (1) they are more vigorous, allowing for faster and superior yields; (2) more uniform, allowing for better marketing; and (3) can be produced in huge quantities in short periods of time, allowing for faster and better distribution of existing and new cultivars, including genetically modified banana. In other words, the TC technology can help banana farmers to make the transition from subsistence to income generation.

However, TC plantlets are relatively fragile and require appropriate management practices to fully harness their potential, especially during the initial growth stages shortly after being transplanted to the field. In East Africa, TC plantlets are often planted in fields burdened with biotic pest pressures and abiotic constraints.

A SWOT analysis
The importance of the private sector
The adoption of TC technology is still relatively low in East Africa. In Kenya, coverage of TC banana is estimated at 5–7% of the total banana acreage; adoption rates are significantly lower in countries such as Uganda, Burundi, and Tanzania, although reliable data do not exist.

Cumulative yield (t/ha/cycle) of a plantation derived from tissue culture (orange bars) compared to one derived from conventional planting material (blue bars), over 5 cropping cycles under two management regimes (low input and high input). Every little block represents one crop cycle. Data based on 1,600 plants total.
Cumulative yield (t/ha/cycle) of a plantation derived from tissue culture (orange bars) compared to one derived from conventional planting material (blue bars), over 5 cropping cycles under two management regimes (low input and high input). Every little block represents one crop cycle. Data based on 1,600 plants total.

In East Africa, the technology is booming under the impetus from the private sector. At least 10 commercial private laboratories have sprung up in the last decade in Burundi, Kenya, Uganda, and Tanzania. Collectively, they produce at least 2 million plants/year, although exact numbers seem to fluctuate widely and are hard to come by. Most of these companies manage the entire production chain, from sourcing the mother plants to weaning the TC plantlets. Despite the steep entry barrier, the TC business is very lucrative for the entrepreneur who engages in plantlet production. In some countries, universities and research organizations are also involved in the commercial production of TC banana.

Lack of quality standards and virus indexing
One of the biggest dangers for sustainable commercial production of TC plants is the lack of several essentials: (1) standards for quality management during the production process, (2) plant health certification, and (3) regulatory procedures. Such conditions are especially important to avoid spread of viruses, which are easily transmitted through TC plantlets.

For instance, Banana bunchy top virus (BBTV) is on the list of the 100 most dangerous invasive species worldwide. It is widely distributed in Central Africa and also in Burundi and Rwanda in East Africa, yet implementation of virus indexing schemes is largely absent in East Africa. It is important to put in place standard procedures for ensuring the production and distribution of high-quality, virus-free planting material, and to establish independent agencies that set and implement standards and improve the skills of personnel. In East Africa, certification schemes need to be regionally harmonized, especially with the transnational movement of plants between the countries, so that there is no weak link in the region.

Unregulation—a potential danger to the spread of diseases
At present, the commercial production of TC banana plantlets is largely unregulated. Not only are TC banana plantlets being moved in very large quantities across borders; uncertified mother material is also crossing borders. This practice is potentially risky, and could perpetuate infected sources and cause new outbreaks of disease.

In the ideal situation, there need to be certification standards for the quality and health of TC plants and the monitoring of TC producer operations. These are largely ignored because of poor awareness, and the lack of capacity and regulations required for the implementation of such standards. To transform the system, governments and/or the TC industry could consider common facilities to implement certification schemes. For instance, an accredited governmental or independent virus indexing laboratory, established as a commercial service for TC operators, would leverage costs and improve TC standards.

Another important requirement for TC producers is sustainable access to virus-free and true-to-type mother plants and this is currently lacking. The establishment of certified mother plant gardens as a common resource, either by governmental agencies or a consortium of commercial TC producers, would provide this essential requirement.


Contrary to a general perception, especially among donors, it is not merely the standards themselves that are a constraint, but also a lack of knowledge on how procedures are actually implemented along the value chain, through certification schemes. The equipment for virus indexing has become relatively cheap and technical skills are quite easily acquired. Their costs can be offset, e.g., through a service-based fee to private sector stakeholders.

Also, emphasis could equally be placed on certifying general operational procedures in a private TC laboratory. Currently, the quality of TC plantlets varies significantly, and several producers are struggling with off-types and accidental mixtures of varieties that become apparent only after being planted in the field, resulting in negative perceptions about TC.

