The International Journal on and Plantain

Spotlight on the banana congress Breeding better Cell death and disease resistance The roots’ health support system Soil fertility in East Africa Marketing partnerships How to contain bacterial wilt

Vol. 13 No.2 December 2004 InfoMusa

Cover photo: Vol. 13 No.2 Banana worker in northern Peru. (Anne Vézina, INIBAP) INFOMUSA Vol. 13, No. 2

Publisher: International Network for the Improvement of Banana and Plantain

Publishing director: Claudine Picq

Editor: Anne Vézina

Editorial Committee: Jean-Vincent Escalant, Richard Markham, Nicolas Roux, Charles Staver

Layout: Crayon & Cie Printed in France ISSN 1023-0076

Editorial Office: INFOMUSA, INIBAP, Parc Scientifique Agropolis II, 34397 Montpellier Cedex 5, France. Telephone + 33-(0)4 67 61 13 02; Telefax: + 33-(0)4 67 61 03 34; E-mail: [email protected] Contents Subscriptions are free for developing countries readers. Article contributions and letters to the editor are welcomed. A review of conventional improvement strategies for Articles accepted for publication may be Kodjo Tomekpe, Christophe Jenny and Jean-Vincent Escalant 2 edited for length and clarity. INFOMUSA is not responsible for unsolicited material, however, every effort will be made to Can model plants help banana improvement through biotechnology? respond to queries. Please allow three Martin B. Dickman 6 months for replies. Unless accompanied by a copyright notice, articles appearing in INFOMUSA may be quoted or reproduced Diseases and pests: A review of their importance and management without charge, provided acknowledgement Randy Ploetz 11 is given of the source. French-language and Spanish-language Population genetic structure and dispersal of Mycosphaerella fijiensis editions of INFOMUSA are also published. An electronic version is available at the Jean Carlier 17 following address: http://www.inibap.org/publications/infomusa/ Soil quality problems in East African banana systems and their relation infomusa_eng.htm To avoid missing issues of INFOMUSA, with other yield loss factors notify the editorial office at least six weeks in P.J.A. van Asten, C.S. Gold, S.H. Okech, S.V. Gaidashova, advance of a change of address. W.K. Tushemereirwe and D. De Waele 20 Views expressed in articles are those of the authors and do not necessarily New technologies to increase root health and crop production reflect those of INIBAP. Richard A. Sikora and Luis E. Pocasangre 25 Partnership and networking in the tropical fruit industry: the experience of the International Tropical Fruits Network Khairuddin Tahir 30 Focus on the Musa congress 32 Focus on bacterial wilt 38 The mission of the International Network for the Improvement of Banana and Plantain is Thesis 41 to sustainably increase the productivity of banana and plantain grown on smallholdings MusaNews 42 for domestic consumption and for local and export markets. INIBAP is a programme of the International Forum 46 Plant Genetic Resources Institute (IPGRI), a Future Harvest centre. In memory of Dr Maribona 48

InfoMusa - Vol. 13 - No.2 1 The banana congress up close Editorial

We are pleased to offer you a special issue of INFOMUSA focusing on the First International Congress on Musa held in Malaysia from 6 to 9 July 2004. Organized by INIBAP and the Malaysian Agricultural Research and Development Institute (MARDI), the congress brought together some 250 delegates from all over the world, and from disciplines as far apart as genomics and fruit marketing, to share discussions and experiences under the theme Harnessing research to improve livelihoods. In addition to seven of the eight keynote addresses presented at the Congress (the one by Charles Staver on Farmer learning and plantain management in Nicaragua will be published in the June 2005 issue), this issue also contains a summary of the four sessions in the Focus on section. By publishing the keynote addresses so soon after the Congress, rather than filing them away while we prepare a formal proceedings that would be partly out of date by the time it is published, one of our aims is to reach a larger audience in a timely manner. We realize it is not a complete rendering of the Congress (the abstracts of the oral presentations and posters are available on our website, www.inibap.org). However, using INFOMUSA not only makes it possible to draw attention to the topical questions raised during those four days, it also provides an outlet to continue the discussion in our Forum section. We are also interested in your reaction to the format of the articles. Although this issue may seem to depart from INFOMUSA’s usual offering of scientific articles, in many ways it is not so different from past instalments. In the first years of its existence, the articles published in INFOMUSA were written in a more informal style than the scientific articles we currently publish, in keeping with its mission to inform readers “of INIBAP’s activities and present findings of the network”. But as stated in the first issue, INFOMUSA was also meant to “report on Musa research and activities worldwide”. Inevitably, at first, many of the articles were commissioned to our partners, but as the magazine became better known, submissions from researchers came to dominate its contents. As we are discovering with our survey, some readers would like a return to the less formal, some would say less scientific, and more newsy INFOMUSA. Others, however, would like to see it become a peer-reviewed journal. There is still time to let us know what you think by filling in the questionnaire on our website. We will be bringing you the results in the next issue. We will end with a few apologies. After urging our would-be authors to avoid jargon in their manuscripts, we were taken to task by people who answered the survey and were stumped by the expressions “upstream” and “downstream” research and “open-access” journal. By upstream research we mean the research done to develop innovative concepts and technologies, as opposed to downstream research, which integrates technology and knowledge in projects that have practical implications for farmers. Open-access journals are those that use a funding model that does not charge readers or their institutions for access. We also wish to apologise for suggesting, in the previous issue of INFOMUSA, that black leaf streak disease, caused by Mycosphaerella fijiensis, is now present in . In the article “Evaluation of new banana hybrids against black leaf streak disease”, the disease against which the hybrids were evaluated was Sigatoka disease, caused by Mycosphaerella musicola. We regret the error. As far as we know, there has been no official record of black leaf streak disease in India. We are grateful to the vigilant readers who brought this to our attention. The editors

InfoMusa - Vol. 13 - No.2 1 Genetic improvement A review of conventional improvement strategies for Musa Kodjo Tomekpe, Christophe Jenny and Jean-Vincent Escalant

ost cultivated bananas are (EMBRAPA) works on bananas of the Pome triploids. Although triploidy confers and Silk sub-groups, which are highly prized M a certain vigour to the plant, it in that country. also contributes to the sterility that greatly limits the use of hybridization in banana The 3x/2x strategy improvement and constitutes a challenge Two factors were decisive in the development to conventional breeding methods. In spite of the 3x/2x strategy: the discovery of residual of these difficulties inherent in the banana female fertility in certain triploid crop, notable progress has been made on the one hand, and the observation of a over the last twenty years and it is not substantial proportion of tetraploids among unusual nowadays to find artificial hybrids their descendants on the other, due to the in various research stations, contributing to formation of unreduced triploid gametes that rural development, and even being grown on enable the conservation of the entire triploid family farms. genome. This strategy has been widely used This progress stems from several to try to create tetraploid hybrids resistant to conventional breeding programmes diseases and of good agronomic value by (Menendez and Shepherd 1975, Rowe pollinating susceptible triploids with male and Rosales 1992, Shepherd 1968, Soares fertile diploids that are resistant. Filho et al. 1992, Swennen and Vuylsteke The best-known examples of dessert 1990, Bakry and Horry 1992, Jenny et al. hybrid tetraploids from FHIA arose from 1994, Tomekpé et al. 1998). In Honduras, crosses between dwarf mutants of ‘Gros the Fundación Hondurena de Investigación Michel’ and ‘Prata’ and improved diploids Agricola (FHIA) is the oldest existing resistant to black leaf streak and Sigatoka programme and works on several dessert and diseases, and to the nematode Radopholus cooking bananas. It is the only programme similis. As to cooking bananas, one can to improve the ‘Gros Michel’ dessert banana. distinguish CRBP-39 from CARBAP and The FHIA has developed various types FHIA-21 (plantain hybrids) and BITA 3 from of hybrids, some of which are currently IITA (a hybrid) all of which being distributed in several countries. In are resistant to black leaf streak and are France and in Guadeloupe, the Centre de currently being adopted by, or are already coopération internationale en recherche grown in, certain countries (Figure 1). agronomique pour le développement It should however be noted that nearly (Cirad) has concentrated for some twenty all the AAAB hybrids (resulting from years on the creation of new triploid dessert crosses between an AAB and an AA) can bananas for export, using a simple and show symptoms of banana streak disease original scheme based on a knowledge caused by the activation of viral sequences and exploitation of the existing diversity in integrated in the B genome of these cultivars. diploid dessert varieties (Bakry et al. 1997). Furthermore, the low fertility of the rare fertile In Nigeria, Cameroon and Uganda, the cultivars means that only small populations International Institute of Tropical Agriculture can be generated, and a considerable (IITA) has been breeding plantains for about number of crosses have to made to have twenty years, and more recently has been a chance of useful results. Another problem engaged in improving East African highland is the high water content in tetraploid fruit, bananas. In Cameroon, the Centre africain which ripen and soften rapidly. de recherches sur bananiers et plantains Moreover, hybrid tetraploids, AAAB as (CARBAP, ex-CRBP) has specialized for well as AAAA and AABB, often inherit male about the last twelve years on improving and female fertility from the fertile diploid plantains, of which it possesses the largest parent. Consequently they are liable to collection in the world. In Brazil, the Empresa produce bananas containing seeds if they Brasileira de Pesquisa Agropecuaria are pollinated, which obviously reduces

2 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 3 Figure 1. Tetraploids resistant to black leaf streak. Left to right, FHIA-21 produced by FHIA, CRBP 39 produced by CARBAP and Bita 3 produced by IITA. From left to right: FHIA, CARBAP and IITA

their quality. Removing the flowers avoids Mycosphaerella and to Fusarium wilt), bred unwanted pollination. One must also bear in the fifties by the improvement programme in mind that the 3x/2x strategy also enables of the former Jamaican Banana Board, and numerous types of AA diploid hybrids to the elite diploids developed by FHIA, some be created. More than 50% of the hybrids of which have multiple resistance (to leaf generated by certain plantains are AA spot diseases, nematodes and Fusarium diploids. wilt) and markedly longer fruit than the small Improvement of diploids fruit of wild diploids (Figure 2). Moreover, numerous monospecific AA and interspecific Unlike triploids, diploids are very fertile and AB diploid hybrids have been created by contain considerable genetic diversity; they the National Research Centre on Banana may be wild, semi-wild or parthenocarpic, (NRCB) and the Tamil Nadu Agricultural often with one or more sources of resistance University, in India. (or tolerance) to diseases and pests, More recent is the use of fertile diploid AA together with various organoleptic qualities. hybrids as parents or as starting material They have various levels of heterozygosity for developing elite diploids. In particular, and some of them are the ancestors of the these are plantain hybrids resistant to leaf triploid cultivars that need to be improved. spot diseases and with a fruit quality similar They are therefore good parents and ideal to that of plantains. This approach is used material for the genetic and cytogenetic especially by CARBAP and IITA to develop studies needed for optimizing the genetic diploids specific to certain sub-groups such improvement of bananas. Figure 2. Natural and improved diploids bred as plantains and the East African highland After intensely using wild diploids, by FHIA. Left to right, 3362, 3142, PJB, 3437, bananas. 2989, C-IV, 2095 and Lidi. breeders came to the conclusion that the choice of the ‘resistant donor’ should also take into account its agronomic characteristics and, if possible, certain features of fruit quality. Hence the introduction of strategies for developing improved diploids. The great genetic diversity of the diploids collected in and India has led to the selection of wild, semi- parthenocarpic and parthenocarpic diploids such as ‘Calcutta 4’ ( ssp. burmanicoïdes) and ‘Pisang lilin’ ( a fertile parthenocarpic diploid with seedless fruit). These have been used to improve triploid cultivars and have also provided the basis for developing improved diploid parents. Notable among these is M53 (resistant to the leaf spot diseases caused by

2 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 3 The 4x/2x strategy bananas based on their morphological and As part of the 4x/2x strategy, triploid hybrids molecular characters (Fauré et al. 1994, are created by hybridization of a diploid parent Jenny et al. 1999). The genetic variability with a tetraploid parent, previously obtained in the acuminata genome has been related by chromosome doubling of an ancestral to variability in fruit quality in the main cultivated groups. The most striking example diploid or an improved diploid hybrid using is probably the relationship between the colchicine (Figure 3). This strategy imitates subspecies Musa acuminata spp. banksii the natural process of banana evolution, and cooking bananas. As a result, cooking the natural triploid cultivars apparently triploid hybrids of purely acuminata origin having resulted from ancestral diploids by have been produced. The variability in the the accidental production of unreduced acuminata genome also makes it possible gametes in one of the diploid parents during to vary the type of fruit and plant, dessert hybridization (Simmonds 1962). The meiotic or cooking, but also the sugar content and error that resulted in these unreduced acidity, fruit length, degree of suckering and gametes is replaced in the 4x/2x strategy by yield etc. a chromosome doubling of one of the parents Among the first results obtained, by colchicine treatment (Bakry et al. 1997, CARBAP has identified, among the several Stover and Buddenhagen 1986, Vakili 1967). hundred individuals obtained from crossing The hybridization cannot continue since the BB x AAAA, (AAAA being susceptible and product obtained is almost completely sterile BB partially resistant to black leaf streak), and can therefore no longer be improved about 20% of hybrids showing useful using conventional methods. resistance to black leaf streak. Moreover, Unlike the 3x/2x strategy, the 4x/2x strategy by combining diploid plantain hybrids does not try to improve existing varieties but with cooking acuminata triploids obtained rather to create new improved varieties, at Cirad, CARBAP was able to obtain which closely approximate the objectives, populations of several hundred individuals, by using ancestral varieties. These hybrids among which several triploid AAA acuminata should therefore bring together all the hybrids resistant to black leaf streak are characteristics that are usually improved, undergoing the selection process. plus the improved characters for which the To sum up, this strategy offers unques- strategy was established. tionable advantages: a large number of This strategy, used in particular by available parents, better prediction of Cirad, has been made possible thanks heritability of valuable characters and to a better knowledge of the evolution of better fertility of diploid parents, resulting in larger populations, enabling the initiation of a real selection programme that can Tetraploid development even include several improvement criteria. AAw x AAcv colchicine Broadening the choice of diploid parents AAcv AAAAcv (1) AAcv x AAcv by developing an improvement strategy for colchicine diploids or by carrying out new exploration AAcv x BBw ABcv AABBcv (2) for material in the regions of interest could increase the potential of this strategy. In this Triploid development respect, CARBAP is currently developing AAcv x AAAAcv AAAcv AAw x AAAAcv AAAcv (3, 4) improved second- and third-generation diploids (secondary and tertiary diploids) BBw x AAAAcv AABcv (3, 5) from plantain diploid hybrids resistant to AAcv x AABBcv AABcv AAw x AABBcv AABcv black leaf streak by crossing diploid plantain hybrids with sources of resistance that are undergoing chromosome doubling. We note, however, that the AAB hybrids resulting from Figure 3. 4x/2x breeding scheme used by CIRAD and CARBAP. AAAA x BB crosses are also liable to suffer 1. Nealy 20 clones developed at CARBAP and CIRAD. from BSV. 2. Actually stopped because of BSV concern. In view of the problems associated with 3. Annual hybrid population size of nearly 400 plants in the field. 4. 98% of the progeny is triploid. the 3x/2x strategy and the fertility of the 5. Actually stopped because of BSV concern. tetraploids thus obtained, the latter were soon

4 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 5 regarded as intermediate products. Hence companies want resistant varieties that must they have been quite naturally crossed also comply with very precise pre- and post- with diploids to obtain triploids ‘genomically’ harvest management standards. This is one closer to the initial triploid cultivars, known of the reasons why the tetraploid dessert as primary triploids, while the triploids arising banana hybrids created by FHIA have not from 4x/2x crosses are called secondary been adopted by the . triploids. The 3x/2x strategy is in fact used in Greater progress could be made if this case as the only possible way to extract adequate resources were devoted to useful characteristics from the popular conventional breeding and if cooperation was triploid cultivars. This material is then better encouraged. Progress should also be made exploited on a larger scale using more in molecular studies to improve marker- fertile tetraploid and diploid hybrid parents assisted breeding. These studies should (F1 hybrids) capable of generating larger include the identification of resistance genes populations of F2 hybrids that are in fact the and also of those linked to abiotic stress grand-children of popular triploid cultivars. tolerance, parthenocarpy and fruit quality. However one should not lose sight of Many useful improvements can be made by the fact that the genetic gain obtained by conventional methods but the latter should nuclear restitution of the preceding stage be combined with unconventional techniques will be reduced by the recombination that under development such as mutagenesis, will occur during meiosis of the tetraploid. genetic transformation and even protoplast The choice of diploid parents for the F1 fusion. Only a comprehensive approach cross, and also for the F2 cross, is thus very can sustainably resolve all the problems that important and on it will depend the quality or the cultivars must confront. Moreover, one the reconstitution of the secondary triploid must not lose sight of the need to include hybrids. The latter should retain the desired the improvement strategies into a global characteristics of their grand-parents (the approach to sustainable management of the original triploid cultivars) to which should be banana crop, as improved varieties alone added characters of resistance to diseases cannot solve all the problems. and pests. This strategy has allowed IITA, EMBRAPA References and FHIA to obtain hybrid populations of Bakry F. & J.P.Horry. 1992. Tetraploid hybrids from sufficient size to make worthwhile selections interploid 3x/2x crosses in cooking bananas. Fruits 47:641-655. of good quality secondary triploid hybrids. Bakry F., F. Carreel, M.-L. Caruana, F.X. Côte, C. Jenny CARBAP also uses this approach to & H. Tézenas du Montcel. 1997. Les bananiers. Pp. generate large populations of secondary 109-140 in L’amélioration des plantes tropicales (A. triploid hybrids from primary tetraploids Charrier, M. Jacquot, S. Hamon et D. Nicolas, eds). derived from several rare dwarf plantain CIRAD and ORSTOM. bananas. The main advantage of this two- Fauré S., J.-L. Noyer, F. Carreel, J.P. Horry, F. Bakry & C. Lanaud. 1994. Maternal inheritance of chloroplast stage strategy is to obtain, via primary genome ant paternal inheritance of mitochondrial hybrids, several hundred second generation genome in bananas (Musa acuminata). Current descendants from very sterile triploid Genetics 25:265-269. cultivars. The example of dwarf-type triploid Jenny C., F. Carreel, K. Tomekpé, X. Perrier, C. Dubois, J.P. Horry & H. Tézenas du Montcel. 1999. Les hybrids obtained from primary tetraploid bananiers. Pp. 113-139 in Diversité génétique des hybrids that themselves arose from triploid plantes tropicales cultivées (P. Hamon, M. Seguin, X. cultivars of dwarf plantain bananas is worthy Perrier et J.C. Glaszmann, eds). CIRAD, Montpellier. of note. Menendez T. & K. Shepherd. 1975. Breeding new Kodjo Tomekpe works bananas. World crops May/June 104-112. at the Centre Africain de Conclusion Rowe P. & F. Rosales. 1992. Genetic improvement of Recherches sur Bananiers bananas, plantains and cooking bananas in FHIA, In spite of the difficulties inherent in the Honduras. Pp. 243-266 in Breeding bananas and et Plantains (CARBAP) in plant and the meagre resources devoted to plantains : proceedings of an International Symposium Cameroon, Christophe banana improvement, substantial progress on Genetic Improvement of Bananas for their Jenny at the Centre de has been made over the last twenty years, Resistance to Diseases and Pests (J. Ganry, ed.). coopération internationale en CIRAD-FLHOR, Montpellier, France. notably with bananas for local consumption, recherche agronomique pour Shepherd K. 1968. Banana breeding in the West Indies. i.e. those that are not sold by the big Pest articles and news summaries 14:370-379. le développement (Cirad), companies. Things are somewhat different Simmonds N.W. 1962. The evolution of the bananas. Guadeloupe and Jean-Vincent for dessert bananas for export: the big Longmans, Green & Co, London. Escalant at INIBAP, France

4 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 5 Soares Filho W., S. Dos, Z.J.M. Cordeiro, K. Shepherd, Swennen R. & D. Vuylsteke. 1990. Aspects of plantain J.L.L. Dantas, S. de Oliveira e Silva & M.A.P. da breeding at IITA. Pp. 252-266 in Sigatoka leaf spot Cunha. 1992. The banana genetic improvement disease: Proceedings of an international workshop programme at CNPMF/EMBRAPA, Brazil. Pp. 339-346 (R.A. Fullerton & R.H. Stover, eds). San José, Costa in Breeding bananas and plantains : proceedings of an Rica. International Symposium on Genetic Improvement of Tomekpé K., P. Rowe, H. Tezenas du Montcel & D. Vuylsteke. 1995. Plantain and Popoulou/Maia Maoli Bananas for their Resistance to Diseases and Pests (J. Breeding: current approaches and future opportunities. Ganry, ed.). CIRAD-FLHOR, Montpellier, France. Workshop INIBAP/MARDI, Serdang, Malaysia. Stover R.H. & I.W. Buddenhagen. 1986. Banana breeding: Vakili N.G. 1967. The experimental formation of polyploidy polyploidy, disease resistance and productivity. Fruits and its effect in the genus Musa. Amer. J. Bot. 54: 41:175-191. 24-36.