Certification schemes need to be implemented in such a way that they do not become burdensome to producers or create bureaucratic barriers. Several quality certification schemes used for clonal crops, including banana, from other regions can be considered to develop an appropriate scheme for East Africa. Ultimately, it is not only the commercial sector that should self-regulate; governmental bodies need to take responsibility.

Nurseries for TC plants are essential, as they act as a distribution hub connecting producers to the farmers. They also act as focus centers for farmers and farmers’ groups, and are therefore an easily approachable venue for training and other interventions. The survey by IITA and University of Hohenheim of all TC nurseries in Burundi, Kenya, and Uganda, found that nurseries in East Africa face an array of problems. Relationships between producers and nurseries, especially those related to timing, quality, and quantity of plantlet supply, are often suboptimal.

At the nursery level, there are three main operational issues: access to water, credit, and the transport of plantlets. The location of the nurseries is also crucial. Nurseries need to be close to the producer and to the market, otherwise they might fail. Clear drivers for the success of a nursery are good agricultural practices and, interestingly, a diversification into crops outside banana.

Plantain for sale in market. Photo by IITA.
Plantain for sale in market. Photo by IITA.

In TC banana value chains, nurseries have different roles across countries in East Africa. In Uganda, nurseries are run as businesses independent of the TC operators and of the farmers. In Burundi, the nurseries are owned and managed by the producers. In Kenya, nurseries are run as entities separate from the producers, and most of them are owned by farmers’ groups that act as the customers for these nurseries. The business model in Kenya seems to hold the secret for a sustainable and vigorous link between producers and farmers.

Distorted value chains
One danger for a healthy commercial TC sector is the lack of sustainable market pathways to deliver the plants to the farmers. Especially in Burundi and Uganda, outlet markets for TC plantlets are mainly governmental and nongovernmental organizations, a situation which seems unsustainable in the long term.

The sustainability of the banana TC industry is especially worrisome in Burundi, where the entire value chain is subsidized. Virtually all TC plantlets are being bought by developmental agencies, which then pass on these plantlets to often untrained farmers, free of charge, and without embedding this transfer in an encompassing training program or input package (e.g., fertilizers).

Empowerment of farmers in the value chain through farmers’ groups
Organizing banana farmers into groups has long been considered advantageous, because of increased buying and selling power, reduced economic and social risk, increased economies of scale, and improved access to credit and inputs by formally certified groups.

The study by IITA and the University of Hohenheim of the farmer-to-market linkage in Uganda demonstrated that farmers in marketing groups obtain higher prices than their ungrouped colleagues. The certification of farmers’ groups implemented by IITA’s national partners, ISABU (L’Institut des Sciences Agronomiques du Burundi) in Burundi and VEDCO (Volunteer Efforts and Development Concerns) in Uganda, has made them eligible for savings and credit schemes. Some have even engaged in other commercial activities, such as the start-up of a catering service.

The importance of a training package
In East Africa, the distribution of superior planting material alone will not ensure a good crop. Commercial farmers are skilled in juggling the inputs and effort needed to produce crops and make a profit but smallholder farmers are constrained by factors such as a lack of land and capital, access to technology, and a good marketing infrastructure. Therefore, efficient distribution systems will be needed to deliver the TC plants as part of a package, including training and access to microcredit.

Training of farmers' group on business skills in Uganda. Photo by M. Lule.
Training of farmers' group on business skills in Uganda. Photo by M. Lule.

IITA and its national partners, ISABU, JKUAT (Jomo Kenyatta University of Agriculture and Technology), and VEDCO, have been implementing hands-on, comprehensive training schemes for farmers as well as the operators of TC banana nurseries. Training schemes encompass modules in agronomy, marketing, business and financing, and for farmers, group formation and group dynamics. Participants were followed for over a year, and their ability to implement the skills learned during the training program was monitored. So far, a total of 851 separate training events have been implemented in Burundi, Kenya, and Uganda, and through the partnership, 10 new farmers’ groups and 5 new nurseries have been established.

Location, location, location
TC banana plantlets come at a cost, and might not be economically beneficial throughout all banana-producing areas in East Africa. Location is everything.

IITA, in collaboration with Makerere University, conducted a cost-benefit analysis of the technology based on a comprehensive quantitative questionnaire with 240 farmers across four districts in Uganda, and compared it with the use of conventional planting material.