Genetic improvement Can model plants help banana improvement through biotechnology? Martin B. Dickman

ananas must cope with numerous (e.g. genetic transformation, gene silencing) environmental challenges, particu- are now possible in bananas (James Dale, Blarly with fungal and bacterial personal communication) and are mainly pathogens as well as pests and abiotic limited by the choice of gene(s). In other stresses. This situation is exacerbated by words, what do we insert? Moreover, while the limited diversity of cultivars. Moreover, the technology for gene manipulation has traditional breeding strategies are been available for a number of years for problematic due to a low female fertility, many plants, success under field conditions sterility, ploidy and poor seed set. As a result, has been hampered by our overall lack of classical genetics is difficult and limited, as understanding of the essential determinants well as being extremely time consuming. and pathways mediating stress/disease. Taken together, the difficulty in conventional However, thus more effective genes and beeeding, limited genetic diversity and poorly strategies are likely to ensue given the controlled diseases all point to the necessity availability of genome sequences. of developing alternative strategies for Model plants banana improvement. Biotechnological This section will discuss two model plants; approaches are particularly appropriate Arabidopsis and rice. Arabidopsis has for this crop. This review will focus on two served as an invaluable model plant in distinct, but overlapping issues: (i) the role numerous aspects of plant biology, including of model plants in providing avenues leading pathology and stress physiology, with many to approaches for banana improvement insights viewed to be directly applicable to through biotechnology and (ii) conceptual crop plants. In addition, Arabidopsis has approaches for generating bananas with a number of key experimental features: enhanced resistance to disease and other the genome is sequenced, microarray environmental stresses. chips are commercially available and a considerable number of mutants have been The attraction of genetic characterized. In addition, reverse genetics engineering will continue as a powerful tool to examine While the “track record” regarding gene function in Arabidopsis. successful applications of recombinant DNA However, Arabidopsis is a dicot and is approaches in generating transgenic plants not a crop plant. On the other hand, rice with enhanced agronomic traits (especially is both a monocot (and thus may be more involving disease resistance) is limited at closely related to banana) and a crop plant, best, it is also fair to say that this technology but is not so well genetically characterized, has considerable experimental power. It is although the complete sequence of the rice now evident that many important techniques genome will soon be available. Moreover,

6 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 7 many of the experimental features available Woffenden 2003, James Dale personal in Arabidopsis are being developed for rice; communication). Monocot R genes appear some of which are already in use (e.g. rice to be in the CC (coiled coil), NBS (nucleotide T-DNA knockout lines). The rice genome binding site) and LRR (leucine rich-repeat) is relatively small; about 3-4 times larger structure class as opposed to the TIR (toll-like than Arabidopsis (Resink and Buell 2004). inverted repeat) NBS LRR that predominates Moreover, a number of predicted genes in dicots, including Arabidopsis (for a review found in rice have homologs in Arabidopsis of R genes, see Martin et al. 2003). (Rice Chromosome 10 Sequencing Hulbert and colleagues recently described Consortium 2003). Another important an interesting approach for identifying consideration is the fact that rice, along novel sources of resistance (Zhao et al. with other closely related plants, exhibit a 2004 ). This group inoculated a number relatively high degree of synteny (Gale and of maize lines with the bacterium that Devos 1998). causes leaf streak of rice. Lines that Since banana genomics is in its infancy induced a hypersensitive response (HR) with limited sequence information, it is when challenged were identified. This premature to draw conclusions as to a phenotype suggests that these maize plants singular comparative strategy and to what were able to recognize the rice pathogen. degree synteny will be conserved. However, Following crosses, genetic control of the initial studies have been done (Aert et al. HR segregated as a single dominant locus, 2004). Interestingly, comparison of the suggesting the possibility of a single R banana genome structure and organization, gene. The responsible maize gene was derived from preliminary studies of BAC map-based cloned and, when inserted into end sequencing, with the ones of rice and rice, conferred resistance to the bacterial Arabidopsis suggested that banana may streak disease pathogen (S. Hulbert, actually be closer to Arabidopsis than to personal communication). This is more than rice (Chris Town, personal communication). just a demonstration, as this disease is very If this preliminary observation holds up, then severe in areas (e.g. China) where hybrid banana is positioned in a rather unique cultivars are extensively utilized and are place, a monocot with more affinity to dicots very susceptible to leaf streak. Moreover, than other monocots. these studies suggest that the same genes Gene transfer across species may be involved in non-host resistance and The Arabidopsis NPRI gene is a well- specific resistance. characterized central player in regulating systemic acquired resistance (SAR). When Programmed cell death overexpressed in Arabidopsis, enhanced Multicellular organisms eliminate disease resistance occurs. To evaluate unwanted, damaged or used cells by a the role of NPRI in monocot plants, the gene-directed programmed cell death Arabidopsis gene was overexpressed in (PCD) process. PCD is genetically rice and transgenic plants were challenged controlled cellular suicide and plays a with the rice bacterial blight pathogen critical role in a wide variety of normal Xanthromonas oryzae pv. oryzae. physiological processes. In humans Transgenic plants exhibited enhanced levels and other animals, dysregulation of this of resistance, although not as pronounced natural cell death pathway contributes as the resistant (Chern et al. 2001). greatly to diseases characterized by either These studies indicated that a dicot gene excessive cell accumulation (cancer, can be expressed and confer a useful autoimmune diseases) or inappropriate phenotype in a monocot and suggests that cell death (stroke, myocardial infarction, monocot and dicot plants share a conserved inflammation, AIDS, Alzheimer’s and other pathway that mediates resistance. neurodegenerative diseases). In addition, The identification and characterization most viruses and intracellular bacteria of major resistance genes (R genes) is an control the cell death pathway in the host important, active field of investigation, and cells they infect, thus linking apoptosis to banana is no exception ( McDowell and infectious diseases.

6 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 7 By far, the most common of the cell cells in embryos; (b) removal of unwanted suicide responses in animal species cells, such as the root cap cells found is “apoptosis”. Apoptosis refers to a in the tips of elongating plant roots and constellation of characteristic morphological the stamen primoridia cells in unisexual changes that animal cells typically undergo flowers; (c) deletion of cells during sculpting when dying by activation of the endogenous of the plant body and formation of leaf cell suicide program. The execution of lobes and perforations; (d) death of cells this program is often associated with during plant specialization, such as the cell shrinkage, membrane bleeding, death of tracheary element (TE) cells; and nuclear and cytoplasmic condensation, (e) leaf senescence (Dickman and Reed and DNA fragmentation. These DNA 2003). Regulation of cell death pathways fragments coalesce to form membrane- also occurs in response to abiotic stimuli bound apoptotic bodies that, in animals (Jones and Dangl 1996). In some cases, are rapidly phagocytosed and digested by cell suicide programmes are also activated macrophages. In this way, the dead cells during pathogen attack in both resistant are rapidly and cleanly removed and cellular and susceptible plant-pathogen interactions leakage of noxious and possible dangerous (Beers 1997, Mitsuhara et al. 1999). contents in avoided. Though the biochemical mechanisms In contrast, necrosis results from cellular responsible for cell suicide in plants are injury, cells swell and lyse, releasing largely unknown, a variety of reports cytoplasmic material, which in animals suggest similarities to the programmed often triggers an inflammatory response. cell death that occurs in animal species. While the distinction between these two For example PCD in plants typically forms of death is not always clear, in requires new gene expression, and thus necroses, the cell is not an active participant can be suppressed by cycloheximide in its demise. Apoptosis is usually also and similar inhibitors of protein or RNA associated with the activation of nucleases synthesis (Dickman and Reed 2003). The that degrade chromosomal DNA into small morphological characteristics of plant cells oligonucleosomal fragments, which when undergoing PCD also bear some striking electrophoresed, result in a characteristic similarities to apoptosis in animals, though “DNA ladder”. the presence of a cell wall around plant cells The genes that control programmed imposes certain differences. Akin to animal cell death are conserved across wide cells, PCD in plants is associated with evolutionary distances, defining a core set internucleosomal DNA fragmentation (DNA of biochemical reactions that are regulated ladders) and the activation of proteases in diverse ways by inputs from myriad (Ryerson and Heath, 1996, Solomon et al. upstream pathways. These genes encode 1999). either anti-apoptotic (e.g. Bcl-2, Bcl-xl, In addition to its role in developmental CED-9, IAP) or pro-apoptotic proteins (e.g. processes in plants, cell suicide plays an Bax, Bid, caspases), which do battle with important role in interactions of plants with each other in making life-death decisions for a variety of pathogens, including bacteria, fungi and viruses (Mittler and Lam 1996). the cell. Ectopic overexpression of certain One of the best studied of these plant types of anti-apoptotic genes can render responses to pathogens is the hypersensitive animal cells markedly resistant to a wide response (HR). Upon exposure to certain range of cell death stimuli, including nutrient pathogens, plant cells in the immediately deprivation, irradiation, cytotoxic chemicals, affected area undergo a rapid cell suicide hypoxia and disease (Navarre and Wolpert response that is theoretically intended 1999). to kill the cells near the site of infection, Programmed cell death in plants thereby limiting spread of pathogens. The In plants, programmed cell death plays a HR is associated with the expression of normal physiological role in a variety of a variety of plant defense genes and the processes, including (a) deletion of cells induction of programmed cell death. The HR with temporary functions, such as the is usually preceded by rapid and transient aleurone cells in seeds and the suspensor responses, including ion fluxes, alterations

8 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 9 in protein phosphorylation patterns, pH transgenic plant tissue even with extended changes, changes in membrane potential, incubation. Similar results occurred with release of reactive oxygen species (ROS), other necrotrophic fungi including Botrytis and oxidative cross-linking of plant cell wall cinerea and Cercospora nicotianae. proteins (Richberg et al. 1998). A unifying aspect of these results with the Although plant cell suicide (HR) may be fungi tested is that all three fungal pathogens effective in limiting the spread of certain are necrotrophs; thus, these fungi require viruses, bacteria, and fungi (in particular, host plant cell death to grow, colonize those with a biotrophic lifestyle), it is and reproduce in the host milieu. In the counterproductive for limiting necrotizing case of the broad host-range pathogen S. pathogens that utilize the decaying cell sclerotiorum, it has been assumed that this corpse as a food base in the case of certain aggressive, indiscriminate pathogen with an bacteria and fungi. For example, hallmark impressive arsenal of destructive enzymes features of apoptosis have been observed and toxins simply overwhelms plants. Our in plants (during compatible interactions) data suggest that this interaction is more that are sensitive to toxin-producing sophisticated; the pathogen specifically necrotrophic fungi, including Fusarium interacts with the plant by triggering host moniliforme (fumonisin), Alternaria cell death pathways. Inhibition of this alternata (AAL toxin), and Cochliobolus pathway, presumably by anti-apoptotic gene victoriae (victorin) (Navarre and Wolpert products, prevents fungal infection even 1999, Piedras et al. 1998). Thus, plant though the fungus has its full complement programmed cell death can accompany of virulence factors. Thus, necrotrophic both susceptible and resistant reactions, pathogens may co-opt plant host cell suggesting common biochemical pathways death pathways for successful colonization during both interactions. and disease development. Redirection of Engineering resistance to pathogens plant cell death pathways by necrotrophic Proof-of-concept experiments indicate that it pathogens may be essential for disease is possible to genetically engineer plants for development to occur. pathogen resistance without interfering with Still, these results do not prove that plants normal programmed cell death responses and animals share common features of needed for plant development. For apoptosis. However, when S. sclerotiorum example, Mitsuhara et al. demonstrated that the expression in tobacco of cytoprotective The model plant Arabidopsis whose genome Bcl-2 family of proteins from humans has been sequenced

(Bcl-XL) and nematodes (CED-9) resulted in increased cellular resistance to UV irradiation and paraquat. Work in my lab has provided further evidence indicating that Bcl-2 proteins function in plants. Transgenic tobaccos were generated harboring various anti-apoptotic proteins including human Bcl-

2, chicken Bcl-XL, nematode CED-9 and baculovirus Op-IAP (Dickman et al. 2001). When the necrotrophic fungal pathogen Sclerotinia sclerotiorum, which has an extremely broad host range (more than 400 species), was inoculated onto tobacco plants harboring these transgenes, the usually susceptible plants became highly tolerant and in most cases, completely resistant. Eventually, the fungus stops growing, presumably after having depleted its nutritional source, and, importantly,

the fungus fails to colonize and infect Martin Dickman

8 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 9 was inoculated onto wild type tobacco, References DNA fragmentation was observed in the Aert R., L. Sagi. & G. Volckaert. 2004. Gene content form of characteristic “ladder”, a common and density in banana (Musa acuminata) as revealed feature of apoptotic responses. Further, by genomic sequencing of BAC clones. Theor. Appl. fungal induced DNA fragmentation was Genet. 109:129-139. detected by terminal deoxynucleotide Beers G.P. 1997. Programmed cell death during transferase-mediated dUTP end labeling plant growth and development. Cell Death and (TUNEL) of DNA 3'-OH groups which also Differentiation 4:649-661. indicated the presence of apoptotic bodies. Chern M.-S., H.A. Fitzgerald, R.C. Yadov, P.E. Canalas, Importantly, when transgenic plants were X. Dong & P.C. Ronald. 2001. Evidence for a disease- inoculated with S. sclerotiorum, not only resistance pathway in rice similar to the NPR1 were the plants resistant, but there was - mediated signaling pathway in Arabidopsis. Plant no laddering nor were there any TUNEL J. 27:101-113. positive cells. In addition, experiments Dickman M.B. & J.C. Reed. 2003. Paradigms for with tobacco mosaic virus shows that in Programmed Cell Death in Animals and Plants. Pp. N gene mediated resistance, the resulting 26-43 in Programmed Cell Death in Plants (J. Gray, HR exhibits TUNEL reacting tobacco cells ed). Blackwell Publishing, UK. and that in transgenic tobacco containing Dickman M.B., Y.K. Park, T. Oltersdorf, W. Li, T. Clemente anti-apoptotic genes, cell death (HR) is & R. French. 2001. Abrogation of disease development suppressed. Thus, we have evidence for in plants expressing animal anti-apoptotic genes. Proc. apoptotic pathways being involved in both Nat’l. Acad. Sci. 98:6957-6962. susceptible and resistant plant responses. Gale M.D., & K.M. Devos. 1998. Comparative genetics in Induction of these pathways is dependent the grasses. Proc. Nat’l. Acad. Sci. 95:1971-1974. on the genetics of the host/pathogen and Jones A.M. & J.L. Dangl. 1996. Logjam at the Styx: the life style of the pathogen. Moreover, we programmed cell death in plants. Trends in Plant have recently demonstrated that these same Science 1:114-1109. transgenic plants are tolerant to heat, cold, Li W. & M.B. Dickman. 2004. Abiotic stress induces salt and drought (Li and Dickman 2004). apoptotic-like features in tobacco that is inhibited by Importantly, these data clearly suggest expression of human Bcl-2. Biotech. Letters 26:87-95. that homologous pathways are operative in Martin G.B., A.J. Bogdanove & G. Sessa. 2003. plants and animals. Understanding the functions of plant disease We are currently in the process of resistance proteins. Annu. Rev. Plant Biol. 54:23-61. generating transgenic bananas harboring McDowell J.M. & B.J. Woffenden. 2003. Plant disease these anti-apoptotic genes. The two resistance genes: recent insights and potential major fungal diseases of bananas (black applications. Trends in Biotechnology 21:178-183. leaf streak and Fusarium wilt) both fit the Mitsuhara I., K.A. Malik, M. Miura & Y.Ohashi. 1997. conceptual framework for disease control; Animal cell-death suppressors Bcl-x(L) and Ced-9 in other words, there are necrotrophic fungi. inhibit cell death in tobacco plants. Curr. Biol. 9: Thus we are cautiously optimistic that the 775-778. transgenic bananas will exhibit tolerance/ Mittler R. & E. Lam. 1996. Sacrifice in the face of foes: resistance. We will also evaluate such lines pathogen-induced programmed cell death in plants. for tolerance to abiotic stresses (heat, cold, Trends in Microbiol 4:10-15. salt, drought). Navarre D.A. & T.J. Wolpert. 1999. Victorin induction of Conceivably, enormous opportunities exist an apoptotic/senescence-like response in oats. Plant for using animal models of programmed cell Cell 11:237-249. death to dissect cell death pathways in plants. Pennell R.I. & C. Lamb. 1997. Programmed cell death in Such information can lead to a mechanistic plants. Plant Cell 9:1157-1168. understanding of the regulation of plant cell Piedras P., K.E. Hammond-Kosack, K. Harrison & J.D.G. death, an area that is not well understood Jones. 1998. Rapid Cf9 and Avr-dependent production and is of fundamental importance for plant of active oxygen species in tobacco suspension biology. Thus understanding and eventual cultures. Mol. Plant Micro. Interact 11:1155-1166. exploitation of cell life/death pathways in Rensink W.A. & C.R. Buell. 2004. Arabidopsis to rice. plants can be used for protection of banana Applying knowledge from a weed to enhance our against pathogens and environmental understanding of a crop species. Plant Physiol. 135: stresses. 622-629.

10 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 11 Rice Chromosome 10 Sequencing Consortium. 2003. In Solomon M., B. Belenshi, M. Delledonne, E. Menachem depth view of structure. Activity and evolution of rice & A. Levine. 1999. The involvement of cysteine chromosome 10. Science 300:1566-1569. proteases and protease inhibitor genes in the Richberg M.H., D.H. Aviv & J.L. Dangl. 1998. Dead cells regulation of programmed cell death in plants. The do tell tales. Curr. Opin. Plant Biol. 1:480-488. Plant Cell 11:431-444.

Ryerson D.E. & M.C. Heath. 1996. Cleavage of nuclear Zhao B.Y., E. Ardales, E. Bresset, L.E. Claflin, J.E. Leach Martin B. Dickman works at DNA into oligonucleosomal fragments during cell death & S.H. Hulbert. 2004. The Rxo1/Rba1 locus of maize the University of Nebraska, induced by fungal infection or by abiotic treatments. controls resistance reactions to pathogenic and non- Department of Plant Pathology, Plant Cell 8:393-402. host bacteria. Theor. Appl. Genet. 109:71-79. Lincoln, Nebraska 68583 USA

Diseases and pests: A review of their importance and Pests and diseases management Randy Ploetz

iseases and pests are increasingly host range that includes the Cavendish limiting factors in smallholder and subgroup (AAA) and plantains (AAB). In D export production, and can cause some areas, eumusae leaf spot, caused catastrophic losses (Jones 2000a). Diseases by Mycosphaerella eumusae, Sigatoka, are the reason breeding programs were caused by Mycosphaerella musicola, and established in Trinidad, Jamaica, Honduras speckle, caused by Mycosphaerella musae, and Nigeria, and have been cited as a are equally or more important. Fusarium primary reason for the creation of INIBAP wilt, caused by Fusarium oxysporum f. sp. (Buddenhagen 1993). It is most appropriate cubense (Foc), is a lethal and widespread that a session of this meeting is devoted to problem on this crop (Ploetz and Pegg these production constraints. 2000). It devastated the export trade that Musa diseases and pests are significant depended on ‘Gros Michel’ AAA until ca. problems worldwide. Diseases affect all 1960. A recently recognized variant, tropical portions of the plants, are caused by fungi, race 4 (TR4), affects Cavendish cultivars and bacteria and viruses, and have been the threatens export and smallholder production subjects of entire books (Jones 2000a, of it and many other cultivars outside Stover 1972, Wardlaw 1961). Pests, its endemic, Southeast Asian range. Of although of an overall lower importance, are serious but lesser concern are: the leaf spot nonetheless serious production factors in diseases cladosporium speckle, caused by their own right (Gold et al. 2001, Gold et al. Cladosporium musae, and freckle, caused 2002, Gowen and Quénéhervé 1990). This by Guignardia musae; the post-harvest short review lists the most important of these problems anthracnose and crown rot, caused problems and concludes with a discussion of primarily by Glomerella musae; and root rots some current issues. caused by Cylindrocladium/Calonectria spp. The major diseases (Jones 2000b, Jones 2000c, Muirhead and Fungal diseases Jones 2000, Ploetz et al. 2003a). Diseases that are caused by fungi are most Bacterial diseases common and destructive (Jones 2000). Bacteria cause several types of diseases, the Leaf spot diseases caused by species of most significant of which are vascular wilts Mycosphaerella result in moderate to severe (Thwaites et al. 2000). With the exception of damage wherever significant rainfall occurs the Philippines, Moko, caused by race 2 of (Jacome et al. 2003). Black leaf streak Ralstonia solanacearum, is restricted to the disease, better known as black Sigatoka Western Hemisphere. It has eliminated the and caused by Mycosphaerella fijiensis, highly susceptible ‘Bluggoe’ (ABB) in many is most important. It occurs throughout production areas in the west. In contrast, the humid, lowland tropics and has a wide blood disease, caused by a Ralstonia sp.

10 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 11 (possibly solanacearum), is found in the The major pests Eastern Hemisphere in only some islands Nematodes are the most important pests in the Indonesian archipelago. Moko and of banana and, depending on environment blood disease produce similar symptoms and geographic location, four species on banana and have modes of transmission can cause significant damage (Gowen that include transmission by flying insects. and Quénéhervé 1990) (Figure 1). The Recently, the pathogen that causes bacterial burrowing nematode, Radopholus similis, wilt of enset, Xanthomonas campestris is the most widespread (Sarah et al. 1996). pv. musarum, has been implicated in a Pratylenchus coffeae and Pratylenchus devastating epidemic on banana in Uganda goodeyi cause equally serious damage (Thwaites et al. 2000, Tushemerierwe but are, respectively, less prevalent and et al. 2003, S. Eden-Green personal relatively uncommon on banana worldwide communication 2004). A fruit rot, Bugtok, (Bridges et al. 1997). All of the above impact which is caused by R. solanacearum, is production in the tropics, whereas the spiral restricted to the Philippines. Less important, nematode, Helicotylenchus multicinctus, but more widely spread, are rots of the causes greater damage in the subtropics rhizome and pseudostem that are caused by (McSorley and Parrado 1986). The weevil Erwinia spp. (Thwaites et al. 2000). borer, Cosmopolites sordidus, is the most Viral diseases prevalent and important insect on banana There are four significant diseases of (Gold et al. 2001). banana that are caused by viruses (Jones 2000, Ploetz et al. 2003a). Bunchy top is the most damaging and total losses can occur if early diagnosis and strict sanitation is not practiced. It is most likely caused by Banana bunchy top virus (BBTV) (cause and effect have not been demonstrated in artificially inoculated plants), and with the exception of three islands in the Hawaiian chain is only found in the Eastern Hemisphere.