Gross margins (in Ugandan shillings)/ha/year of banana plantations derived from tissue culture (yellow bars) compared to conventional planting material (orange bars) in Uganda, the further away from the main banana market.
Gross margins (in Ugandan shillings)/ha/year of banana plantations derived from tissue culture (yellow bars) compared to conventional planting material (orange bars) in Uganda, the further away from the main banana market.

Both production costs and revenues were consistently higher for TC-derived material than for suckers. However, banana prices varied greatly with district and declined significantly with increasing distance from the main market (see graph). Also, production costs decreased significantly the further away the farms were from Kampala due to better agroecological conditions and the much reduced pressure from pests and diseases. As a result, although both TC plantlets and suckers were profitable to the farmer, TC material was more profitable than suckers closer to the main banana market.

In districts with low banana prices and at a greater distance from the main banana market, farmers could receive similar gains by planting suckers rather than TC plants. For a farmer in Uganda, it makes economical sense to grow TC banana close to the main urban market.

An objective ex-post assessment
Despite a booming commercial sector, there is only anecdotal evidence that farmers who have adopted TC banana benefit tremendously in terms of higher yields and household incomes. Sound socioeconomic analyses are crucial to guide policy strategies, learn from successes already achieved, and identify important constraints for a wider dissemination of TC banana in the region.

Earlier studies on the impacts of TC banana in the region have either employed ex ante methods before any meaningful adoption was actually observable, or they have used relatively simple and ad hoc qualitative methodological tools, which do not allow robust and representative statements. The large body of subjective ‘gray’ literature, sometimes unconditionally and unilaterally promoting the benefits of TC banana, without considering the quality of the plant material, input package, and market access, risks having an adverse effect on the adoption of the technology in the long term.

Banana market in Ikire, Nigeria. Photo by O. Adebayo, IITA.
Banana market in Ikire, Nigeria. Photo by O. Adebayo, IITA.

The University of Göttingen, in collaboration with IITA, is currently answering the following main research questions: (1) What are the determinants of TC banana adoption among farmers? (2) What are the impacts of this technology on on-farm productivity, household income and income distribution, and poverty and food security? (3) How do institutional factors in technology delivery and product marketing influence adoption and impact?

Some of these research questions have been answered. In Kenya, a substantial share of the population has heard about TC banana and is, therefore, generally aware of the technology’s existence, although only a few have had a chance to fully understand its performance and requirements. This study finds that farmers’ education, access to agricultural information, knowledge of the location of a TC nursery within a reasonable distance, and affiliation to social groups significantly increase the likelihood of the TC technology being adopted.

This study also highlights the positive role of access to credit and of gender in the adoption of TC material. Farmers with access to credit and female-headed households are more likely to adopt TC plants. The latter finding is particularly interesting from a policy perspective, because it shows that, when there is an equal chance for both men and women to acquire sufficient knowledge about an innovation, women are more likely to adopt it.

Tackling the banana menace

Lava Kumar,, and Rachid Hanna,

Banana bunchy top disease (BBTD) is emerging as a serious threat to banana and plantain production in several regions in West-Central and Southern Africa. IITA is undertaking research to understand the factors leading to the increase in BBTD incidence and spread with the ultimate goal of developing integrated strategies to protect bananas from this menace.

BBTV-infected plants in field. Photo by L. Kumar, IITA
BBTV-infected plants in field. Photo by L. Kumar, IITA
The livelihoods of over 70 million people are intimately linked to banana (banana and plantain), a major food staple and premier fruit. It occupies an important position in the agricultural economies in sub-Saharan Africa (SSA). Banana plantations produce fruits all year round, providing farmers with food and income, even during fallow seasons, thus contributing to food security.

Various types of banana are grown in SSA: plantain in the humid lowlands of West and Central Africa; highland cooking banana in East Africa; and introduced dessert banana in all the subregions.
The world’s greatest variability in the crops is held in West and Central Africa for plantain and Great Lakes Zone in Eastern Africa for highland banana. These regions are considered as secondary centers of banana diversity.

The foe
Bunchy top disease caused by banana bunchy top virus (BBTV) is emerging as a serious threat in several regions in Central and Southern Africa. This disease, first reported from Fiji in 1889, has been dubbed as one of the most destructive plant viral diseases. BBTV has been found in Asia, Africa, Australia, and the South Pacific islands. It belongs to the genus Babuvirus of the family Nanoviridae. The virus readily spreads in vegetative material such as corms and suckers. It also relies on the banana aphid, Pentalonia nigronervosa, its sole biological vector.