Bract mosaic, caused by Banana bract Gisella ORjeda, INIBAP mosaic virus (BBMV), has a more restricted Figure 1. Damage caused by nematodes distribution in the east, and is less destructive than bunchy top. In contrast, banana streak, caused by Management Banana streak virus (BSV), and banana Options for the sustainable management of mosaic, caused by Cucumber mosaic virus these problems are usually limited. Cultural (CMV), are present in most areas where measures can be very successful against banana is grown. They usually cause minor some diseases, and the sanitation and damage, but severe strains of each exist. roguing procedures that are used against Before BSV and streak were described bunchy top and Moko disease are prominent (Lockhart 1986), streak symptoms were examples (Thomas and Iska-Caruana 2000, often confused with those of mosaic (Stover Thwaites et al. 2000). However, they are 1972, Wardla 1961). At least four strains marginally effective in other situations, of BSV that are linked to the B genome most notably deleafing for the management can be activated (become episomal) in of black leaf streak in high rainfall areas A X B germplasm via meiosis and tissue (although deleafing played a major role in the culture-induced stress (Geering et al. 2001, recent eradication of the disease in the Tully Geering personal communication 2004). area in Australia, it coincided with unusually They threaten progress in banana breeding dry weather). programmes and the safe movement of Chemical control is effective against leaf hybrid germplasm. spots, but due to its high cost it is not an

12 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 13 option for smallholders. In contrast, export New threats production of the Cavendish cultivars would Bacterial wilt epidemic in Uganda not be possible without the liberal use of Until recently bacterial wilt (BXW), caused fungicides. To a lesser extent, banana by X. campestris pv. musacearum, was pests can also be managed chemically. The viewed as a problem on enset, Ensete environmental impacts and human health ventricossum, but not banana (Thwaites issues that are associated with pesticide et al. 2000). Banana was known to be usage in banana production have received susceptible, but because it is an unimportant crop in Ethiopia, BXW was not viewed as an considerable attention (Ploetz 2000, Ploetz important banana disease. et al. 2003b). The rapidity with which BXW has moved Genetic resistance is environmentally is alarming. First recognized on a single benign and very effective against some farm in the Mukono District in October diseases and pests. Resistance to the 2000, the disease was reported in 15 sub- Mycosphaerella leaf spots, Fusarium wilt counties in four more districts by June 2003 and R. similis exists among the land races. (Tushemereirwe et al. 2003). By October They have been used to replace susceptible 2003, the disease was confirmed in 10 total clones and, whenever possible, as parents districts and suspected in eight more (see map at: http://www.cabi-bioscience.org/Html/ in conventional breeding programs. To a GlobalPlantClinic.htm). Currently, the disease lesser extent, resistance also exists in land has been confirmed in 18 districts in Uganda races against Moko, other nematodes and as well as the Democratic Republic of Congo C. sordidus; in general, it has not been used (G. Blomme personal communication 2004, in breeding programs. S. Eden-Green personal communication With few exceptions, poor natural 2004). Up to 70% of the plants have been resistance exists for the bacterial and lost in some fields (Figure 2). viral problems and nematodes other than Both exotic and East African highland R. similis. Thus, nonconventional approaches, bananas (EAHB) are susceptible. Since the pathogen is apparently moved via flying in particular genetic transformation, have insects and the disease occurs in a resource- received considerable attention when poor area, where eradication and/or control these problems have been considered in measures would be difficult to implement, improvement programmes. The extent to continued spread is probable. BXW clearly which transformed or genetically modified threatens vast areas of banana throughout bananas will solve these problems and East Africa. whether consumers will accept them are TR4 of Fusarium wilt presently unknown. I conclude with a closer The recognition of TR4 as distinct pathotype look at a few important problems. of Foc is recent. Isolates of VCG01213/

Figure 2. Plot infested with Xanthomonas campestris in the Democratic Republic of Congo (left) and infected fruit (right). Guy Blomme, INIBAP Guy Blomme, INIBAP

12 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 13 01216 have been recovered from samples 2) What alternative, non-banana hosts are sent to the author from Sumatra by R.H. present in these production areas, and Stover in early 1992, and by 1994 the what is their distribution and impact? VCG had been recovered from Cavendish 3) If the tissue culture plantlets were plantations in peninsular Malaysia and pathogen-free, was the pathogen moved Indonesia. The pathogenicity of several to the above sites by some other means? of the isolates was demonstrated on ‘Silk’ Research is needed to answer these (AAB), ‘Bluggoe’ (ABB) and ‘Grande naine’ questions and combat the situation in (AAA) (Ploetz unpublished). Southeast Asia, and a watchful eye and TR4 is now found in Australia (Northern set of contingency plans, if TR4 arrives, is Territory), Indonesia (Halmahera, Irian needed in the west (Ploetz 2003, Ploetz et Jaya, Java, Sulawesi and Sumatra), al. 2003b). Malaysia (Peninsular), Papua New Guinea, Unclear or developing threats and Taiwan (Ploetz et al. 2003a). It is Eumusae leaf spot pathologically distinct from subtropical race Since eumusae leaf spot has been 4 in that damage occurs in the absence of recognised less than a decade ago, important predisposing conditions (e.g. cold weather). attributes of the pathogen and disease are It is also genetically distinct and comprised not known. The geographic distribution of the of only isolates in VCG 01213/01216. That disease is poorly understood and probably TR4 devastates Cavendish in the tropics underestimated due to its resemblance has dire implications for export production in to black leaf streak (Figure 3). Work to Southeast Asia and the extensive Cavendish determine the disease’s occurrence and trades in the Western Hemisphere (Ploetz et prevalence outside the known affected areas al. 2003b). Since TR4 affects other important should continue. In addition, basic studies on groups, such as the AAB plantains, it also the disease’s epidemiology, management, threatens smallholder production in Western host range and impact are needed. Africa and Latin America Banana streak Minimising the spread of TR4 depends Work is needed on the epidemiology of on the strict observance of quarantine banana streak and its variable impact on measures against the movement of suckers production. Only partially understood is what and rhizomes. This would protect production distinguishes areas where serious problems in the west, but additional information occur from those where ‘Mysore’ AAB is would be needed to combat the problem in essentially the only cultivar that is affected or Southeast Asia, where the epidemiology of where infection reduces yields only slightly the disease is not well understood. Since (Daniells et al. 2001). Severe strains of BSV the pathogens appeared where banana had undoubtedly play a role, but recent results not been grown recently and in plots that from neighboring Uganda suggest that had been established with tissue culture heavily impacted areas might also be those plantlets, their source is a mystery. Relevant in which diverse vectors are present (Harper questions include: et al. 2004). All of the factors that influence 1) How long can the pathogens survive in the symptom expression are also not known absence of a banana host? (Lockhart and Jones 2000, Ploetz et al.

Figure 3: Leaf symptoms of black leaf streak disease (left) and eumusae leaf spot disease (right) Cirad D. Jones

14 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 15 2003a). Although temperature and different Fusarium wilt of banana is an especially developmental stages of the host have difficult target for biocontrol. The soil been associated with this variation, other environment in which the pathogen resides factors may be involved. Research should complicates protection of the infection site, and continue on the varied genetic makeup of the vascular location of the pathogen, once the pathogen and the activation of some infection has occurred, protects it from many integrated strains. potential biocontrol agents. Most importantly, Declining productivity in Uganda disease control must be highly effective and Banana has been cultivated in Uganda long lasting since banana is usually grown for over 1000 years and is the basis for as a perennial. In a recent review, the only subsistence agriculture in much of the successful example of the biological control East African highlands (Purseglove 1972). of a Fusarium wilt on a perennial crop was In recent decades, yields have declined of soils that suppressed the development of in central Uganda (Abera et al. 1999). Fusarium wilt of banana (Fravel et al. 2003). Although these reductions have been well To date, this trait has not been transferred to documented, their cause(s) remain(s) a disease conducive soil (i.e. it appears to be obscure. Declining fertility in these long-lived restricted to certain soil types). production systems (some plantings have Although papers on the biological control existed for several generations) has been of this disease have been published in suggested, as has reduced management referred journals, none offer real hope (Abera et al. 1999). A recent study indicates that this approach will be successful. Most that nitrogen and potassium fertility probably of these studies do not address disease play secondary roles in this phenomenon reduction in the field. Rather, they focus on and that the primary roles are more likely in vitro inhibition of the pathogen by microbial played by diseases and pests (Smithson et agents (Sivamani and Gnanamanickam 1988, al. 2001). Thangavelu et al. 2004), biochemical traits If Smithson et al. (2001) are correct, which of the host, pathogen, or their interactions diseases and pests are responsible and (Thangavelu et al. 2003), or disease reduction why they only recently impacted these old in pot studies in glasshouses (Saravanan et agroecosystems need to be determined. The al. 2003, Thangavelu et al., 2004). When field list of factors that may be involved is long studies have been reported the results have and includes nematodes, the banana weevil, been disappointing. To date, the best result several leaf spots and BSV. Given this long from a field study reported an 18% loss after list it is clear that a thorough investigation 11 months (Saravanan et al. 2003). After 5 of the variables would be an enormous years, this rate would result in total losses of task. That said, a focused, multidisciplinary over 70%! approach to understanding this problem, Clearly, future work in this area needs to wherein the major candidates were tested focus on disease reduction in field situations. in factorial experiments against one or two Without such a focus, biocontrol research important EAHB, could yield valuable insight on this disease will continue to be open to into this problem. It is hoped that BXW will substantial and justified criticism. not make such insight moot. References A final problem Abera A.M.K., F. Bagamba, C.S. Gold, E.B. Karamura Biocontrol studies on Fusarium wilt & A. Kiggundu. 1999. Geographic shifts in the highland cooking banana (Musa spp., group AAA-EA). Fusarium wilt is among the most difficult International Journal for Sustainable Development & diseases to manage on banana. Effective World Ecology 6:45-59. fungicides are not available, resistance is Bridge J., R. Fogain & P. Speijer. 1997. The root not always an important breeding target, lesion nematodes of banana:Pratylenchus coffeae and infested soils remain so for decades (Zimmermann, 1898) Filip. & Schu. Stek., 1941, Pratylenchus goodeyi Sher & Allen, 1953. Musa Pest (Buddenhagen 1990, Stover 1962). Were Fact Sheet No. 2. INIBAP, Montpellier, France. they available, effective biological control Buddenhagen I.W. 1990. Banana breeding and Fusarium measures for this disease would be most wilt. Pp. 107-113 in Fusarium Wilt of Banana (R.C. useful. Ploetz, ed.). APS Press, St. Paul.

14 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 15 Buddenhagen I.W. 1993. Whence and whither banana Ploetz R.C. 2000. Management of the most important research and development? Pp. 12–26 in Biotechnology disease of banana, black Sigatoka. Pesticide Outlook Applications for Banana and Plantain Improvement. 11:19-23. INIBAP. Montpellier, France. Ploetz R.C. & K.G. Pegg. 2000. Fusarium wilt. Pp. 143-159 Daniells J.W., A.D.W. Geering, N.J. Byrde & J.E. Thomas. in Diseases of Banana, Abacá and Enset (D.R. Jones, 2001. The effect of Banana streak virus on the growth ed.). CABI Publishing. Wallingford, UK. and yield of dessert bananas in tropical Australia. Annals Ploetz R.C., J.E. Thomas & W. Slaubaugh. 2003a. Diseases of Applied Biology 139: 51-60. of banana and plantain. Pp. 73-134 in Diseases of Fravel D., C. Olivain & C. Alabouvette. 2003. Fusarium Tropical Fruit Crops (R.C. Ploetz, ed.). CABI Publishing . oxysporum and its biocontrol. New Phytologist 157: Wallingford, Oxon, UK. 493-502. Ploetz R.C., L.W. Timmer & S.M. Garnsey. 2003b. Geering A.D.W., N.E. Olszewski, G.Dahal, J.E. Thomas & Management of tropical fruit diseases: Current overview B.E.L. Lockhart. 2001. Analysis of the distribution and and future outlook. Pp. 465-481 in Diseases of Tropical structure of integrated Banana streak virus DNA in a Fruit Crops (R.C. Ploetz, ed.). CABI Publishing. range of Musa cultivars. Molecular Plant Pathology 2: Wallingford, Oxon, UK. 207-213. Purseglove J.W. 1972. Tropical Crops. Monocotyledons 2. Gold C.S., J.E. Peña & E.B. Karamura. 2001. Biology Longman Press, London. 349 pp. and intergrated pest management for the banana weevil Cosmopolites sordidus (Germar) (Coleoptera: Sarah J.L., J. Pinochet & J. Stanton. 1996. The burrowing Curculionidae). Integrated Pest Management Reviews nematode of bananas, Radopholus similis Cobb, 1913. 6:79-155. Musa Pest Fact Sheet No. 1. INIBAP, Montpellier, Gold C.S., B. Pinese & J.E. Peña. 2002. Pests of banana. France. Pp. 13-56 in Tropical Fruit Pests and Pollinators: Biology, Saravanan T., M. Muthusamy & T Marimuthu. 2003. Economic Importance, Natural Enemies and Control Development of integrated approach to manage the (J.E. Peña, J.L. Sharp & M. Wysocki, eds). CABI fusarial wilt of banana. Crop Protection 22:1117-1123. Publishing. Wallingford, Oxon, UK. Smithson P.C., B.D. McIntyre, C.S.Gold, H. Ssali & I.N Gowen S.R. & P. Quénéhervé. 1990. Nematode parasites Kashaija. 2001. Nitrogen and potassium fertilizer of banana, plantains and abacá in Plant Parasitic vs. nematode and weevil effects on yield and foliar Nematodes in Subtropical and Tropical Agriculture (M. nutrient status of banana in Uganda. Nutrient Cycling in Luc, R.A. Sikora & J. Bridge, eds). CABI Publishing. Agroecosystems 59:39-250. Wallingford, Oxon, UK. Sivamani E. & S.S. Gnanamanickam. 1988. Biological Harper G., D. Hart, S. Moult & R. Hull. 2004. Banana streak control of Fusarium oxysporum f.sp. cubense in banana virus is very diverse in Uganda. Virus Research 100: by inoculation with Pseudomonas fluorescens. Plant and 51-56. Soil 107:3-9. Jacome L., P. Lepoivre, D. Marin, R. Ortiz, R. Romero & J.V. Stover R.H. 1962. Fusarial wilt () of Escalant (eds.). 2003. Mycosphaerella leaf spot diseases bananas and other Musa species. CMI, Kew, Surrey, of bananas: present status and outlook. Proceedings of UK. 117pp. the 2nd international workshop on Mycosphaerella leaf Stover R.H. 1972. Banana, Plantain and Abaca diseases. spot diseases held in San José, Costa Rica, 20-23 May Commonwealth Mycological Institute, Kew, Surrey, UK. 2002. INIBAP, Montpellier, France. 318pp. 316pp. Jones D.R. (ed.) 2000a. Diseases of Banana, Abacá and Thangavelu R., A. Palaniswami & R. Velazhahan. Enset. CABI Publishing. Wallingford, Oxon, UK. 544pp. 2004. Mass production of Trichoderma harzianum Jones D.R. 2000b. Cladosporium speckle. Pp. 108-111 in for managing fusarium wilt of banana. Agricultural Diseases of Banana, Abacá and Enset. (D.R.Jones, ed.). Ecosystems and Environment 103:259-263. CABI Publishing. Wallingford, Oxon, UK. Thangavelu R., A. Palaniswami, S. Doraiswamy & Jones D.R. 2000c. Freckle. Pp. 120-125 in Diseases of R. Velazhahan. 2003. The effect of Pseudomonas Banana, Abacá and Enset (D.R Jones, ed.). CABI fluorescens and Fusarium oxysporum f.sp. cubense on Publishing. Wallingford, Oxon, UK. induction of defense enzymes and phenolics in banana. Lockhart B.E.L. 1986. Purification and serology of a Biologia Plantarum 46:107-112. bacilliform virus associated with banana streak disease. Thomas J.E. & M.L. Iskra-Caruana. 2000. Bunchy top. Pp. Phytopathology 76:995-999. 241-253. in Diseases of Banana, Abacá and Enset (D.R. Lockhart B.E.L. & D.R. Jones. 2000. Banana streak. Pp. Jones, ed.). CABI Publishing. Wallingford, Oxon, UK. 262-274 in Diseases of Banana, Abacá and Enset. (D.R. Thwaites R., S.J. Eden-Green & R. Black. 2000. Diseases Jones, ed.). CABI Publishing. Wallingford, Oxon, UK. caused by bacteria. Pp. 213-239 in Diseases of Banana, McSorley R. & J.L. Parrado. 1986. Helicotylenchus Abacá and Enset (D.R. Jones, ed.). CABI Publishing. multicinctus on bananas: an international problem. Wallingford, Oxon, UK. Nematropica 16:73-91. Randy Ploetz works at the Tushemereirwe W., A. Kangire, J. Smith, F. Ssekiwoko, M. University of Florida, Tropical Muirhead I.F. & D.R. Jones. 2000. Anthracnose. Pp. 199- Nakyanzi, D. Katuma, C. Musitwa & R. Karyaija. 2003. 203 in Diseases of Banana, Abacá and Enset (D.R. An outbreak of bacterial wilt in Uganda. InfoMusa 12(2): Research and Education Jones, ed.). CABI Publishing. Wallingford, UK. 6-8. Center, 18905 SW 280th Street, Ploetz R.C. 2003. “Yes. We won’t have bananas.” What Wardlaw C.W. 1961. Banana Diseases including Plantains Homestead, FL 33031-3314 realistic threats do diseases pose to banana production? and Abaca. Longmans, Green and Co Ltd., London, UK. USA Pesticide Outlook 14:62-64. 648pp.

16 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 17 Population genetic structure and dispersal of Fungal diseases Mycosphaerella fijiensis Jean Carlier

o ensure the sustainability of haploid and heterothallic ascomycete production systems, the strategies fungus that spreads through three modes: T elaborated to manage diseases the movement of infected plant material should take into account the evolutionary (infected suckers and diseased leaves used and epidemiological factors that affect the to wrap food or other goods), the dispersal pathogens. But since such strategies will of ascospores (produced during sexual be applied on spatial and temporal scales reproduction) and the dispersal of conidia not amenable to experiments, simulation (produced during asexual reproduction) models have to be developed in order to (Gauhl et al. 2000). Whereas conidia are evaluate their efficiency and sustainability. mainly dispersed over short distances on the To be realistic, these models need to be fed plant and to nearby plants, viable ascospores parameters measured in the field, hence the might be carried a few hundred kilometers by importance of conducting studies on the wind (Parnell et al. 1998). Recent population epidemiology and populations of pathogens. and epidemiological studies of M. fijiensis Among the epidemiological and evolutio- mainly provide information on the level and nary factors that need to be evaluated, distribution of variability of the fungus and on dispersal processes and their impact on gene its dispersal. flow are fundamental to the development of epidemics and pathogen evolution. Rapid Population structure and aerial dispersal of pathogens at the global dispersal processes and continental scales can have extreme The population structure of M. fijiensis was consequences on plant diseases (Brown analysed at the global and plant scales by and Hovmøller 2002). These authors made using molecular markers (Carlier et al. 1996, a distinction between two forms of dispersal Hayden et al. 2003a, Rivas et al. 2004). from an inoculum source. The first is a rare, The results indicate that a high level of unpredictable single–step invasion involving genetic diversity has been maintained at the the transport of spores over very long plantation and plant scales. The loci were at distances and even between continents. gametic equilibrium in most of the samples This stochastic form of dispersal can also analysed, suggesting random-mating popu- be the result of transporting infected plant lations of M. fijiensis, even at the scale of the material and tends to occur mainly at a plant. Founder effects were detected at the global scale. The second form consists in the global and continental scales. The level of gradual expansion of the range of pathogen genetic differentiation between populations

populations within a continent through was highest at the global scale (Fst = 0.52 normal pathogen dispersal processes. between some continents) and almost nil

However, single-step invasions may also at the local scale (Fst = 0 between nearby be involved in the dispersal of a disease at a plantations) (Figure 1). continental scale. The population structures observed at Mycosphaerella fijiensis, which causes the global and continental scales reflect the black leaf streak disease in bananas, is an dispersal history of M. fijiensis. Southeast example of a recent fungal epidemic that Asia had the highest level of genetic has spread through the tropical world. Like diversity, supporting the hypothesis that the Mycosphaerella musicola, which causes pathogen originated in the region. In the Latin Sigatoka disease, this leaf spot disease America and Caribbean region, the highest originates in Southeast Asia (Mourichon levels of genetic diversity were observed and Fullerton 1990, Pasberg-Gauhl et al. in populations from Honduras and Costa 2000). It is still spreading and replacing Rica, corroborating the hypothesis that the M. musicola as the dominant leaf spot pathogen entered the continent in this area pathogen. Mycosphaerella fijiensis is an (Pasberg-Gauhl et al. 2000). In Africa, the

16 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 17 Level Gradual extension Single-step invasion level of genetic differentiation. Finally, the Frequent dispersal events Rare dispersal events existence of random-mating populations of M. fijiensis at plant and plantation scales are Ascospores in agreement with investigations showing the important role played by wind in the dispersal of ascospores at these scales (Rutter el al. 1998). The data could not be Conidia Infected plant material used to evaluate the relative importance of dispersal through ascospores and conidia at the plant and plantation scales since the Scale: Plant Plantation Locality Country Continent Globe cloned isolates came from ascospores only. Fst : 0.0 0.0 0.13 0.30 0.52 Estimating the dispersal distance of ascospores Figure 1 . Hypothetical relative importance levels of genetic diversity in most countries of the three dispersal modes of the fungus were similar, making it difficult to locate the Two complementary approaches were used Mycosphaerella fijiensis as a function of place(s) where the pathogen first entered to estimate gene flow and the dispersal geographical scales and genetic differentiation the continent (Pasberg-Gauhl et al. 2000). It of ascospores at the scale of a plantation between populations (estimated by Fst). is possible that the samples from Africa did and a production area (over a few hundred not include ones from or near the original kilometers). population(s). The lowest levels of genetic An indirect population genetic approach diversity were detected in Côte d’Ivoire and based on the isolation by distance model the Comoros, countries respectively located (Wright 1951) was used at the scale of a at the western and eastern extremities of the production area. In this model, dispersal distribution of the disease in Africa. occurs preferentially between nearby The results reflect the relative importance subpopulations, leading to a correlation between geographic and genetic distances. of dispersal through infected plant materials The study was conducted in Costa Rica and and ascospores depending on the Cameroon in 300-km-long production areas geographical scale (Figure 1). At the global (Rivas 2003, Coste unpublished results). In scale, the introduction of the disease on the total, more than 300 cloned monoascospore different continents is probably from infected isolates from 10 to 15 banana plantations plant material. The spread of the disease distributed along a transect were analysed within a continent probably results from the by using PCR-RFLP (Zapater et a.l 2004) limited dispersal of ascospores (Figure 2) and microsatellites (Neu et al. 1999, Zapater over a few hundred kilometers or from the unpublished results) markers. The data were movement of infected plant material. The analysed by using the method developed dispersal of M. fijiensis over long distances by Rousset (1997). A strong isolation by appears to be stochastic, which has led distance was detected in both countries, to founder effects, a limited gene flow suggesting that the mean dispersal of between established populations and, as ascospores is very much inferior to 300 km. result, a high level of genetic differentiation A direct approach based on the analysis between them. As the distance decreases, of the disease gradient (McCartney and Fitt dispersal through ascospores becomes 1998) was also used. The dispersal from an more important, which results in a lower inoculum source was analysed in an isolated plantation during a period corresponding to Figure 2. In vitro germinated and non one sexual cycle (around 4 weeks) (Abadie germinated ascospores of Mycosphaerella unpublished results). Significant spatial fijiensis. autocorrelations were detected, suggesting the existence of a disease gradient. The distribution of the disease fitted a negative exponential curve. The estimated dispersal distance of ascospores was around 30 meters, a distance very much inferior to 300 km. The results obtained using population genetic and epidemiological

Jean Carlier, Jean Cirad Carlier, approaches appear coherent.

18 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 19 Perspectives resistance in space and time. The results Similar population structures have also been of such modelling exercises can be used obtained for M. musicola (Hayden et al. 2003b, to evaluate the need to conduct other experiments on the dispersal of M. fijiensis Carlier et al 2003). The newly discovered ascospores. pathogen Mycosphaerella eumusae, which Parameters related to the selection causes eumusae leaf spot disease (Crous pressure exerted on pathogen populations and Mourichon 2002), has been observed by fungicides and host resistance should mainly in Southeast Asia (Carlier et al. also be integrated in the models developed 2000), which is not only the centre of origin to test the sustainability of disease of all three pathogen but also of the host management strategies, but the experiments genus Musa (Stover and Simmonds 1987). set up to estimate these parameters should Studying the distribution and population try to limit gene flow. For example, in a structure of the three Mycosphaerella study conducted at a local scale to evaluate pathogens in Southeast Asia would help the selection pressure exerted by host localize zones of co-evolution. Such zones resistance, gene flow was so high that it are potential sources of resistance and probably counteracted the effect of selection the host-pathogen interactions of the three (Abadie et al. 2003). pathogens could be compared. Studying the pathogen populations in their natural References systems should provide better knowledge on Abadie C., A. El Hadrami, E. Fouré & J. Carlier. their epidemiology and their evolution. 2003. Efficiency and durability of partial resistance components of bananas against black leaf streak With regards to M. fijiensis, the effect of disease. Pp. 161-168 in Mycosphaerella leaf spot genetic recombination, genetic drift and gene diseases of bananas: Present status and outlook. (L. flow on the pathogen population structure Jacome, P. Lepoivre, R. Marin, R. Ortiz, R. A. Romero and J. V. Escalant, eds). INIBAP, Montpellier. according to its reproductive strategy, Brown J.K.M. & M.S. Hovmøller. 2002. Aerial dispersal of population size and dispersal process is only pathogens on the global and continental scales and its beginning to be understood. However, the impact on plant disease. Science 297:537-541. relative importance of sexual and asexual Carlier J., M.H. Lebrun, M.F. Zapater, C. Dubois & X. reproduction over short distances has yet Mourichon. 1996. Genetic structure of the global population of banana black leaf streak fungus, to be estimated. This proportion can be Mycosphaerella fijiensis. Molecular Ecology 5:499- determined by using molecular markers 510. and samples of conidia obtained by cloning Carlier J., M.F. Zapater, F. Lapeyre, D.R. Jones & X Mourichon. 2000. Septoria leaf spot of banana: A (Chen and McDonald 1996). newly discovered disease caused by Mycosphaerella Although the relative importance on eumusae (anamorph Septoria eumusae). a continental scale of dispersal through Phytopathology 90(8):884-890. ascospores and infected plant material is Chen R.S. & B. A. McDonald.1996. Sexual reproduction plays a major role in the genetic structure of population not known, improving quarantine measures of the fungus Mycosphaerella graminicola. Genetics might limit the risk of introducing the disease 142:1119-1127. in new areas and exchanges between Carlier J., H. Hayden & G. Rivas-Platero. 2003. Genetic existing populations in different countries. differentiation in the Mycosphaerella leaf spot pathogens of bananas. Pp.123-129 in Mycosphaerella Since the dispersal distance of ascospores leaf spot diseases of bananas: Present status and appears to be restricted to only a fraction outlook. (L. Jacome, P. Lepoivre, R. Marin, R. Ortiz, of the length of a production area that is R. A. Romero and J. V. Escalant, eds.). INIBAP, a few hundred kilometers long, disease Montpellier. Crous P.W. & X. Mourichon. 2002. Mycosphaerella management should also try to limit the eumusae and its anamorph Pseudocercospora natural dispersal of the pathogen at the eumusae spp. Nov.: causal agent of eumusae leaf spot scale of a production area in order to limit disease. Sydovia 54:35-43. gene flow between pathogen populations. Gauhl F., C. Pasberg-Gauhl, & D.R. Jones. 2000. Black leaf streak. Disease cycle and epidemiology. Pp. 56-62 This epidemiological characteristic in Disease of bananas, Abaca and Enset (D.R. Jones, should be exploited to devise efficient ed.). CABI, Wallingford. and sustainable disease management Hayden H.L., J. Carlier & E.A.B. Aitken. 2003a. The strategies at the scale of producing areas. genetic structure of Mycosphaerella fijiensis from Australia, Papua New Guinea and the Pacific Islands. The estimated dispersal parameters could Plant Pathology 52:703-712. also be used in regional models to test the Hayden H.L., J. Carlier & E.A.B. Aitken. 2003b. Population effect of varying host distribution and host differentiation in the spot pathogen

18 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 19 Mycosphaerella musicola, examined at a global scale. Mycosphaerella fijiensis, champignon responsable de Plant Pathology 52:713-719. la maladie des raies noires du bananier. Thesis, Ecole Mourichon X. & R.A. Fullerton. 1990. Geographical national supérieure agronomique de Montpellier. distribution of the two species Mycosphaerella Rivas G.G., M.F. Zapater, C. Abadie & J. Carlier. musicola Leach (Cercospora musae) and M. fijiensis 2004. Founder effect and stochastic dispersal at the Morelet (C. fijiensis), respectively agents of Sigatoka continental scale of the fungal pathogen of bananas disease and black leaf streak disease in Bananas and Mycosphaerella fijiensis. Molecular Ecology 13:471- Plantains. Fruits 45:213-218. 482. Neu C., D. Kaemmer, G. Kahl, D. Fischer & K. Weising. Rousset F. 1997. Genetic differentiation and estimation of 1999. Polymorphic microsatellite markers for the gene flow from F-statistic under isolation by distance. banana pathogen Mycosphaerella fijiensis. Molecular Genetics 145:1219-1228. Ecology 8:523-525. Rutter J., P.J.A. Burt & F. Ramirez. 1998. Movement of Parnell M., P.J.A. Burt & K. Wilson. 1998. The influence of Mycosphaerella fijiensis spores and Sigatoka disease exposure to ultraviolet radiation in simulated sunlight on development on plantain close to an inoculum source. ascospores causing black Sigatoka disease of banana Aerobiologia, 14:201-208. and plantain. International Journal of Biometeorology Stover R.H. & N.W. Simmonds. 1987. Bananas. Willey & Jean Carlier works at the UMR 42:22-27. Sons, New York. 385 Biologie et Génétique des Pasberg-Gauhl C., F. Gauhl & D.R. Jones. 2000. Black Wright S. 1951. The genetical structure of populations. Interactions Plante-Parasite, leaf streak. Distribution and economic importance. Pp. Annals of Eugenics 15:323-354. 37-44 in Disease of Bananas, Abaca and Enset (D.R. CIRAD, TA 41/K, Baillarguet Zapater M.-F., A. Rakotonantoandro, F. Cohen & J. Jones, ed.). CABI, Wallingford. Carlier. 2004. PCR-RFLP markers for the fungal international campus, F-34398 Rivas G.G. 2003. Effets de fondation et différenciation banana pathogen Mycosphaerella fijiensis. Molecular Montpellier Cedex 5, France génétique aux échelles continentale et locale chez Ecology Notes 4:80-82.

Soil fertility Soil quality problems in East African banana systems and their relation with other yield loss factors P.J.A. van Asten, C.S. Gold, S.H. Okech, S.V. Gaidashova, W.K. Tushemereirwe and D. De Waele

n the banana growing areas of the East crop cycle is highly variable and depends African highlands (Uganda, Rwanda, on cultivar, plant nutrition and climate, (iv) I Burundi, East Democratic Republic of bunch weights show high spatial variability Congo, Northwest Tanzania, and West at regional, village and farm level, and Kenya), bananas occupy up to 30% of the (v) bananas are often cultivated in mixed cultivated land. The area is characterized by cropping systems and at mixed densities, medium to high altitudes (900 - 2000 masl) complicating yield calculations on a per and the presence of moderate to steep hectare basis. Yield data presented by FAO slopes that are prone to erosion. However, and government bodies are mostly based erosion under the permanent banana on rough estimates. Their data show that canopy is much smaller (<30%) than in yields were mostly stable, while production annual cropped fields (Lufafa et al. 2003). and cultivated area increased steadily over In the last decades, concerns that banana the last 40 years (FAO 2004). Nonetheless, yields in this region are declining have been reports on banana yield decline go back voiced so often, that it is now considered as an established fact (Anonymous 2001, to the 1940s and 1950s (McMaster 1962, Baijukya and Steenhuijsen Piters 1998, Masefield 1949) and have persisted ever Rishirumuhirwa 1997, Woomer et al. 1998). since. However, most reports on yield decline are The lack of reliable banana production based on farmers perceptions (Gold et al. figures makes it difficult to quantify yield 1999), since there is a general lack a good decline and the importance of different yield quality yield documentation. Unfortunately, loss factors. Whether there is a yield decline it is very difficult to obtain reliable yield data or not, whether production figures are from farmer fields because: (i) there is no accurate or not, it is clear that actual yields single harvest period, (ii) bunch weights of 5-30 t ha-1 yr-1 are very far from the 60-70 are season dependent, (iii) the length of the t ha-1 yr-1 attained in on-farm and on-station

20 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 21 trials in the region (Smithson et al. 2001; al. 2004). However, one should be cautious Tushemereirwe et al. 2001). to draw conclusions on nutrient deficiencies from soil chemical analysis alone, since Actual soil quality problems most studies find a poor correlation between The hypothesis that soil fertility decline soil fertility parameters and bunch yields contributed to declining banana yields in (Bananuka and Rubaihayo 1994, Rufino the region was first advanced by Masefield 2003, Smithson et al. 2001). (1949) and McMaster (1962) and has Most of the studies that used foliar analysis been repeated ever since (Baijukya and (Bosch et al. 1996, Gold et al. 1999, Okech de Steenhuijsen Piters 1998, Bekunda et al. 2004, Rufino 2003, Smithson et al. and Woomer 1996, Sseguya et al. 1999). 2001, Smithson et al. 2004, Ssali et al. 2003) However, there are very few data to test identified K deficiency as a major constraint, this hypothesis. In Uganda, Smithson et al. often followed by N and Mg. Phosphorus (2001) and Ssali and Vlek (unpublished) deficiency does not seem to be a frequent have attempted to compare quantitative problem for East African highland bananas. soil data from the 1960s and 1990s. Both Little research has been conducted on studies failed to find a change in organic micronutrients. Bosch et al. (1996) found matter content, but Ssali and Vlek observed very low Zn and Cu when compared to DRIS a decrease in soil pH, exchangeable Ca2+ norms established for other AAA cultivars. and K+. Another method to detect nutrient Most highland bananas are grown on deficiencies is by conducting fertilizer trials. ferralsols and acrisols soils, which have Several studies that applied moderate a low fertility. However, a substantial fertilizer doses of N (100 kg), P (<100 kg) proportion of the bananas in the region is and K (25-200 kg) per hectare observed grown near the homestead (Rishirumuhirwa yield increases from 10-12 to 16-25 t ha-1 yr-1 1997, Rufino 2003). These homestead plots (Okech et al. 2004, Rubaihayo et al. 1994, receive organic household residues and are Zake et al. 2000). However, fertilizers seem more often mulched than plots further away. to be less effective when nematode and Bekunda and Woomer (1996) and Wortmann weevil pressure are high (Smithson et al. and Kaizzi (1998) found that most farmers 2001, Ssali et al. 2003), or when prolonged transferred annual crop residues to banana drought stress occurs (Okech et al. 2004). fields. Farmers also tend to allocate their best Soil physical properties and topsoil depth land to the banana crop (Gold et al. 1999). directly affect the rootability and water Both land choice and soil management for holding capacity of the soil. The latter bananas explain why banana fields contain influence the ability of roots to extract water more nutrients (especially P and K) than and nutrients. Taulya (2004) observed that annual cropped fields and plots further away bunch weight increase from 8 to 16 kg when from the homestead (Bosch et al. 1996, moving from soils with a shallow (<20 cm) to Rufino 2003, Wortmann and Kaizzi 1998). a deep (>30 cm) A-horizon. Despite the fact Researchers worldwide (Bertsch 1986, that soil moisture stress can lead to more Delvaux 1995, Lahav and Turner 1983, than 60% yield loss (Okech, unpublished), Landon 1991, Lopez and Espinoza 2000, soil physical aspects have received relatively Rubaihayo et al. 1994, Twyford 1967, little attention in the region. Walmsley et al. 1971) have published guidelines for the interpretation of chemical Potential soil quality problems soil data for banana farmers. These Over the last decades, bananas have guidelines mostly address commercial desert increasingly become a cash crop in the bananas (AAA). Although the minimum soil region to satisfy the growing urban markets. requirements published vary (e.g. from 0.2 to As a consequence, more and more nutrients 1.5 meq 100g dry soil for exchangeable K), are being lost from the farm and end up most banana soils in the region (Banananuka in urban areas from which recycling back and Rubaihayo 1994, Godefroy et al. to agriculture is barely feasible (Bekunda 1991, Rufino 2003, Smithson et al. 2001, and Manzi 2004) (Figure 1). The banana Wortmann and Kaizzi 1998, Rubaihayo et al. bunches, especially the peel, are particularly 1994) have optimum soil fertility according to rich in K and exportation of this element is the average of the guidelines (Van Asten et of major concern. If nutrients exported from

20 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 21 minimum mulch quality and quantity should be to economically address soil fertility, soil microclimate and soil pest constraints. Profitable minimum mulch recommendations are especially important now that access to mulch has declined due to the shortage of uncultivated land. In order to compensate for nutrients lost, Smithson and Giller (2002) pleaded for the judicious use of mineral fertilizers to maintain soil fertility. According to them, the use of organic fertilizers and leguminous crops is important, but can not compensate for all nutrients lost from the system in most cases. Most commercial banana growers elsewhere in the world use mineral fertilizers to sustain high yield levels. However, less than 5% of banana farmers in the East African highland

Piet Asten van region use chemical fertilizers (Bekunda and Woomer 1996, Sseguya et al. 1999, Kelly et al. 2001). In general, the use of Figure 1. It is estimated that up to 100 trucks banana fields are not replenished by organic mineral fertilizer in this region is amongst full of bananas enter Kampala daily. On an or inorganic fertilizers, then this leads to the annual basis, this represents the export from the lowest in the world. Both Bekunda rural areas of over 1.5 million kg K and 0.5 mining of soil nutrient stocks and inevitably et al. (2001) and Sseguya et al. (1999) million kg N. to yield decline in the long run. This problem showed that non-availability of credit is one can be observed in many African farming of the major constraints for the adoption of systems (Smaling 1993, Hartemink 2003). chemical fertilizers. Also, farmers often lack Wortmann and Kaizzi (1998) found that knowledge on which fertilizers to use and loss of N and P at four Ugandan banana how to apply them, and smallholder farmers sites was compensated by the large amounts tend to be risk averse. Another constraint of organic materials that were transferred that hampers adoption of fertilizers might from other land use types (annual crops, be the long duration of the banana crop grassland) to the banana plots. Although N cycle, requiring the farmer to be patient and P balances might sometimes be positive before he sees a return on his investment. for banana plots, the transfer of nutrients Furthermore, Bekunda and Woomer (1996) from annual crop plots and grassland plots concluded that there is a lack of research to banana plots leads to an acceleration of on optimal fertilizer recommendations and soil exhaustion at the majority of the farm rates for banana. Bekunda and Manzi (2004) land and cannot prevent a general decline found that those farmers that did use mineral in soil nutrient stocks at the farm level. In fertilizers were putting more emphasis on addition, soils under annual crops lose N fertilization than on P and K fertilization, many nutrients through harvest and erosion although the authors agree with Wortmann (Wortmann and Kaizzi 1998), a process that and Kaizzi (1998) that in the long term, there is further accelerated when vegetation cover is a greater need for P and especially K is reduced due to soil fertility decline. Some fertilizers, than for N fertilizers. researchers suggest that an increase in The greatest problem is that the cost livestock should be part of the solution, but of maintaining soil fertility may not be Bekunda and Woomer (1996) and Sseguya compensated by an increase in crop et al. (1999) have shown that the use of production. On the other hand, the costs cattle manure is closely related to farm size to restore degraded soils may be higher and that the latter is continuously shrinking than those required to maintain the soil under increasing land pressure. Although in favorable condition for crop production both farmers and researchers agree that (Hartemink 2003). This is particularly true mulch is beneficial for banana plant growth, in the East African highlands, where high no recommendations exist on what the transport costs lead to high fertilizer costs.

22 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 23 Interaction with other yield loss positive effect of (in)organic soil amendments factors is greatly reduced if pest pressure is high. Hence, soil fertility management should best Soil born pests, such as nematodes be combined with pest management in order (Radopholus similis and Pratylenchus goodeyi) to increase the profitability of the soil fertility and the banana weevil, Cosmopolites sordidus interventions. (germar), attack the plant root and vascular If we want to improve the sustainability system. This reduces the capacity of the of banana systems, we should look beyond plant to take up water and nutrients, which the banana field and address soil fertility may aggravate drought and nutrient stress constraints at the farm level. The role of in the plant. There is also a clear interaction banana-intercropping systems, the role of between soil fertility level and the expression the permanent banana canopy for soil- and and severity of diseases; e.g. in Uganda, water conservation, and the effect of pests Murekezi (pers. comm.) and Tushmereirwe and diseases on the profitability of soil (unpublished) observed that crop damage management interventions deserve special due to Banana streak virus and black leaf attention. streak disease decreased with improved soil fertility management. In many cases, a well- Acknowledgements fertilized host plant will outgrow the attacks The authors would like to acknowledge the by pest and diseases, thereby maintaining ‘Vlaamse Vereniging voor Ontwikkelingshulp sufficient healthy biomass to sustain en Technische Bijstand’ (VVOB) for optimum growth. supporting P.J.A. van Asten’s position at Okech and Gold (1996) concluded from a IITA-ESARC, Uganda. literature review that phytophagous insects are sensitive to nutritional changes in host References Adupa R. & D.S. Ngambeki. 1994. Demand and plants. Bosch et al. (1996) suggested that consumption of bananas in Uganda. African Crop damage caused by the banana weevil might Science Conference Proceedings 1:379-383 be related to plant and soil phosphorus Anonymous. 2001. Rwanda development indicators 2001. and cation concentrations, with special Ministry of Economy and Finance 4:28-33. Bananuka J.A. & P.R. Rubaihayo. 1994. Banana emphasis on the K/Mg ratio. However, management practices and performance in Uganda. the relationship between plant nutritional Pp. 177-182 in African Crop Science Conference status and damage by weevil infestation Proceedings Vol. 1 African Crop Science Society, Uganda. has never been confirmed. Talwana (2002) Baijukya F.P. & B. de Steenhuijsen Piters. 1998. Nutrient found higher Ca concentrations in nematode balances and their consequences in the banana- infected East African highland bananas based land use systems of Bukoba district, northwest Tanzania. Agric Ecosyst Environ 71:147–158. (AAA) and hypothesized that Ca plays Bekunda M. & G. Manzi. 2004. Use of the partial nutrient a role in the plant defense mechanism. budget as an indicator of nutrient depletion in the Similarly, Bwamiki (2004) suggested that highlands of southwestern Uganda. Nutrient Cycling in Agroecosystems 67:187-195. mechanisms of nematode suppression are Bekunda M.A. & P.L. Woomer. 1996. Organic resource linked to K, Ca, Mn, and Zn uptake. Borges management in banana-based cropping systems of the Perez et al. (1983) found that imbalance in Lake Victoria Basin, Uganda. Agriculture, Ecosystems and Environment 59:171-180. P/Zn and K/Mg ratios led to Fusarium wilt in Bekunda M.A., S.T. Nkalubo, H. Sseguya, P.L. Woomer a cultivar that was supposed to be resistant. & R. Muzira. 2001. Better banana-based agriculture in Likewise, Hecht Buchholz et al. (1998) Uganda (BETBAN): identifying the limiting nutrient(s) as a basis for rehabilitating degraded banana found that Zn-deficient bananas were more fields. Pp.95-98 in Forum working document No. 2: affected by Fusarium wilt than non-deficient summaries of forum research and development plants. Hence, a range of studies on various activities at Makerere University 1993-2000. pests and diseases all seem to suggest Bertsch F. 1986. Manual para interpretar la Fertilidad de los Suelos. Oficina de publicaciones de la Universidad that the plant’s defense mechanisms are de Costa Rica. San José, Costa Rica. 81pp. closely related to the cation balance and Borgez Perez A., I. Trujillo Jacinto del Castillo, F. Gutierrez micronutrient concentrations in the plant Jerez & D. Angulo Rodriguez. 1983. Estudio sobre el mal de Panama en las Islas Canaria. II. Influencia de tissue, but the underlying processes have los desequilibros nutritivos P-Zn y K-Mg del suelo, en not yet been identified. la alteracion de los mecanismos de resistencia de la Numerous researchers (McIntyre et al. platanera (Cavendish enena) al mal de Panama. Fruits 38:755-758. 2000, Rukazambuga et al. 2002, Smithson Bosch C., A. Lorkeers, M.R. Ndile & E. Sentozi. 1996. et al. 2001) have demonstrated that the Diagnostic survey: constraints to banana productivity in