Banana with typical bunchy top disease symptoms. Photo by L. Kumar
Banana with typical bunchy top disease symptoms. Photo by L. Kumar
BBTV curtails plant growth, resulting in unproductive plants. Leaves of infected plants have pale chlorotic margins, dark green dots, and streaks along the veins which often extend down the midrib and petiole. Emerging leaves become progressively smaller and choked in the throat of the plant creating the “bunchy” appearance at the top.

Plants infected at an early age rarely produce fruit and eventually die. Those infected at a later growth stage may produce bunches, often with deformed fruits, but suckers have typical symptoms and remain unproductive. Due to the high destructive potential of BBTV on biological diversity and human activities, the Invasive Species Specialist Group (ISSG) of the World Conservation Union (IUCN) included BBTV in the list of 100 of the World’s Worst Invasive Alien Species.

Formidable challenges
Usually viral diseases are effectively controlled through the use of resistant sources. So far, banana varieties resistant to BBTV have not been found. Some types are tolerant or express symptoms relatively slowly. Eradication and exclusion are the only options found to be effective in controlling BBTV. These phytosanitary approaches rely heavily on early detection and destruction of the diseased mats, coupled with strict quarantine and indexing procedures to prevent further spread.

For instance, in Australia, strict legislation prevents the transfer of plant material from infected to uninfected areas. Skilled workers conduct regular inspection to identify and destroy any plant displaying disease symptoms. Thus, disease incidence has been kept at a very low level.

However, rigorous enforcement of phytosanitary procedures is expensive and extremely difficult to implement in SSA where socioeconomic conditions are poor and capacity is inadequate. In addition, banana cultivation is mainly carried out by subsistence farmers and large areas occur in the wild. Under these conditions, eradication is very difficult and this can affect livelihoods of the farmers. More research is necessary to devise control strategies that are congenial for application in SSA.

Distribution map of BBTV and the banana aphid in Africa. Map by IITA
Distribution map of BBTV and the banana aphid in Africa. Map by IITA
BBTV distribution in Africa
In Africa, the virus was first reported from Egypt over a century ago. In the 1950s, it was reported from Central Africa. The origin of this virus is not clear, but it may have been introduced into Africa through infected suckers brought by migrants from South Asia. Subsequent spread might have occurred from the movement of infected suckers by humans and natural spread by the vector aphids.

Despite its presence for at least five decades, the disease attracted very little attention until its recognition in the mid-1990s in Burundi, Malawi, and Rwanda where it was causing serious epidemics.

Our surveys from 180 sites in West, Central and Southern Africa point to 1994-1996 as the years when there was widespread appearance of the disease.

Presently, BBTV has been identified in Angola, Burundi, Cameroon, Congo, DR Congo, Equatorial Guinea, Gabon, Malawi, Mozambique, Rwanda, and Zambia.

Banana aphid and biocontrol
The banana aphid is widespread in SSA. Considerable variations in abundance were observed in our studies depending on locality, banana variety, and season. The aphid is likely to be responsible for much of the local spread of the disease and to some extent its long distance transport. Unlike annual crops, where the fallow period acts as a check for vectors, the perennial nature of banana allows aphids to survive all year round, aiding virus spread.

Aphid control will play a significant role in BBTD management.

Banana aphids are found between the whorls of the pseudostem and newly emerged leaves. Photo by L. Kumar
Banana aphids are found between the whorls of the pseudostem and newly emerged leaves. Photo by L. Kumar
The banana aphid is exotic to Africa and lacks indigenous natural enemies. Classical biological control is being explored that includes testing known natural enemies and exploration for new ones for introduction into Africa. IITA has successfully used this approach to control several exotic pests. Biological control could minimize the local spread of the disease, and perhaps reduce it to very low levels, when coupled with tolerant varieties.

At present, BBTV spread is not controlled in SSA. Besides its effect on food security, the virus poses a serious threat to the diversity of plantain and highland banana.

Understanding its disease ecology, demographics of distribution, vector biology and ecology, awareness creation, and conventional and nonconventional approaches to tackle the virus and vector is expected to provide a reprieve in the medium term and sustainable solutions in the long term.