22 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 23 Bukoba and Muleba districts, Kagera region, Tanzania. hauts plateaux de l’Afrique centrale. Thèse EPFL No. Working paper no. 8. Tanzania/Netherlands Farming 1636. Lausanne. 321pp. Systems Research Project, Lake Zone. Ari Muruku, Rubaihayo P.R., O.J.B. Odongo & J.A. Bananuka. 1994. Bukoba, Tanzania. 119pp. Some highland banana production constraints in Bwamiki D.P. 2004. Role of Plant Nutrition on Growth Masaka district of Central Uganda. Pp. 188-192 in Parameters of Banana and the Suppression of African Crop Science Conference Proceedings vol. 1. Populations and Damage of Radopholus Similis. PhD African Crop Science Society, Uganda. thesis. Cornell University, United States of America. Rufino M. 2003. On-farm Analysis of Nematode Infestation Delvaux B. 1995. Soils. Pp. 230-257 in Bananas and and Soil Fertility as Constraints to the Productivity Plantains. (S. Gowen, Ed.). Chapman and Hall, of Banana-based Production Systems in Uganda. London, UK. MSc Thesis Plant Sciences, Wageningen University, FAO. 2004. Faostat agricultural data. Internet: http: Wageningen. 91pp. //apps.fao.org Rukazambuga N.D.T.M., C.S. Gold, S.R. Gowen & P. Gold C.S., E.B. Karamura, A. Kiggundu, F. Bagamba Ragama. 2002. The influence of crop management & A.M.K. Abera. 1999. Geographic shifts in highland on banana weevil, Cosmopolites sordidus (Coleoptera: cooking banana (Musa spp., group AAA-EA) production Curculionidae) populations and yield of highland in Uganda. International Journal of Sustainable cooking banana (cv. Atwalira) in Uganda. Bulletin of Agriculture and World Ecology 6:45-59. Entomological Research 92:413-421. Godefroy J., V. Rutunga & A. Sebahutu. 1991. Les Smaling E.M.A.. 1993. Soil nutrient depletion in sub- terres de bananeraies dans la région de Kibungo au Saharan Africa. Pp 53-57 in The Role of Plant Rwanda : résultantes du milieu et des systèmes de Nutrients for Sustainable Food Crop Production in culture. Fruits 46:109-124. Sub-Saharan Africa. (H. Van Reuler and W.H. Prins, Hartemink A.E. 2003 Soil fertility decline in the tropics eds). Dutch Association of Fertilizer Producers (VKP), with case studies on plantations. 360 pp. ISRIC-CABI, Leidschendam, Netherlands. Wallingford. Smithson P.C., B.D. McIntyre, C.S. Gold, H. Ssali, & I.N. Kashayij. 2001. Nitrogen and potassium fertilizers Hecht-Buchholz C., A. Borges-Perez, M. Fernandez vs. nematode and weevil effects on yield and foliar Falcon & A.A. Borges. 1998. Influence of zinc nutrition nutrient status of banana in Uganda. Nutrient Cycling on fusarium wilt of banana – an electron micropscopic in Agroecosystems 59:39-50. investigation. Acta Horticulturae 490:277-283. Smithson P.C. & K.E. Giller. 2002. Appropriate farm Kelly V.A., E. Mpyisi, A. Murekezi & D. Neven. 2001. management practices for alleviating N and P Fertilizer consumption in Rwanda: past trends, future deficiencies in low-nutrient soils of the tropics. Plant potential, and determinants. Paper presented at Policy and Soil 245:169-180. Workshop on Fertilizer Use and Marketing. 22-23 February 2001. MINAGRI & USAID. Rwanda Smithson P.C., B.D. McIntyre, C.S. Gold, H. Ssali, G. Night & S. Okech. 2004. Potassium and magnesium Lahav E. & D.W. Tuner. 1983. Banana Nutrition. Bulletin fertilizers on banana in Uganda: yields, weevil damage, 7. International Potash Institute, Woblaufen-Bern, foliar nutrient status and DRIS analysis. Nutrient Switzerland. 62pp. Cycling in Agroecosystems 69:43-49. Landon J.R. (Ed.). 1991. Booker Tropical Soil Manual; Ssali H., B.D. McIntyre, C.S. Gold, I.N. Kashaija & F. a Handbook for Soil Survey and Agricultural Land Kizito. 2003. Effects of mulch and mineral fertilizer on Evaluation in the Tropics and Subtropics. Longman, crop, weevil and soil quality parameters in highland Essex, England. 474pp. banana. Nutrient Cycling in Agroecosystems 65:141- Lopez A. & J. Espinosa. 1995. Manual de Nutrición y 150. Fertilizatión del Banano. INPOFOS. Quito-Equador. Sseguya H., A.R. Semana & M.A. Bekunda. 1999. Soil Lufafa A., M.M. Tenywa, M. Isabirye, M.J.G. Majaliwa & fertility management in the banana-based agriculture P.L. Woomer. 2003. Prediction of soil erosion in a Lake of central Uganda: farmers constraints and opinions. Victoria basin catchment using a GIS-based Universal African Crop Science Journal 7:559-567. Soil Loss Model. Agricultural Systems 76:883-894. Talwana H.L. 2002. Spatial Distribution and Effect of Masefield G.B. 1949. The Uganda Farmer. Longman, Plant-Parasitic Nematodes on Root Systems and Plant London. Nutritional Status of Bananas in Uganda. Doctoral McIntyre B.D, P.R. Speijer, S.J. Righa & F. Kizito. Thesis No. 512. Faculty of Agricultural and Applied P.J.A. van Asten, C.S. Gold 2000. Effects of mulching on biomass, nutrients and Biological Sciences of the Katholieke Universiteit and S.H. Okech work at the soil water in bananas inoculated with nematodes. Leuven. 133pp. Agronomy Journal 92:1081-1085. Taulya G. 2004. Topsoil depth-banana yield relationshiops International Institute of Tropical McMaster D.N. 1962. A Subsistence Crop Geography on a chromic luvisol in a Lake Victoria basin Agriculture, P.O. Box 7878, of Uganda. The world land use survey. Occasional microcatchment. MSc thesis. Makerere University, Kampala, Uganda, papers no. 2. Geographical Publications Limited. Bude, Uganda. 72pp. S.V. Gaidashova at the Institut Cornwall, England. 111pp. Tushemereirwe W.K., D. Karamura, H. Ssali, D. Bwamiki, Okech S.H.O. & C.S. Gold. 1996. Relationships of the I. Kashaija, C. Nankinga, F. Bagamba, A. Kangire & R. des Sciences Agronomiques banana weevil with its host plant and soil fertility; Ssebuliba. 2001. Bananas (Musa spp). in Uganda. du Rwanda, B. P. 138, Butare, literature review with emphasis on studies in eastern Pp. 281-321 in Volume II: Crops. (J.K. Mukiibi, Ed.). Rwanda, W.K. Tushemereirwe and central Africa. The African Highlands Initiative Agriculture, Fountain Publichers, Kampala, Uganda. Technical Reports Series no. 2. International Centre for Twyford I.T. 1967. Banana nutrition: a review of principles at the Kawanda Agricultural Research in Agroforestry. Uganda. 22pp. Research Institute, P.O. Box and practice. J. Sci. Food Agri. 18:177-183. Okech S.H., P.J.A. van Asten, C.S. Gold & H. Ssali. 2004. Van Asten P.J.A., C.S. Gold, J. Wendt, D. De Waele, 7065, Kampala, Uganda, Effects of potassium deficiency, drought and weevils on S.H.O Okech, H. Ssali & W.K. Tushmereirwe. 2004. and D. De Waele at the banana yield and economic performance in Mbarara, The contribution of soil quality to banana yield problems Katholieke Universiteit Leuven, Uganda. Uganda Journal of Agricultural Sciences and its relation with other banana yield loss factors in 9:511-519. Uganda. African Crop Science Journal. Proceedings of Kasteelpark Arenberg 13, B- Rishirumuhirwa T. 1997. Rôle du bananier dans le the banana IPM workshop held in Kampala, December 3001 Leuven, Belgium. fonctionnement des exploitations agricoles sur les 2003. In press.

24 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 25 Wamsley D., T. Twyford & I.S. Cornforth. 1971. An systems of Uganda. Agriculture Ecosystems and evaluation of soil analysis methods for nitrogen, Environment 71:115-129. phosphorus and Potassium, using Banana. Tropical Zake Y.K., D.P. Bwamiki & C. Nkwiine. 2000. Soil Agriculture (Trinidad) 48:141-155. management requirements for banana production Woomer P.L., M.A. Bekunda, N.K. Karanja, T. on the heavy soils around Lake Victoria in Uganda. Moorehouse & J.R. Okalebo. 1998. Agricultural Pp. 285-292 in Proceedings of the first International resource management by smallholder farmers in East Symposium on Banana and Plantain for Africa (K. Africa. Nature and Resources 34:22-33. Craenen, R. Ortiz, E.B. Karamura & D.R. Vuylsteke, Wortmann C.S. & C.K. Kaizzi. 1998. Nutrient balances eds.). Acta Horticulturae 540. International Society for and expected effects of alternative practices in farming Horticultural Science, Leuven, Belgium.

New technologies to increase root health and crop Soil fertility production Richard A. Sikora and Luis E. Pocasangre

he burrowing nematode Radopholus is unacceptable both economically to similis is a major root health problem the growers and environmentally to the T in banana and plantain. The community at large. nematode causes large root lesions that With the loss of and/or phasing out of are subsequently colonized by deleterious nematicides for economic or environmental fungi and bacteria. This syndrome leads to reasons, new approaches to nematode severe necrosis and the girdling of individual control in perennial crops are needed (Sikora roots, yield loss and often pseudostem et al. 2005). In banana production where high toppling. Control of the burrowing nematode yields are correlated with effective nematode in established plantations is usually accom- control and a healthy root system, alternative plished with systemic nematicides/insecticides. methodologies, whether biological, plant These pesticides usually only inactivate the based or chemical nature, are urgently nematode within the host tissue or in the required. soil for a limited length of time and are in most cases not nematicidal. After microbial Biological enhancement degradation of the compounds, the nematode One recently developed alternative to recovers and damage to the root continues. pesticides is biological enhancement of Due to this short-term improvement in root banana planting material with beneficial health, yield increases following treatment microorganisms to increase plant resistance in areas where the nematode is above the to infection. The fact that most of the major damage threshold level. pests and diseases of banana attack Whether or not treatment is required is the plant through the roots or corm has either open to question or determined by led to research on the use of biological past yield experience or, in some cases, enhancement technologies using mutualistic by monitoring root population densities. fungal endophytes to manage nematodes, Lack of treatment in heavily infested fields wilts and weevils (Amin 1994, Schuster et results in lower yield. However, because al. 1995, Pocasangre 2000, Pocasangre et the nematode is only inactivated by most of al. 2000, Griesbach 1999, Niere et al. 1998). these pesticides, repeated treatment within These unique antagonists are isolated a cycle is required to prevent damage over at random from the endorhiza of healthy time. The repeated use of nematicides has banana root or corm tissue following surface led to rapid microbial breakdown in some sterilization (Figure 1). The isolates are areas, and the need for an increase in then: 1) placed in pure culture 2) identified the number of treatments per cycle. In 3) mass fermented 4) inoculated onto tissue some plantations in Central America up culture plantlets 5) allowed to colonize to four applications are currently being 6) challenged with target organisms 7) and used to reduce damage. This situation then antagonistic activity measured.

24 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 25 Isolation of endophytic fungi from banana tissue is sustainable over multiple crop cycles

rhizome also is under investigation. The system is water agar presently targeted for use in 1) single-cycle high density banana production, 2) single- cycle high density plantain production, 3) inner organic bananas and 4) nursery production surface sterilization of resistant banana cultivars. outer NaOCI transfer of mycelium cutting of small Suppressive soils and biological tissue pieces general cutting of enhancement infested tissue material The term suppressiveness is traditionally used to describe soils in which disease pure culture development is suppressed even though a pathogen or pest is present in the field (Baker and Cook 1974, Huber and Schneider root 1982). It is an umbrella term encompassing biocontrol activity based on parasitism, Figure 1. Techniques used in the isolation of Isolates effective at controlling the predation, inhibition, competition, disease fungi growing inside healthy tissue of banana burrowing nematode have been recovered and other antagonist interactions with pests (Sikora & Schuster 1999). from Indonesia, Uganda, Kenya, Cuba, or disease where reduced infection occurs in Honduras and Costa Rica and, in our opinion, the presence of a susceptible host plant. will be detected in the healthy tissue of all Suppressive soils have been identified banana plants. Under normal field conditions for fungal pathogens (Huber and Schneider these endophytes are usually not effective 1982, Alabouvette et al. 1979, Weller because their densities are low and they 1988) and plant parasitic nematodes (Kerry must compete with other microorganisms et al. 1982, Pyrowolakis et al. 2002). To for food and space. Biological enhancement our knowledge this phenomenon has not gives these microorganisms a head start been observed for soil-borne insects. and competitive advantage. Biological Suppressiveness is usually directly related enhancement also reduces overall treatment to the level of the antagonistic potential in costs as well as environmental side effects the soil (Sikora 1992) which is regulated by caused by pesticides since 2500 sterile specific components of rhizosphere specific tissue culture plants can be treated in microbial communities (Vilich and Sikora pots, as opposed to treating with pesticides 1998). Suppressive soils are - the exception large quantities of soil in the field. The and not the rule - in agricultural ecosystems. approach until now has been based on a We believe however that in perennial crop “blind” screening system in which fungi are production they may be more common than randomly isolated from healthy plant tissue once thought. We believe this to be the and tested on inoculated banana plantlets for situation in all crops where plant parasitic biological control activity. nematodes are a major pest problem and A large percentage of the isolates obtained where constant use of nematicides is the from the endorhiza have demonstrated rule and not the exception. significant antagonistic activity toward the burrowing nematode (Pocasangre 2000, Suppressive soils and banana Niere et al. 1998). Activity against Fusarium In reviewing the literature on banana, there wilt was not adequate (Pocasangre 2000). is a void with regards to the detection of soil However, some isolates were shown to that suppress nematodes. The presence be pathogenic on eggs of Cosmopolites of suppressive soils may have been over- sordidus and to have negative effects on looked in crops such as banana, coffee, the growth of weevil larvae (Griesbach 1999, citrus or pineapple, due to an extensive Gold et al. 2003). use of soil pesticides. A suppressive soil Biological enhancement has been shown cannot be detected if nematode densities to be effective in reducing nematode attack are continuously lowered with pesticides. in the first cycle under controlled conditions Moreover, if a suppressive soil is identified and is being tested in the field in Africa and can it be used for pest and disease Central America. Whether or not control management purposes?

26 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 27 80000 This vacuum has been recently filled by c the detection of suppressive soils in banana Meloidogyne spp. plantations in Central America (Figure 2). 70000 Helicotylenchus spp. The burrowing nematodes present in these 60000 fields were unable to multiply and reach Radopholus similis damaging population densities even though 50000 a highly susceptible cultivar was being grown (zum Felde 2002, zum Felde et al. 40000 b 2004). Fields that suppress R. similis have also been detected in fields in Costa Rica 30000

(Pocasangre et al. 2004, Cañizares 2003). Number of nematodes / 100 g root 20000 a Biodiversity in suppressive soils 10000 Suppressive activity in any soil is regulated a by the antagonistic potential in that soil 0 (Sikora 1992). One or more microorganisms El Real Maya Creek Lourdes Farms – working singly or in combination and sim- ultaneously or sequentially – are responsible Figure 2. Total number of nematodes recovered from banana roots in sampled farms in October 2001 (zum Felde et al. 2004). (Columns with different letters are significantly different at P ≤ 0.05, using the one-way ANOVA test in for suppressive activity. Suppressiveness StatsGraphics Plus 3.1). is not driven by abiotic factors, but is a biologically based system. future research is conducted (zum Biological enhancement to control Felde 2000, zum Felde et al. 2004). The R. similis in most studies has been based question that arises is, is this phenomenon on inoculation of tissue culture plantlets important for banana production and can with fungal antagonists. Griesbach (1999) it be used effectively in pest management attempted to inoculate East African highland systems? The following applications can banana suckers with endophytes but be envisioned 1) suppressive fields could obtained only low levels of colonization. be used for nurseries to produce suckers for Recent studies by Pocasangre et al. (2004), surrounding fields, 2) biologically enhanced however, have demonstrated that R. similis plantlets could be produced from multiple densities in plantain suckers inoculated with isolates from these fields, and 3) biologically endophytic fungi were reduced by up to 86% enhanced suckers could be inoculated with over the controls. multiple isolates from these fields. In Table 1, the extremely high level of fungal biodiversity in the endorhiza of In planta suppressiveness healthy banana root and corm tissue in The concept of “in planta suppressiveness” Thailand is presented (Sikora et al. 2003). proposed here is based on the premise These results demonstrate that we have only touched the peak of an enormous volcano of Table 1. Fungal endophyte biodiversity in banana root and rhizome tissue of ‘Pisang biotic potential that can be used for plant awak’ (ABB) from Thailand (Sikora et al. 2003). Fungal species Roots Central cylinder Rhizome cortex Overall health improvement. (%)* (%) (%) (%) The organisms involved in forming a Acremonium spp. 15.4 6.7 7.5 9.9 suppressive soil in other crops have been A. stromaticum 11.5 6.7 5.0 7.7 identified and, in a limited number of cases, Aspergillus spp. 5.4 5.3 2.5 4.4 Colletotrichum musae 2.3 9.3 11.2 7.6 commercially produced for field use. Grower Cylindrocarpon spp. 3.1 1.3 5.0 3.1 acceptance is often limited, because of the Fusarium Sect. Arthrosporiella 5.4 10.7 11.3 9.1 large variability in effectiveness and the Fusarium Sect. Liseola 2.3 4.0 3.7 3.3 costs of application. Controlling the pest Fusarium oxysporum 7.7 6.7 15.0 9.8 requires treating 2500 tonnes of soil per Fusarium solani 0.8 6.7 6.3 4.6 Fusarium spp. 3.1 4.0 1.2 2.8 hectare in the top 25 cm inhabited by the Gongronella spp. 7.7 6.7 3.8 6.1 targeted pest or pathogen. Penicillium spp. 21.5 10.7 5.0 12.4 The detection of suppressive soils in Zygomycetes 4.6 4.0 1.2 3.3 banana plantations in Central America Other species** 9.2 17.2 21.3 15.9 and the isolation of large numbers of * Percentage of total number of fungal isolates from a total of 285 isolates identified. The number of fungi isolated from roots, central cylinder and rhizome cortex were respectively 130, 75 and 80. mutualistic fungal endophytes from plants ** Mainly fungi belonging to the genera: Cladosporium, Cylindrocladium, Dreschslera, Lasiopdiplodia, Plectosporium, growing in these fields should affect how Thielaviopsis and Trichoderma.

26 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 27 that plants actively select health-promoting Mode of action microorganisms from the rhizosphere. Plants Up until recently, little has been known lose up to 33% of their assimilates to the soil. about the mechanisms of action involved The exudates move through the endorhiza in the endophyte control of nematodes. This onto the rhizoplane before leakage moves knowledge is extremely important since it them into the rhizosphere. The production determines how this management system of these nutrients utilizes significant amounts is categorized: biological enhancement or of plant energy, which are ultimately lost by biological pesticides. This of course has the plant. We believe plants expend this importance in registration and therefore for energy to maintain a health support system overall costs of development. made up of “endorhiza and rhizosphere There are many possible mechanisms specific microbial communities”. These of action: 1) parasitism or pathogenicity organisms live in a mutualistic and/or to the nematodes or eggs; 2) suppression symbiotic association with the plant. The of nematode development or fertility; well-known arbuscular mycorrhizal fungi are 3) inhibition of mobility, 4) interference with part of this microbial community and have attraction or recognition; 5) inhibition of been shown to have both plant growth and penetration; 6) repellent activity; 7) induced health promoting activity (Jaime Vega and resistance and 8) plant growth promotion Rodriguez-Romero 2004). induced tolerance. The detection of fields suppressive to Studies in Bonn, Germany and at a migratory endoparasitic nematode also INIBAP-CATIE, Turrialba, Costa Rica, have suggests that the basis of suppressiveness shown repeatedly that many of the fungal may be plant-bonded. Biological control endophytes studied significantly reduced activity may occur mainly in the plant and penetration by R. similis. More recent not in the soil, with the plant selecting out observations also indicate that growth a microbial community conducive to plant promotion occurs (Figure 3). This could affect health. If this is the case, then examination plant tolerance to infection by increasing root of suppressive plants could yield isolates system biomass (Pocasangre unpublished and combinations that could be used data). There are indications that some fungal effectively to biologically enhance planting isolates directly parasitize nematodes in the material. This could be more productive soil (zum Felde 2000, Meneses et al. 2003, than the standard random method of “blind Cañizares, 2003). selection” of isolates from root tissue. Banana roots colonized by endophytes Selection of isolates from plants growing have recently been shown to have in suppressive soils might also insure that nematode repellent activity toward R. similis Figure 3. Effect of endophytic fungi on plant biologically enhanced plants have in planta growth promotion: plants inoculated with (Vu et al. 2005). This research has also suppressiveness that gives both short and Trichodema atroviride (right) and non inoculated demonstrated that some isolates are control plant (left). long term management. able to induce systemic resistance to the nematode. A number of fungi have been shown to produce toxic metabolites in vitro. This is not considered important under field conditions where nutrients are at a minimum and microbial competition high. The results demonstrate that each endophytic isolate may have a different mode of action and must be examined individually for this factor. In addition, the large spectrum of activity forms indicates that multiple-isolate- inoculants may be more successful in producing higher levels of control and long- term control by targeting multiple sites in the nematode’s life cycle. The use of biological enhancement in the field on a commercial basis is dependent on a number of factors: 1) efficacy;

28 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 29 2) mode of action; 3) durability of control; y abundancia nematodos en plantaciones de banano y 4) environmental concerns; 5) economics of plátano en la parte baja de los territorios indígenas de Talamanca. Agroforesteria de las América 10 (37-38): production and 6) registration requirements. 59-62. Commercial companies producing tissue Niere B.I., P.R. Speijer, C.S. Gold & R.A Sikora. 1998. culture plantlets on a large scale could use Fungal endophytes from bananas for the biocontrol of this technology. Radopholus similis. Pp. 313-318 in Proceedings of the Banana IPM Meeting. Nelspruit, South Africa. For biological enhancement to become a Pocasangre L. 2000. Biological enhancement of banana useful management tool more research is tissue culture plantlets with endophytic fungi for the needed in the following areas: 1) testing isolates control of the burrowing nematode Radopholus similis for plant pathogenicity using Vegetative- and Panama disease (Fusarium oxysporum f. sp. cubense). PhD thesis, University of Bonn, Germany. Compatibility Standards; 2) molecular analysis Pocasangre L.E., R.A. Sikora, V. Vilich & R.-P. Schuster. to determine their relationships to all endemic 2000. Survey of banana endophytic fungi from Central fungal populations; 3) production characteristics America and screening for biological control of i.e. fermentation efficacy, storage, formulation; Radopholus similis. Acta Horticulturae 531:283-290. Pocasangre L.E., A. zum Felde, A. Meneses, C. 4) multiple inoculants to mimic in planta Cañizares, A.S. Riveros, F.E. Rosales & R.A. Sikora. suppressiveness; 5) multi-cycle control efficacy; 2004. Manejo alternativo de fitonematodos en banano 6) control of other nematodes and diseases as y plátano. Pp.106-112 in Memorias, XVI Reunion well as weevils and 7) presence of isolates with Internacional de ACORBAT, Oaxaca, México. significant growth promotion activity. Pyrowolakis A., A. Westphal, R.A. Sikora & J.O. Becker. 2002. Identification of root-knot nematode suppressive soils. Applied soil Ecology 19:51-56. References Schuster R.-P., R. A. Sikora & N. Amin. 1995. Potential Alabouvette C., F. Roussel & J. Louvet. 1979. of endophytic fungi for the biological control of plant Characteristics of Fusarium wilt-suppressive soils and parasitic nematodes. Communications in Applied prospects for their utilization in biological control. Pp. Biological Sciences 60:1047-1052. 165-182 in Soil-Borne Plant Pathogens (B. Schippers and W. Gams, eds). Academic Press, London. Sikora R.A. 1992. Management of the antagonistic potential in agricultural ecosystems for the biological Amin N. 1994. Untersuchungen über die Bedeutung endophytischer Pilze für die biologische Bekämpfung control of plant parasitic nematodes. Annual Review of des wandernden Endoparasiten Radopholus similis Phytopathology 30:245-270. (Cobb) Thorne an Bananen. PhD thesis, University of Sikora R. A., J. Starr & J. Bridge. 2005. Management Bonn, Germany. practices: an overview of integrated nematode Baker K.F.& R.J. Cook. 1974. Biological control of management technologies. Pp. 793-825 in Plant plant pathogens. W. H. Freeman and Company, San parasitic nematodes in tropical and subtropical Francisco. 433pp. agriculture (M. Luc, R.A. Sikora & J. Bridge, eds) 2nd Cañizares C. 2003. Estudio sobre poblaciones de hongos Edition. CAB International, Wallingford, UK. endofiticos provenientes de suelos supresivos al Sikora R.A., B. Niere & J. Kimenju. 2003. Endophytic nematodo barrenador Radopholus similis (cobb) thorne microbial biodiversity and plant nematode management en plantaciones comerciales de platano en la zona de in African agriculture. Pp. 179-192 in Biological control Talamanca, Costa Rica. Tesis Maestría, CATIE. 94pp. in IPM systems in Africa. (P. Neuenschwander, Gold S.C., C. Nankinga, B. Niere & I. Maestrie Godonou. C. Borgemeister and J. Langewald, eds). CAB 2003. IPM of banana weevil in Africa with emphasis International, Wallingford, UK. on microbial control. Pp. 243-257 in Biological Vilich V. & R.A. Sikora. 1998. Diversity in Soil-Borne control in IPM systems in Africa (P. Neuenschwander, Microbial Communities: A Tool for Biological System C. Borgemeister and J. Langewald, eds). CAB Management of Root Health. Pp 1-15 in Plant-Microbe International, Wallingford, UK. Interactions and Biological Control (G.J. Boland & L.D. Griesbach M. 1999. Occurrence of mutualistic fungal Kuykendall, eds). Marcel Dekker Inc., New York, USA. endophytes in bananas (Musa spp.) and their potential Vu T.T., R.A. Sikora & R. Hauschild. 2005. Endophytic as biocontrol agents of the banana weevil Cosmopolites Fusarium strains induce systemic resistance against sordidus (Germar) (Coleopotera: Curculionidae) in Radopholus similis penetration into banana roots. Uganda. PhD thesis, University of Bonn, Germany. Nematologica (In review). Huber D.M. & R.W. Schneider. 1982. The description Weller D. 1988. Biological control of soilborne plant and occurrence of suppressive soils. Pp. 1-8 in pathogens in the rhizosphere with bacteria. Annual Suppressive soils and plant disease (R. W. Schneider, Richard A. Sikora works at the ed.). American Phytopathological Society Press. St. Review of Phytopathology 26:379-407. Paul, Minnesota. zum Felde A. 2002. Screening of endophytic fungi from Soil Ecosystem Phytopathology Jaime-Vega M.C. & A.S. Rodriguez Romero. 2004. Uso banana (Musa spp.) for antagonistic effects towards and Nematology, Institute for de micorrizas en banano: Logros y perspectivas. the burrowing nematode Radopholus similis ( Cobbb) Plant Diseases, University of Pp.143-160 in Memorias, XVI Reunion Internacional de Thorne. MSc thesis, University of Bonn, Germany. Bonn, Nussallee 9, ACORBAT, Oaxaca, México. zum Felde A., L.E. Pocasangre, R.A. Sikora. 2004. Kerry B.R., D.H. Crump & L.A. Mullen. 1982. Studies of Use of microbial communities inside suppressive 53115 Bonn, Germany, the cereal cyst nematode, Heterodera avenae, under banana plants to increase biocontrol of the burrowing and Luis E. Pocasangre at the continuous cereals, 1974-1978. I. Plant growth and nematode, Radopholus similis in Proceedings of INIBAP regional Office for Latin nematode multiplication. Annals of Applied Biology Workshop on Banana Root Systems: towards a better America and the Caribbean, 100:477-87. understanding for its productive management, 3-5 Nov. Meneses A., L.E. Pocasangre, E. Somarriba, A. Riveros 2003, San Jose, Costa Rica (D. W. Turner and F. E. Apartado Postal 60-7170- & F. Rosales. 2003. Diversidad de hongos endofiticos Rosales, eds). (In press) CATIE, Turrialba, Costa Rica

28 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 29 Marketing Partnership and networking in the tropical fruit industry: the experience of the International Tropical Fruits Network Khairuddin Tahir

lobalization is teaching us many are cooperating in order to better compete valuable lessons, if we care to learn with others. It is still possible to create a win- G from these lessons. Those who are win situation for everybody, as long as we not ready to learn or are too slow to adapt are not blinded by immediate and short-term to this wave of change may find themselves benefits. at a disadvantage, or worse, in perpetual TFNet’s membership, which consists of frustration, not knowing what hit them and governments, NGOs, private entrepreneurs why. Governments are working hard to and professional individuals with diverse position their economy to face the new rules interests in tropical fruit production, of global competition. In turn, businesses processing, consumption, marketing and need to make radical adjustments if they international trade, constitutes a rich want to survive and prosper. Organizations resource. The challenge for TFNet is to play also have to reinvent themselves in order to an effective “linking or networking” role and stay relevant. at the same time provide an independent At the international level, standards for platform where stakeholders of the tropical participating in the global trade regime often fruit industry can interact and articulate their change and become harder to achieve. needs and concerns, and, more importantly, The goal posts seem to keep moving in find solutions together. an increasingly non-level playing field. The Obviously, fostering networking and mantra of the market place is faster, cheaper, forging partnership has become one of better and safer. To play this globalization TFNet’s core businesses and primary game one has to comply with the rules or run activities. It is not our wish or intention to the risk of being left behind. be an exclusive club and we cannot afford to be a charitable organization, given our Dynamic business environment limited resources. Although categorized as Becoming savvy in information and commu- a not-for-profit international organization, we nication technologies (ICT) is necessary but need to generate income for the operations not sufficient for success. One must also of TFNet’s lean secretariat and to service our be creative and innovative in packaging members. TFNet is open to collaborating ideas, tools and approaches into viable and with parties, especially our members, who sustainable integrated systems. share our objectives, goals and aspirations, The International Tropical Fruits Network as can be seen from the various projects (TFNet), established four years ago, has to implemented with and for our members. operate in the challenging, and sometimes ruthless, environment of the agriculture Clientele sector, in which the players are numerous Let us move on to what really matters, and the resources limited. We often get the i.e. serving our clientele, which in our impression that we are in a “dog-eat-dog” case includes our members and small- situation, where the mighty and powerful scale farmers, small and medium-scale take on the new and small players, drive entrepreneurs, traders, exporters, pro- them into submission and eventually cessors, etc. We believe that farmers, eliminate competitors. regardless of whether they are in Belgium, Fortunately, the laws of nature seem Bolivia or Bangladesh, are basically the balanced and kind to us. We found same and have the same aspirations and many people and organizations willing to expectations to better their livelihood and collaborate, network and form strategic quality of life for themselves and their partnerships with TFNet, especially among children. Like people in other businesses, our own members, now numbering 55. We they have to live with fluctuating harvests, or

30 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 31 revenues, and they sometimes suffer losses governments and international organizations, due to natural calamities or to other people’s among them: decisions that are beyond their control or • Slow decision making due to multilevel influence. The difference between these bureaucratic processes, may take 2 to 5 years farmers, depending on which country they for project approval and implementation; live, may lie in their resource endowment • Competing with the private sector in certain and to some extent in the support or businesses and duplicating the functions of incentives they get from their governments, others; especially during times of natural calamity • Lack of flexibility in project design and and economic turbulence. implementation; When setting up partnerships and projects • Preoccupation with their internal programmes with its clientele or a rural community, the and activities leaving little resources and main concern of an organization like TFNet time to collaborate with others; is to listen diligently and patiently, and then to • Lack of focus and specialization. evaluate its client’s needs (versus its wants), resource endowment, knowledge and NGOs and the private sector technology gaps, infrastructual deficiency, Generally, non-governmental organizations etc. Those involved in rural development (NGOs) are good partners in networks as know this and have developed a they tend to be focused and specialized comprehensive checklist. The next step and not too bureaucratic. NGOs tend to be is how partners can be a catalyst and flexible, forward-looking and adaptive in their provide the incentives and appropriate relationship with partners. However, some mechanisms that will push the clientele, NGOs lack accountability or are perceived or rural community, to higher levels of as having radical views on some mainstream productivity, or from subsistence farming issues. Some NGOs are also suspicious of into a market economy. Farmers, like all of other NGOs when they compete for similar us, are rational economic beings. They are resources, especially funds, clientele or not culturally destined to remain poor and target groups. the role of partners is to empower them so Small and medium-scale entrepreneurs that they can redeem their dignity through (SMEs) are excellent partners because participatory income generating projects. they tend to get “squeezed” between public companies and multinational Governments and international corporations and, as a result, are willing organizations to work with autonomous bodies, like Governments, international organizations, TFNet. SMEs are innovative and ready to including regional ones, and specialized UN try new ideas to improve their revenues agencies, are important partners in networks and market share (Figure 1). They are as they provide valuable data, information, also willing to share their technical and technical and financial resources. On the market knowledge and information with international scene, these bodies use various partners as leverage for expanding and multilateral platforms to provide guidance, improving their business. TFNet has direction and coordination to ensure an had positive experiences working in orderly and sustainable development of partnership with SMEs. various aspects of life. In many developing Larger corporations are also open to countries, governments are major players at partnerships, often to enhance their image the national level and tend to dominate rural as good corporate citizens, especially development activities. This is often the only when their products or services are under channel for partners to get involved in rural public scrutiny. However, they tend to community projects. favour partnerships with governments, Both government and international and to a lesser extent with SMEs and organizations are continuously undergoing NGOs. But in a highly competitive global structural and functional changes, environment, business relationships are consolidating their activities and positioning rapidly changing as large corporations themselves to meet new challenges and increasingly outsource jobs to efficient demands. However, many factors have been SMEs in order to cut costs and deliver identified that may affect partnership with their goods and services on time. This

30 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 31 • Creativity and innovation • Patience and resilience • Application of ICT and knowledge management • Win-win situation. Conclusion Obviously, no single body or organization, including government, can pretend to monopolise the task of bringing about socio- economic changes to a particular sector or community. Partnership and networking become essential functions in efforts to mobilize resources for a common or noble cause. At the same time, one must not assume that partnership and networking are just a matter

John Jagwe of common sense. On the contrary, they need to be learned, experienced, promoted Figure 1. Small-scale entrepreneurs – like Mrs partnership is already prevalent in the food and nurtured. Partnership and networking Olomi whose company, Banana Investments supply chain, especially in the logistics, trans- Ltd. in Arusha, Tanzania, now hires 70 fulltime go beyond the sharing of knowledge and employees – are innovative and ready to try portation and packaging sectors. technical competency, and involve the new ideas to improve their revenues and fusion of cultures and work ethics among market share. Ingredients for success multidisciplinary stakeholders. Partnership How can partnership and networking be and networking result in having to redefine established, fostered and sustained? From one’s worldview and value system. TFNet’s experience, the following factors For too long, many promises have been contribute to the success of a partnership made to farmers to improve their livelihood and a network: and they have been patient with us despite • Shared vision and goals numerous shortcomings. To avoid repeating • Trust past mistakes, fresh and creative ideas are Khairuddin Tahir is the CEO • Leadership needed to ensure successful partnerships of International Tropical Fruits • Transparency and accountability and networking. It is imperative that we Network (TFNet), 43400 • Being accommodating, flexible and think out-of-the-box and try to do things Serdang, Selangor, Malaysia adaptive differently.

Focus on the Musa congress Highlights on the First International congress on Musa

The first two days of the First International Advances in breeding Congress on Musa featured presentations The first strategy was pioneered by the from breeders, geneticists and molecular Fundación Hondureña de Investigación scientists with a session on genetic Agrícola (FHIA). It involves crossing a th resources and improvement and the 4 susceptible triploid cultivar with a diploid International symposium on the molecular that is disease resistant in order to produce and cellular biology of bananas. Kodjo a resistant tetraploid. This is possible when Tomekpe, head breeder and director the female parent transmits the totality of of the Centre Africain de Recherches her triploid genome, by not undergoing sur Bananiers et Plantains (CARBAP) meiosis, and the male parent contributes, in opened the Congress with a review on his haploid genome that has been through conventional breeding strategies (see the normal process of meiosis, the desired article on p. 2), their achievements but resistance genes. But since the male parent also their limitations. provides much more than resistance genes,

32 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 33 the resulting tetraploid hybrid is not an exact crossing triploids with diploid hybrids bred for replica of the triploid cultivar the breeders are parthenocarpy and higher male fertility and trying to improve. As Tomepke remarked, the disease resistance. Some of the cultivars impact of the 3X x 2X strategy is limited they are trying to improve are ‘Karpooravalli’ by the low number of triploid cultivars (‘‘, ABB), ‘Red Banana’ (AAA), possessing the level of female fertility that ‘Rasthali’ (Silk, AAB), ‘Nendran’ (AAB) and would allow their use in crossings. Moreover, ‘Poovan‘ (Mysore, AAB). They are also the few that are fertile enough tend to be experimenting with gamma radiation and interspecific hybrids of Musa acuminata chemical mutagens to produce improved and and as such are mutants and with colchicine and oryzalin likely to contain activable sequences of the to double the number of chromosomes. banana streak virus (BSV) integrated in the Tetraploids have been generated from four balbisiana genome. local diploid cultivars of the AA and AB However, as the presentations made by genomic groups and are currently being the other breeders present at the Congress tested in the field. have shown, the BSV problem has not Doubling the number of chromosomes is stopped them from trying to improve the also the starting point of a strategy adopted local cultivars that contain the B genome by by the Centre de coopération internationale using variants of the conventional strategy. en recherche agronomique pour le déve- Sebastiao de Oliveira e Silva reported that, loppement (Cirad) and CARBAP. The in Brazil, the Empresa Brasileira de Pesquisa scheme starts off with diploids, wild or Agropecuaria (Embrapa) has developed improved. The chromosome number of several promising hybrids, among them improved diploids is doubled by treating ‘Tropical’ (AAAB), which resembles ‘Maça’ them with colchicine. The induced tetraploid (AAB), a Silk cultivar, and ‘Preciosa’ (AAAB), is then crossed with another diploid parent to which has characteristics similar to those of produce a triploid hybrid. Cirad has used this ‘Pacovan’ (AAB), a Pome cultivar. method to develop triploid dessert banana, At the International Institute of Tropical whereas CARBAP has used it to produce Agriculture (IITA), tetraploids obtained from AAA plantains by inducing tetraploidy in a crossing a triploid with a resistant diploid diploid Musa acuminata spp. banksii with were crossed again with improved diploids plantain-like characteristics. As Tomekpe to produce secondary triploids. Six triploid noted in his keynote address, the success hybrids have been produced this way to of this strategy relies on a clever choice of improve the locally important group of parents guided by a good knowledge of their East African highland bananas, reported genetic structure, which has increased with Michael Pillay, the breeder in charge of the the development of molecular tools. IITA breeding programme in Uganda. Their agronomic performance will be evaluated in The banana family tree the field by farmers. The six hybrids being Molecular techniques are also used to tested all have the same yellow flesh as the study the genealogy of Musa cultivars. In cultivars but other hybrids with good disease her review on molecular markers, Françoise and pest resistance have a white flesh that Carreel of Cirad in Guadeloupe explained may not be accepted by consumers and is how scientists have taken advantage of probably associated with a lower level of the maternal transmission of chloroplast Vitamin A precursors. The latter are being DNA and paternal transmission of mito- crossed with yellow-fleshed accessions from chondrial DNA to establish the lineages of Papua New Guinea to improve their color. monospecific and interspecific cultivars. The As a secondary centre of banana diversity, speaker also reminded the audience that M. India has no shortage of cultivars that acuminata and Musa balbisiana are not the need a helping hand to resist diseases, only species that have hybridized to produce which in this part of the world are mainly cultivars. Molecular studies have confirmed, Sigatoka disease caused by Mycosphaerella and in some cases revealed, the presence musicola, Fusarium wilt and the burrowing of the australimusa (T) and schizocarpa (S) nematode Radopholus similis. Dr Kumar genomes, a finding that should eventually from the Tamil Nadu Agricultural University lead to the reclassification of certain in southern India, presented results from accessions.

32 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 33 Even when it comes to M. acuminata and into the banana genome (some 500-600 M. balbisiana, however, we rarely know Mbp) were presented by Chris Town, from which variants of their genomes played The Institute for Genomic Research (TIGR), a role in the evolution of cultivars. Hugo a non-profit research institution in the USA, Volkaert from the Center for Agricultural and Rita Aert from KULeuven. Biotechnology in Thailand presented the The scientists at TIGR sequenced and results of a study done in collaboration annotated 13 BAC clones, totaling around with Sasivimon Swangpol from Mahidol 1.4 Mb, from the ‘Calcutta 4’ BAC library. University in Bangkok, Rachel Sotto from The gene density was high and generally the Institute of Plant Breeding, in the comparable to that seen in Arabidopsis Philippines and Tosak Seelanan from and rice (one gene every 4-5 kb). Of the Chulalongkorn University in Bangkok, annotated genes that had a high quality Thailand. After analysing the chloroplast match with genes of another species, 78 DNA of Thai cultivars, they concluded that were with Arabidopsis genes and 59 with three M. acuminata subspecies (malaccensis, rice genes. Based on the content and banksii, and zebrina) accounted for the distribution of glutamine and cytosine along ancestral maternal lineages in AA, AAA, the coding sequence, 175 genes were more AAB, AB and ABB hybrids. The results also Arabidopsis-like whereas only 33 were more indicate that AAA cultivars have a hybrid rice-like. origin and that the cultivars in the Namwa Meanwhile at KULeuven, Rita Aert and group have a single BB maternal origin, her collaborators randomly chose two BAC probably introduced from the Pacific Islands. clones from the M. acuminata ‘Calcutta 4’ The speaker suggested designating some BAC library. The analysis of the first BAC ABB cultivars as BBA to better reflect their (82 723 bp) revealed 12 putative proteins, maternal lineage. representing a gene density of one gene A first peek into the genome per 6.9 kb. Only 7 coding regions were discovered in the second BAC (73 268 bp), for Martin Dickman from the University th an overall gene density of one gene per 10.5 of Nebraska in the USA opened the 4 kb. The gene organization of these clones International symposium on molecular and resembles the sequences of Gramineae cellular biology with a talk on the role of model genomes, where genes are clustered in plants in improving bananas through genetic gene-rich regions separated by gene-poor transformation and on how programmed cell DNA containing transposable elements. By death can be used to engineer resistance contrast, the genes on chromosomes 1 and to pathogens (see article on p. 6). As the 4 of the Arabidopsis and rice genomes are speaker pointed out, Arabidopsis – the fairly evenly distributed. first plant to have its genome sequenced because of the smallness of its genome Tracking BSV and the ease with which the plant can be The publicly available BAC libraries are manipulated in the lab – is a dicotyledon and also used by researchers from Cirad, as a result it was thought that the banana, a Centro de Investigación y de Estudios monocotyledon, would be closer genetically Avanzados (CINVESTAV), National Institute to rice, another ‘monocot’ whose genome is of Agrobiological Sciences (NIAS) and almost completely sequenced. If the results the Queensland Department of Primary presented at the Congress are confirmed, Industries (QDPI) to study the mechanisms the banana may not be as close to rice as leading to the activation of the banana streak expected. virus (BSV) integrated in the nuclear genome Researchers working on the genome can of Musa cultivars containing the so-called B sift through the BAC libraries constructed genome inherited from M. balbisiana. Strong from the genomes of M. acuminata (two experimental evidence suggests that some libraries of ‘Calcutta 4’) and M. balbisiana of these integrated sequences, which never (‘Pisang klutuk wulung’) that have been result in infections in M. balbisiana, can be made publicly available by the Global Musa expressed and produce episomal forms of Genomics Consortium (a BAC library of the virus that give rise to infections under ‘Grande naine’ developed by Cirad should stress conditions in hybrids, including be made available soon). The first glimpses the hybridization process itself. This

34 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 35 phenomenon represents a serious limitation to the creation of Musa hybrids containing the A and B genomes and to their diffusion. Pierre-Yves Teycheney from Cirad showed how his team used the complete genomes of four BSV strains (BSV-Ol ‘Obino l’ewai’, BSV-Gf ‘Gold finger’, BSV-Im ‘Imove’ and BSV-Mys ‘Mysore’) as probes to screen BAC libraries for the presence of integrated viral sequences in chromosomes of the A and B genomes. In the M. balbisiana ‘Pisang klutuk wulung’ BAC library, they identified 10 BAC clones positive for BSV-Ol, 9 BAC clones positive for BSV-Gf and 24 BAC clones positive for BSV-Im. Screening of

the ‘Calcutta 4’ and ‘Grande naine’ BAC Xu Linbing libraries revealed no BSV sequences. The BAC clones containing BSV sequences given by Jean Carlier of Cirad and focused on Opening ceremony of the First International Congress on Musa held in Penang in July. were further characterized by BAC-end the genetic population structure of one of the sequencing and RFLP fingerprinting and the most devastating of those threats, the fungus BAC clones containing BSV-Ol or BSV-Gf Mycosphaerella fijiensis, in order to develop sequences were completely sequenced. sustainable and effective management As part of this research project conducted strategies to control the disease it causes at Cirad, Gandra Saiprasad from the Indian (see article on p. 17). Institute of Horticulture Research tested As Ploetz pointed out in his keynote, as various stress factors, such as an antibiotic a perennial, banana needs long-term pest (hygromycin), a polyamine (spermidine), a management solutions but few of the existing demethylating agent (5-Aza cytidine) and strategies are sustainable. Of course, a lot heat shock (60°C for 1 h) in the hope of depends on the problem at hand. In another triggering the expression of some integrated talk on the biological control of Fusarium wilt, sequences. The episomal form of BSV in Ploetz concluded, somewhat discouragingly stressed plants of cv. ‘Penkelon’ (AAB) was for the speakers who were presenting talks checked by PCR. It turned out that BSV on the biocontrol of Fusarium wilt, that there activation was very random, with only 2-4 % is no evidence that biological control is of the plants treated with an antibiotic and a effective against Fusarium wilt in the field. demethylating agent developing an infection Fusarium wilt is an especially difficult target after 72 hours. for biocontrol, said Ploetz. The soil in which Suppressive subtractive hybridization the pathogen resides complicates protection (SSH) libraries were constructed by selecting of infection sites, naturally suppressive soils the RNA that was not common to the BSV are rare and the vascular location of the activated and BSV non-activated plants. infection protects the pathogen from many Four SSH libraries, with about 1500-2000 potential biocontrol agents. Diverse microbes expressed sequence tags (ESTs) each, have been tested – arbuscular mycorrhizal have been constructed and will be used for fungi, Bacillus spp., pseudomonads, non- the isolation of host factors involved in BSV pathogenic endophytes and Trichoderma activation. spp. – but few of these studies have been conducted in the field. What has been more Pests and diseases commonly reported in journals is an in vitro BSV is only one of the many organisms inhibition of the pathogen or a disease associated with bananas. In his review of reduction in pot studies. When field studies the major diseases and pests of bananas, have been conducted, the results have been Randy Ploetz from the University of Florida disappointing. also covers the new threats and the ones The best result found in a refereed journal that might spell problems in the future (see is an 18% loss after 11 months, which article on p. 11). The other keynote address would amount to a cumulative loss of over to open the session on plant protection was 60% after 5 years. Given the nature of

34 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 35 the pathosystem, the speaker believes that its greatest impact when applied to tissue Fusarium wilt of banana will be difficult to culture plantlets. control with biological agents and wondered In a similar vein, Dirk de Waele from whether the resources spent on looking for KULeuven advocated inoculating with biocontrol solutions would not be better arbuscular mycorrhizal fungi (AMF) banana invested elsewhere. plantlets that are destined to be transplanted Biological control is one of the features of into nematode-infested soils. AMF are the International Banana Action Plan, which obligate symbionts that colonize the root Gert Kema of Plant Research International cortex of host plants. These fungi help the B.V. in the Netherlands announced at the plant acquire water and mineral nutrients Congress. The aim of the plan initiated by from the soil and in return obtain carbon as the Wageningen University and Research an energy source. In addition, AMF increase Centre is to reduce pesticide input in banana the ability of a plant to overcome abiotic and production by at least 50% over the coming biotic stresses and to reduce colonization by decade. The plan will focus on the control soil-borne pathogens, namely nematodes. of Mycosphaerella leaf spot diseases However, the magnitude of this response, and Radopholus similis and will address expressed as the relative mycorrhizal fundamental as well as applied questions. dependency (RMD), depends on the cultivar. It is divided into seven themes: 1) pathogen The higher the RMD, the greater the effect of genomics and genetics, 2) genetics and inoculating myccorrhiza. breeding for resistance, 3) epidemiology For small-scale farmers in places where and population genetics, 4) soil science, in vitro plantlets are not an option, Kim 5) biological control, 6) precision farming Jacobsen from the INIBAP regional office and disease management strategies and in Cameroon, is exploring cultural practices 7) extension and social impact programmes. to control nematodes in a project conducted in collaboration with IITA and KULeuven. Nematodes As a result of reduced land availability, In East Africa, nematodes seem to be fallow periods tend to be shorter and contributing to a shift from cooking bananas pest populations, including R. similis, are to the more tolerant dessert and beer increasing and bringing down yields. In her cultivars. Dany Coyne from IITA presented talk, she presented results on the efficiency some of the results from a project on of fallow and hot water treatments on nematode management in Uganda using ‘Essong’ (AAB, French) and ‘Ebang’ (AAB, mutualistic endophyte fungi. The project False Horn plantain). is done in collaboration with the Uganda Jacobsen tested two fallow periods, long National Agricultural Research Organization, fallow (15 years) and short fallow (4 years), Makerere University, Pretoria University in the effect of adding, or not adding, fertilizers South Africa and the University of Bonn in and of treating, or not treating, suckers with Germany. hot water (20 min at 52°C). Sampling was Endophytes are common asymptomatic done at 15 and 21 months after planting to parasites that cause no damage to the host coincide with the flowering/harvest of the first plant but can suppress or repel potential production cycle and 6 months later. After 15 parasites. In Uganda, the most frequently months, the number of nematodes was isolated endophytes are avirulent strains significantly lower on the hot water-treated of Fusarium oxysporum. For this study, plants for both fallow systems and the root isolates of F. oxysporum from corms and system was healthier, but after 21 months, roots were screened for in vitro activity the increase in nematode number in the against the burrowing nematode, R. similis. short fallow plots outweighed these benefits. The multiplication of the nematode was The best banana yields in the short fallow suppressed in tissue culture banana plots were not as good as the worst results plants and control of the population in the long fallow system. Although farmers was still observed seven months after are better off using long fallow, they may not inoculation. The speaker concluded that be able to practice it for much longer. Unless fungal endophytes could provide a tool for short fallow cultural practices are improved, nematode management, which should have their yields are bound to suffer.

36 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 37 Finally, Omolara Rotimi from the Federal replace in rural areas the potassium and University of Technology in Nigeria talked nitrogen contained in the bananas shipped about the effect of mulching on the to Kampala. susceptibility of ‘Agbagba’ to nematodes. Although the management and She compared heavily mulched and maintenance of soil fertility is critical to non-mulched management regimes. The ensure the sustainability of production nematode population consisted of systems, the topic is just starting to attract Helicotylenchus dihystera, Helicotylenchus the attention of banana scientists, hence the multicinctus, Hoplolaimus pararobustus, relatively small number of talks presented Meloidogyne spp. and R. similis. In the at the Congress, many of which reported absence of nematodes, the yield in mulched research that had been published in recent plots was 8.1 tonnes per hectare compared issues of INFOMUSA. Clearly, this is an area to 3.6 tonnes per hectare in the non-mulched that deserves future investment and effort in plots. In the presence of nematodes, yield the future. reduction was 46% in heavily mulched plots compared to 54% in the non-mulched plants. Nurturing enterprises and However, a higher incidence of toppling improving livelihoods (23%) was observed in mulched plots, In the fourth session of the Congress, compared to 16 % in the non-mulched ones. on postharvest and processing for the Evidently, there are complex interactions diversification of incomes, the participants involved in mulching systems that need to were treated to talks on enterprise deve- be resolved. lopment, an often overlooked topic, despite Propping up production systems its importance in providing farmers with the means and incentives to invest in soil fertility Richard Sikora from the University of Bonn and improved crop protection. Charles in Germany and Piet Van Asten from IITA- Staver from INIBAP, opened the session ESARC in Uganda, opened the third session with a talk on a NORAD-financed project in of the Congress on sustaining the natural which he worked before joining INIBAP (see resource base in Musa cropping systems. Sikora revisited the topic of biological control next issue of INFOMUSA). Set in Nicaragua, but from the point of view of the microbial the project aimed to develop a participatory communities that live in the rhizosphere and group learning approach for agro-ecological are important for root health and growth (see pest and crop management in Musa. page 25). Specific fungi, and probably even Resource-limited Nicaraguan farmers tend bacteria, have health-promoting abilities to cultivate bananas with minimal inputs that are believed to suppress pests or and labour. This low-risk strategy is often diseases when the microbial communities complicated by an inadequate management are established and functioning properly. of pests and diseases that leads to reduced The speaker explored whether they can bunch size and fewer production cycles. be enlisted in the fight against pests and With commercial pesticides being beyond diseases. the financial reach of most farmers, In his talk (see p. 20), Van Asten highlighted pest management strategies have been a nutrient deficit in the smallholder banana developed that are consistent with the low farms of East Africa. With the urban risk/low input strategy that makes Musa population steadily growing, banana production a useful commercial and home products and their nutrients are increasingly consumption complement in rural areas. exported from farms to urban centers, a In the other keynote address (see p. 30), situation that is exacerbated by the fact that Khairuddin Hatir, the CEO of the International East African banana farmers seldom use Tropical Fruits Network (TFNet), explained mineral fertilizers to replenish soil nutrients. the network’s mandate as promoting the Instead, they rely mainly on manure and crop sustainable development of the production, residues, causing further soil fertility decline consumption, processing, marketing and in annually cropped fields. In Uganda, for international trade of the tropical and example, the speaker estimates that at the sub-tropical fruit sector. According to the current mineral fertilizer prices, it would speaker, the key factors instrumental in cost over 2 million US dollars annually to fostering lasting partnerships are leadership,

36 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 37 good governance, transparency, knowledge pointed out that there are many yellow- and management, creativity and empowerment. orange-fleshed bananas in other countries Lois Englberger’s talk on carotenoid – such as ‘Pisang raja’, ‘Pisang berangan’, levels in cultivars from Micronesia (see ‘Pisang mas’, ‘Champa’ in Bangladesh, INFOMUSA 12(2):2-5) drew a lot of ‘Nendran’ in India and ‘Lakatan’ in the interest, not only from the participants but Philippines – which could have an impact also from the media. Her data show that on eliminating VAD and improving general some traditional varieties contain enough health. provitamin A carotenoids at realistic Finally, a number of speakers from Africa consumption levels to prevent Vitamin and Asia presented national and local A deficiency (VAD), a major cause of initiatives to foster the development of debilitating health problems in developing banana enterprises. The abstracts of the oral countries and a significant contributor to presentations and posters are available on infant and maternal mortality. Lois also INIBAP’s website at www.inibap.org.

Focus on bacterial wilt How can the advance of banana xanthomonas wilt be halted?

Since its detection in central Uganda in on measures that are designed to reduce 2001 (Tushemereirwe et al. 2003), banana disease infection and to rehabilitate areas xanthomonas wilt disease (BXW, also that are already infected (i.e. management), referred to in Uganda as banana bacterial and to reduce or prevent the spread of wilt) has spread to at least 21 districts disease to areas that are not yet infected throughout the eastern, central and north- (i.e. containment). Experience with these western parts of the country, probably diseases shows that once they have become mediated by airborne (most likely insect) established in smallholder banana cropping vector(s). Although the distribution within systems, then control is very difficult and these districts is still localised and patchy, the disease is rapidly filling in the gaps. It is also moving south and westwards towards some of the most important banana growing areas in the country that are not yet affected. All of the commonly grown genotypes are succumbing to this new disease, which destroys the fruit bunches and can reduce yields to zero, threatening the livelihoods of millions of people. An outbreak has also recently been confirmed in the North Kivu region of the Democratic Republic of Congo (see Musanews), and the disease is poised to enter Rwanda, Kenya and neighbouring countries. There is increasing public awareness of the plight of those who have already suffered severe hardship from the disease and concern for those at risk. BXW has many similarities to bacterial wilts of banana in other parts of the world (Moko, blood, bugtok diseases) that are caused Simon Eden-Green by Ralstonia (formerly Pseudomonas) Figure 1. Affected mats do not always die, so once the disease has solanacearum and closely related organisms become established in smallholder production systems, it is very (Thwaites et al. 2000). Control depends difficult to eradicate.

38 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 39 eradication effectively impossible (Figure 1). susceptible to insect transmission in other Farmers and consumers have to get used to banana bacterial wilt diseases (Buddenhagen massively reduced yields. Interventions in and Elsasser 1962). This suggests that, as these “zones of occupation” need to focus with these other diseases, airborne infection on helping farming communities to manage, via male flower parts is the main mechanism or learn to live with, the disease, including driving the current epidemic. Thus timely introducing alternative crops and food staples removal of the male bud should interrupt the and gaining their acceptance. This will be a transmission cycle and prevent the spread of daunting task in Uganda, emphasizing the the disease, especially if this can be done importance of containment. in those types that are considered to be at Disease containment depends on two greatest risk to infection via thus route. key actions: promptly removing sources Herein lies the main challenge for of inoculum; and reducing or eliminating controlling the epidemic in Uganda where opportunities for spread. These are mutually the ABB type ‘Pisang awak’, known locally reinforcing: the greatest degree of control as kayinja, is widely grown for the production will be obtained when infection sources of “”. At the margins of the are eliminated promptly and the risks of disease front, and throughout areas already transmission are reduced. Many sources of affected, kayinjas and other ABB types such infection are known or suspected for BXW, as ‘Bluggoe’ (Kivuvu) can be found with including standing infected plants, plant typical symptoms of inflorescence infection residues, contaminated soils and water, and (Figure 2). Farmers themselves have traded products (fruits, leaves and planting come to recognise that these are usually materials). The contribution these sources the first types to become infected. Control make to the spread of the disease depends options seem obvious enough – reduce on the survival of bacteria and the mode the rapid rate of spread by destroying, or at (and probability) of transmission. Although least debudding, the ABB types and then the relative importance of many of these concentrate on preventing other modes of factors is unknown, tentative conclusions spread (contaminated tools, infected plant about factors likely to be most important materials) and clean up areas already for disease containment can be drawn from infected. Unfortunately however, plots field observations on the behaviour of the disease in Uganda and from knowledge of other banana bacterial wilts. A remarkable feature of all these diseases is that infection appears to occur via the male bud, probably following transmission by flying insects that collect or feed on nectar and pollen. Although it is not known at present whether the same or similar insects are involved, this is a striking example of parallel evolution: at least three taxonomically distinct pathogens of banana appear to have evolved a similar mechanism of transmission on different continents. Fortunately, this also presents similar opportunities for controlling the spread of disease1. Observations at advancing disease fronts in Uganda suggest that transmission to the male bud is the primary means of spread. Not only are diseased buds often the first symptom to be observed but these are also most commonly seen on ABB banana types, which are known to be particularly Simon Eden-Green 1 See discussion forum at http://www.banana.go.ug/cgi-bin/ discus/discus.cgi Figure 2. Infected male bud.

38 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 39 of kayinjas are frequently neglected or at spread. The question, as yet inadequately best semi-cultivated and whilst harvesting untested, is how effective are such individual rights may be established by local courses of action. Can individual farmers, custom, ownership and responsibility for with fields of on average no more than maintenance is often obscure. Under these 1-2 ha, prevent the disease from becoming circumstances, it is understandably difficult established by debudding on such a small to persuade individual farmers to debud scale? At present, the experiments remain healthy plants or to cut down or destroy mats to be done but the stakes are high. If only a that have become diseased but may still small proportion of farmers were to succeed produce the occasional usable bunch of fruit by adopting such measures, then others – let alone to remove plots of kayinjas that would surely follow and “green islands” are not yet affected. Financial inducements would emerge amidst the surrounding or compensation are unlikely to be feasible devastation. The evidence is certainly given the magnitude and continuing nature encouraging: unconfirmed reports suggest of the problem, and the costs and logistics that some farmers have greatly reduced or involved. Can some form of community awareness and action succeed, perhaps even prevented the spread of disease in their backed by coercion or enforcement? And fields since adopting debudding, cutting out to what extent can individual farmers take infection and other phytosanitary measures. action to protect their own banana plantings As reported in this issue’s Musanews, it is for themselves? surely no accident that Dwarf Cavendish, Two broad approaches can be suggested: a variety with floral morphology resistant firstly, a series of cordons sanitaires at the to insect-borne infection, survives virtually margins or “disease fronts” of the epidemic, unscathed alongside diseased kayinjas involving intensive control measures in Ethiopia. Can it be coincidence that in including phytosanitation, eradication of the Congo, where inflorescence infection all diseased plants, debudding of healthy appears to be rare, the disease has so far ones, and strict controls on the movement spread slowly? of people and planting materials. This would Whilst prevention of airborne dispersal of require actions both within and in advance the bacteria between inflorescences may be of a diseased area in order to create a the most important means of controlling the “firebreak”, or zone of zero tolerance of primary spread of the disease, especially both sources of inoculum (diseased plants) between farms and villages, other modes of and infection courts (male buds). Given infection undoubtedly occur and are critical the difficulties of managing kayinjas, a to containment. The necessary measures high degree of community participation, can be summarised as follows: mobilisation and support would be required. • Intensive surveillance and reporting to The resources necessary to achieve identify the current disease distribution and this may be justified when the stakes presence of suspected new outbreaks; are particularly high, as for instance in • Prompt follow-up actions to investigate preventing further movement of the disease reports of new outbreaks and to take to the intensive banana cultivation areas in action to eradicate or neutralise them; southwest Uganda. Even so, it is difficult to Strict control on the movement of plant conceive of the high levels of adoption (and • materials from diseased to non-diseased Simon Eden-Green, enforcement) of control measures that are Consultant to the Banana likely to be necessary on the broad front over areas, especially planting materials; Bacterial Wilt Project at which the disease is progressing. • Availability and strict observance of Kawanda Agricultural The second approach depends on what phytosanitary practices, especially disin- Research station, Uganda individual farmers can do for themselves. fection of cultivation tools, footwear etc.; (funded by NARO and the Farmers may be able to do little to control • Strict control of infection, and preferably Gatsby Charitable sources of infection (and hence inoculum) total destruction, of ABB types at the Foundation, UK). that surround their own plants, but they can disease front; EG Consulting; 470 Lunsford take steps to prevent their bananas from • Strict enforcement of debudding of all types Lane, Larkfield, becoming infected through their own actions at, and in advance of, the disease front by Kent ME20 6JA, UK. (use of contaminated tools, footwear, planting breaking off (not cutting) the male buds as Email: [email protected] materials) and by preventing airborne soon as the last fruits have set.

40 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 41 References of Banana, Abaca and Enset (D.R. Jones, ed.). Wallingford, UK, CABI Publishing. Buddenhagen I.W. & T.A. Elsasser. 1962. An insect spread bacterial wilt epiphytotic of bluggoe banana. Tushemereirwe W., A. Kangire, J. Smith, F. Ssekiwoko, Nature 194:164-165. M. Nakyanzi, D. Kataama, C. Musiitwa, & R. Karyaija. Thwaites R., S.J. Eden-Green & R. Black. 2000. 2003. An outbreak of bacterial wilt on banana in Diseases caused by bacteria. Pp. 213-240 in Diseases Uganda. INFOMUSA 12(2):6-8.

Effect of soil compaction on the architecture of the Thesis banana root system growing in an andosol F. Lecompte

PhD thesis submitted in 2002 to the was almost strictly acropetal (from base to Institut National Agronomique Paris- apex). The density of root branching was Grignon and the Avignon Institut National less the further away from the base of the de Recherche Agronomique, France root and the smaller the diameter of the main Despite the coexistence of several banana root. Root senescence was not explicitly production systems in the West Indies, characterized, but is related to the duration mechanized monocultures remain important. of the growth phase of the root, which seems Heavy machinery, soil tillage and frequent proportional to its mean diameter. planting lead to the degradation of soil The impact of soil compaction on the structure and decreased soil fertility, while architecture of the root system was studied monoculture favors pests. Andosols are in pots (static compaction with an hydraulic very frequent in the traditional banana press) and in the field (dynamic compaction growing area of Guadeloupe and naturally with tractor wheels) to study the response of promote the development of the root system. the roots to pressures ranging from 50 kPa However the dynamics of soil colonization to1200 kPa. A slight decrease in the growth of by banana plants remain largely unknown and as a result cultural practices cannot be dry matter in shoots was observed when the adapted to the uptake and anchoring abilities soil was highly compacted. Only the growth of the roots. Experiments were conducted to of the large roots was affected by a lower characterize the architecture of the banana soil macroporosity: an 8% reduction in total root system three months after plantation in porosity (corresponding to a 65% reduction an andosol. in air filled spaces) reduced their growth rate Experiments in rhizotrons, containers, by 50%. A multiple linear regression between and in the field helped determine the growth rate and three factors (diameter at parameters pertaining to four main functions: the apex, soil porosity and total degree days) root emission, root growth, root branching accounted for 92% of the observed variance. and senescence. Root emission was Soil compaction increased the death rate fairly similar to what is observed in other of primary roots by a factor of 4 but did not monocotyledons, like maize and rice, and globally affect root trajectory, which tends to was correlated with shoot development. The be horizontal. Roots growing in compacted diameter at the root apex increased between soils had a more tortuous trajectory. planting to emission and changed over the life of the root. Two original methods based A model of the architecture of the on static morphological observations were banana root system was built to simulate used to determine the in situ root growth the development of the root system under rates. The root growth rates ranged from various soil conditions. Once validated, this 0.1 cm/day in quaternary roots to 3.5 cm/day model could help understand the effect of in primary roots and were closely related to various mechanization scenarios on root the diameter at the apex. Root branching absorption and the stability of the plant.

40 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 41 Thesis Vitamin content of unripe bananas and derived products Maria Teresa Borges

PhD thesis submitted to Universidade pulp was also determined and compared Estadual de Campinas, Unicamp, SP, with the one of similar products (potato Brazil, November 2003 nhoque and integral bread). A sensory test was also conducted with untrained panelists Brazil, one of the largest producers of to evaluate the acceptance of these foods. bananas, is also one of the countries with the Unripe fruits of ‘Nanicão’ and ‘Prata’ had highest proportion of waste. The use of the respectively 0.57 and 0.84mg/100g of B , 1.4 green bananas offers a way to minimize this 1 and 1.1mg/100g of B6, 135 and 104μg/100g problem. The objective of this work was to of folic acid, 17.6 and 20.2mg/100g of LAA, evaluate the vitamin content of bananas with 6.1 and 5.8mg/100g of DHAA, and 1073 and the aim of improving the uses of the fruit. 441μg/100g of β-carotene. The levels in the The levels of the vitamin B complex (PP, mature fruits were respectively 0.63 and B , B , B and folic acid), pro-vitamin A (β- 1 2 6 1.08mg/100g of B1, 0.75 and 0.63mg/100g carotene) and vitamin C (L-ascorbic acid of B6, 12.4 and 19.2mg/100g of LAA, 3.6 (LAA) and dehydroascorbic acid (DHAA)) and 4.5mg/100g of DHAA, and 1682 and were measured in the fruits of the cultivars 1072μg/100g of β-carotene. No vitamin B2 ‘Nanicão’ and ‘Prata’ from the orchards of the was found in the samples analysed. The Taperão Farm in the town of Brotas, from the vitamin levels in the products made from emergence of the fruit to senescence, and unripe banana pulp were similar to the ones with and without induction of the ripening in the fruits and the other products, except process. The vitamin content of banana for the various forms of vitamin C. The bread and nhoque* made with unripe banana acceptance sensory tests suggested some modifications to be made in the recipes *Gnocchi proposed to the panel.

Musa News Poster competition

A panel headed by Dr Yasmin Othman of `Mas’ with a transcription factor associated the University of Malaya in Kuala Lumpur, with early flowering Malaysia, selected the best posters E. Santos, S. Remy, B. Coemans, E. Thiry, presented at the 1st international banana S. Windelinckx, R. Swennen and L. Sagi congress. We would like to thank Synergy Farms of Malaysia for graciously offering for Isolation of plantain promoters using the prizes to the winners listed below. firefly luciferase reporter gene Winners of Session 1 R. Sutherland, J.-V. Escalant, K. Kunert, N. van den Berg, A. Kiggundu and A. S. Subramaniam, M. Maziah, M.P. Abdullah Viljoen for Establishment of a banana and M. Sariah for Agro-bacterium-mediated transformation facility in South Africa for transformation of ‘Rastali’ engineering Fusarium wilt and banana H. Khanna, D. Becker, J. Kleidon and J. weevil resistance Dale for Agrobacterium-mediated trans- formation of Cavendish and `Lady finger’ J. Bartos, O. Alkhimova, M. Dolezelova, embryogenic cell suspensions E. De Langhe and J. Dolezel for Diversity in W.C. Wong, R.Y. Othman and K.N. Khalid genomic distribution of ribosomal DNA and for Biolistic-mediated transformation of cv. nuclear genome size in Musa

42 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 43 Winners of Session 2 constraints of production for farmers in R.A. Zorilla, T.O. Dizon, D.C. Pantastico, banana growing areas of Kenya J.I. Orajay, F.S. de la Cruz Jr., I. Van den Babita Jhurree-Dussoruth for Evaluation of Bergh and D. de Waele for Survey of `Petite naine’ in Mauritius nematodes in Quezon province, Philippines Nor Aini M. Fadzillah, Intan Nasrah Omar A. Belgrove, B. Nel and A. Viljoen for Shukri, Siti Khalijah Daud and Zakaria Characterization of fungal endophytes as Wahab for Aluminium toxicity induces lipid possible biological control agents against peroxidation and affects antioxidant enzyme Fusarium oxysporum f.sp. cubense activities in cultivars of Musa sp. M.A. Jimenez, J. Bermeo, M. Jama, Winners of Session 4 L.Perez and R. Maribona for Sensibility of Mycosphaerella fijiensis populations to Che Rahani Zakaria and Rahil Mohd for triazole and strobilurin fungicides in Ecuador Development of fruit rolls from banana Sam Zainun Che Ahamad for Quality of Winners of Session 3 frozen breaded banana M. Onyango, F. Nguthi, J. Mutisya K.P. Baiyeri for Moisture level of plant and F. Muniu for Characterization of residues used as storage media influenced banana cultivars, production practices and post harvest behaviour of mature plantains

An outbreak of banana xanthomonas wilt MusaNews (Xanthomonas campestris pv. musacearum) in the Democratic Republic of Congo In January 2004, following a request from 2003) but tended to be more severe. These FAO Goma, the first author accompanied include progressive yellowing, wilting and local agricultural officers on a visit to the blackening of leaves, as if scorched by fire. Masisi region, North Kivu province, in order Internally, yellow or brown vascular streaks to investigate a banana disease (Ndungo were seen throughout the plant and pockets and Kijana 2004). These initial observations of pale yellow bacterial ooze were especially suggested that the disease might be bacterial prominent in airspaces at the leaf base of the wilt caused by Xanthomonas campestris pv. pseudostem. Premature ripening and internal musacearum, which has recently been discoloration of fruits was observed, as was reported in Uganda (Tushemereirwe et al. blackening and shrivelling of the male bud. 2003). Subsequent visits were made in May The latter, however, was much less common and August 2004 and this report confirms the than what has been observed on the same earlier diagnosis. varieties in Uganda, where in newly affected Local farmers first observed the disease areas the first symptoms were often seen in 2001 at Bashali Mokoto village, 72 km on the flowers. Using methods described northwest of Goma in North Kivu (Figure 1). by Tushemereirwe et al. (2003), the The altitude at the site ranges between 1700 bacteria isolated at CABI Bioscience were and 1740 m. The varieties grown include indistinguishable from the X. campestris ‘Pisang awak’ (ABB) (90% of all bananas), pv. musacearum samples from Uganda. beer and cooking East African highland The isolates caused rapid wilting following bananas (AAA), the dessert bananas inoculation into young banana plants. ‘SukariNdizi’ (AAB) and Cavendish (AAA), As in Uganda, the disease was first and plantains (AAB) (Ndungo 2004). As in reported in 2001 but the situation in the Uganda, all banana genotypes are affected Democratic Republic of Congo is different. but ‘Pisang awak’ seems to be the first to get Contrary to the situation in Uganda, where infected and the Cavendish varieties last, the disease has spread at the average after the matooke and beer clones. alarming rate of 75 km per year, probably by The symptoms were similar to those insects visiting the male buds, the disease in observed in Uganda (Tushemereirwe et al. DRC has spread very slowly, from an initial

42 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 43 site of a few plants in one village (Bwere hill) and swampy areas. It may thus be prudent to to a radius of approximately 10 km. Towards destroy enset plants in the immediate vicinity the centre of this area the yield is almost of cultivated bananas and the presence of reduced to zero, which has an alarming the disease in enset should be investigated. impact on food security. Many bananas Apart from enset, no other alternative host continue to produce suckers but these are has been demonstrated so far. It is possible invariably infected from the motherplant and that the bacteria can infect other closely V. Ndungo works at the Faculté related species (such as Zingiberaceae, des sciences agronomiques rarely flower (Ndungo and Kijana 2004). The disease is also more intense close to five Marantaceae and Cannaceae) but so far de l’Université Catholique there is no evidence that this occurs in de Graben, Butembo, small lakes. The first and second authors have recently observed a new disease focus nature, and even if it does, it may not be Nord-Kivu, DRCongo, important for the spread of the disease. [email protected], about 20 km from the first one, so continued K. Bakelana at INERA Mvuazi vigilance and control actions are necessary. References Research Centre, P.O.Box Infected flowers are much less common Ndungo V. 2004. La situation de la culture du bananier 2039, Kinshasa, Gombe, and it appears that the principal mode of et du bananier plantain en République Démocratique spread may differ from the one in Uganda. du Congo, Communication présentée à la septième RDCongo, [email protected] réunion du comité de pilotage de MUSACO, Limbé, S. Eden-Green at EG In DRC, control will be more a matter of Cameroun, 7-11 June 2004. Consulting. 470 Lunsford Lane, trying to eradicate the disease and cleaning Ndungo V. & R. Kijana. 2004. Diagnostic et stratégies up infected fields rather than removing male pour la lutte durable contre la maladie des bananiers Larkfield, Kent ME20 6JA, UK et bananiers plantain dans la collectivité des Bashali, [email protected] and buds to prevent insect transmission. Territoire de Masisi, Province du Nord–Kivu, DRC, G. Blomme at INIBAP It is impossible to ascertain the origin of Goma, 26–29 January 2004. 21pp. Regional Office, P.O.Box the outbreak. One hypothesis is that the Tushemereirwe, W., A. Kangire, J. Smith, F. Ssekiwoko, M. Nakyanzi, D. Kataama, C. Musiitwa & R. Karyaija. 24384, Kampala, Uganda disease has recently spread from wild enset 2003. An outbreak of bacterial wilt on banana in [email protected] plants, which are found on nearby hillsides Uganda. InfoMusa 12(2):6-8.

Musa News Bacterial wilt (Xanthomonas campestris pv. musacearum) on enset and banana in Ethiopia

Enset (Ensete ventricosum) is a staple food Development, Co-operation and Technical for over 12 million people in the southern Assistance (VVOB), has recently been highland areas of Ethiopia. It grows best conducted in the main enset and banana at altitudes ranging from 2000 to 2700 m growing regions. The largest banana (Brandt et al. 1997). Enset bacterial wilt producing area is located at Arba Minch in was first reported in Ethiopia by Yirgou and southern Ethiopia (1200 m) (Figure 1). This Bradbury (1968) and is currently found in all area is geographically separated from the the enset growing regions and on wild enset wetter highland areas where enset is grown. plants, although it has not been reported on No banana bacterial wilt has been reported enset in other countries. It is mainly spread so far in this area. through infected farm tools, infected planting The second banana growing area is material, repeated transplanting that damage located in western Ethiopia and most of the corm and roots, animals fed infected the bananas are found between 1050 and plants and possibly insects feeding on the 1700 m (Figure 1). Distances of over 100 foliage. Since cultivated enset is harvested meters between plots are very common. for its starchy pseudostem and corm, it is not Although it is not the main crop, enset is normally allowed to flower. As a result, the also grown in this area and enset bacterial question of insects infecting flowers does wilt is present. Most farmers indicated that not normally arise, but symptoms typical of the disease (locally called cholera) has been insect transmission have been observed on present on enset and banana for some 20 banana flowers (Yirgou and Bradbury 1974). years. The varieties grown in this region are An enset and banana pest and disease ‘Kenya’ (‘Dwarf Cavendish’), ‘Faranji muz’ survey, funded by the Flemish Association for (‘Pisang awak’), ‘Abesha muz’ (a matooke

44 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 45 clone) and ‘Red abesha’ (‘Uganda red’), all Figure 1. Main enset and banana growing sweet bananas. Bacterial wilt seems more regions in Ethiopia (adapted from Brandt et al. common on banana than on enset. The 1997).

farmers indicated that banana bacterial wilt Addis Ababa mainly attacks ‘Pisang awak’ and in some cases ‘Red abesha’. Male bud infection was observed on a ETHIOPIA large number of ‘Pisang awak’ mats in the SUDAN areas below 1700 m. A few farmers reported infection in their matooke clones. ‘Dwarf Cavendish’, which is very widely grown in KENYA this region, apparently does not get infected. Enset growing areas It is believed that the absence of male bud Banana growing areas infection is linked to the persistent male bracts, which could constitute a barrier to active banana bacterial wilt eradication insect transmission. This observation is programme is currently operational. Early in agreement with a report from Bakelana removal of the male bud is not practiced. and Ndungo (2004), who stated that the Given that the cultivation of bananas is a Cavendish varieties present in eastern growing activity, focus should be put on Democratic Republic of Congo (DRC) were controlling the disease and preventing the last genotypes to get infected. its spread through timely debudding, the Scattered banana mats are also found removal of infected plants, the use of clean in the south-central enset growing region, farm tools and clean planting materials. in areas over 1700 m. Male bud infection has not yet been observed in this region, References possibly because the higher altitude and Bakelana K. & V. Ndungo. 2004. La maladie de Bwere: une lower temperatures are not favourable to bactériose dévastatrice de la culture de la banane dans la province du Nord-Kivu en République Démocratique insect vectors. This is in agreement with du Congo. Rapport de mission FAO. 11pp. observations made at over 1700 m in North Brandt S.A., A. Spring, C. Hiebsch, J.T. McCabe, Kivu, DRC, where male bud infection is very E. Tabogie, G. Wolde-Michael, G. Yntiso, M. Shigeta & S. Tesfaye. 1997. The «Tree Against Hunger»: uncommon. In contrast, male bud infection Enset-based Agricultural Systems in Ethiopia. has been postulated to be one of the American Association for the Advancement of Science, Temesgen Addis and Fikre primary causes of new infections in Uganda Washington, DC, USA, 56pp. Yirgou D. & J.F. Bradbury. 1968. Bacterial wilt of Enset Handoro work at the Southern (<1600 m), and is widespread in south- (Ensete ventricosum) incited by Xanthomonas Agricultural Research Institute western Ethiopia (<1700 m). musacearum sp. Phytopathology 58:111-112. (SARI), in Awassa, Ethiopia, Numerous extension activities have been Yirgou D. & J.F. Bradbury. 1974. A note on wilt of banana and Guy Blomme at the caused by the Enset wilt organism Xanthomonas conducted or are ongoing in Ethiopia to musacearum. East African Agricultural and Forestry INIBAP Regional Office in control enset bacterial wilt. However, no Journal 40(1):111-114. Kampala, Uganda.

Recommended names of banana diseases and their MusaNews pathogens

Three plant pathologists with experience fungi and viruses), which includes selected with banana diseases, David Jones, Chris important literature references. These two Hayward and John Thomas, have worked lists have been placed on the ISPP-CCN with the International Society for Plant website at http://www.isppweb.org/names/ Pathology’s Committee for Common Names common.asp. of Plant Diseases (ISPP-CCN) to prepare a Choosing the “best” name for a disease list of recommended names of diseases of can be difficult. A disease may have bananas. This list is accompanied by a second multiple names, depending on the country, list of pathogen names (mainly bacteria, locality or user. Internationally, as many

44 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 45 as seven or eight names may be used for Another example is the wilt disease caused the same disease. Nobody is happy to find by Fusarium oxysporum f. sp. cubense. The that a name they have long used is not recommended name is “Fusarium wilt”, the name recommended for international consistent with the name widely used for standardization. It has not been easy to similar wilt diseases of both banana and reach a consensus on some names, even many other hosts. The alternative name, within the ISPP-CCN. “Panama”, is included in the disease list as In choosing the recommended names, a non-preferred name. the ISPP-CCN has kept in mind certain A third example is the bacterial wilt disease principles (guidelines) with which the best caused by Ralstonia solanacearum race 2. names of diseases should be consistent. In The recommended name is “Moko bacterial particular, a name should include a suitable wilt”, combining the commonly used name descriptor, indicating a major disease “Moko” (the name of a particularly susceptible symptom. A meaningless name, even if it is banana clone) with the descriptive name “bacterial wilt” often used for wilt disease short and memorable, is relatively unhelpful caused by R. solanacearum in both banana to people not familiar with a disease. and other hosts. In recommending names, the ISPP-CCN Names for diseases in the list has tried to be consistent with certain recommended by the ISPP-CCN can be working rules. For instance, disease names challenged by anyone preferring a different should be in English, because of its wide name. You are invited to communicate your use in international communications. Also, suggestions to the Chair of the ISPP-CCN, only well-studied diseases of importance David Teakle, [email protected] are included in an effort to avoid future name It is expected that, following consideration changes. of challenges, names approved by the ISPP- One important banana disease for which CCN will be commonly used as “standard” choosing the name has proved difficult is the names in international publications, inter- leaf spot disease caused by Mycosphaerella national meetings, etc. In conversation, fijiensis. This is called “Black Sigatoka (leaf personal communications and locally spot)” in many countries, but “Black leaf some approved names will no doubt be streak” in some others. As a compromise, abbreviated for convenience, or alternative both names are accepted as valid “traditional” names in English or other alternatives. languages will be used.

Forum Planting depth participatory on-farm research), appropriate extension and information communication, In the early 1980s, I had the privilege of as well as experience sharing. spending a few days with the late George The paper by Bakhiet and Elbadri can be Wilson (Vol. 13 No. 1) during his visit to an entry point for a discussion on banana Gabon. We discussed planting depth, which planting depth after some clarifications are is also the topic of an article by S.B. Bakhiet provided. For example, which cultivar was and G.A.A. Elbadri in the same INFOMUSA used in the trial? Was the crop irrigated and, issue. We concluded that there was no need if so, how was water provided? Was the trial to plant banana deep given its inherent shallow root system, which is largely about depth of planting or size of the hole, or concentrated on the top soil layer, with some both? If the focus was on depth of planting, of the roots growing in the mulch (where was the size of the hole similar for the there is mulching). different planting depths? Which criterium Nevertheless, from my largely African was used for measuring depth of planting? experience, the issue of planting depth with Was it the bottom point of the sucker? What regards to bananas (and other perennial was the size of the sword suckers and how crops) remains an unresolved subject that homogeneous was the size of the suckers deserves further investigation (such as used in the trial?

46 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 47 Planting depth may be a different issue in involved in commercialisation, competition a commercial plantation or under smallholder has increased, our organic bananas are condition, e.g. whether mechanization is increasingly eaten in a greater number of involved or not. Other factors that may also countries, quality is steadily improving and have an influence include the genomic group the perspective of growth of organic banana (e.g. AAA, AAB or ABB), the presence of increasingly lends itself to the involvement of pests and diseases, mixed or sole cropping efficient private firms which produce, locally, and land husbandry. Planting depth is an inputs for the banana industry. important issue because of its impact on In 2004, the volume of bananas exported agronomic performance and sustainability, from Peru increased by 34% and their value and on labour and economic issues, and increased by 39% in comparison with the merits further discussion. previous year, as a result of the higher Guy Evers, Senior Agricultural Officer selling prices. In 2004, 10 organic banana FAO Investment Centre Division export companies settled in northern Peru, Southern and Eastern Africa Service (TCIS) compared to two firms in 2000. E-mail: [email protected] To date, the transnational Dole captured 59% of the export value, whereas Bioorgánika Exports from an organic and Gronsa captured 22%. The remaining value of exports was captured by Banano banana paradise del Norte, Bio Costa, Inka Banana, Organia, In these days far from my country, six years Grupo Orgánico Nacional, AgroPiura, after the start of the organic banana project Biofruit, Productos Orgánicos de Piura, in the Chira valley, supported by the Peruvian Tumpibanana and the recently created Ministry of Agriculture and the watchful Agrorganic. collaboration of INIBAP, export of organically The firms Biofruit and Tumpibanana produced banana from Peru is beginning to sent 100% of their export to neighbouring take its place as the star of export production, Ecuador, which then re-exported organic having been the most dynamic fruit export bananas to countries such as the USA. The sector over the past years. In addition to the transnational Dole was responsible for 83% benefits organic bananas have generated in of the volume exported to the USA and 52% Peru, as published in INFOMUSA June 2004, of exports to Belgium, at an average price of we can expect they will continue to produce US$6.4 per box. Seventy five per cent of the strategic benefits such as the generation of volume exported to The Netherlands was by new sources of work and improved income the firm Bioorgánica, at an average price of for small-scale growers in northern Peru. US$8.1 per box. The firms Inka Banana and The objective of the project, described as Organia exported 51% and 34% respectively “An organic banana paradise” in the INIBAP of the total volume to Japan. 2003 annual report, was to improve the The German and British markets were revenues of small-scale banana producers recently penetrated and for the first time affected by El Niño by exporting bananas. there was participation in the Chinese Despite the predictions of well-known export market. Last year, Japan, Belgium and firms saying that the banana production areas The Netherlands markedly increased their in Peru were too remote from the markets in imports, while the rate of export to the United the North, this project started exports in States decreased over the past four years 2000 in the context of organic agriculture as and the growth rate may be negative by the an alternative for the thousands of producers end of 2004 . This situation could be caused who were receiving ever lower prices for their mainly by competition from countries that banana production while paying increasingly are closer such as the Dominican Republic, higher prices for inputs. Mexico and Ecuador. Looking at today’s export figures, we From the start of the project to the present, can say that we have met the challenge organic banana from Peru has penetrated 10 to develop our comparative advantages, countries, the USA (61%), Belgium (16%), which we had set for ourselves in 1998. The The Netherlands (12%), Germany (5%), export of banana is not only a reality, but it Japan (4%), France, UK, Ecuador, Spain keeps on increasing. More private firms are and China.

46 InfoMusa - Vol. 13 - No.2 InfoMusa - Vol. 13 - No.2 47 The average rate of change in FOB* prices regarding the protection of the environment grew at a rate of 10% between 2001 and and the importance of producing safe and 2004, from US$5.6 per 18 kg box in 2001 nutritious food. Moreover, the participation to US$7.4 in 2004. The increased banana of more private firms, supported by regional prices were mainly due to the opening of new research organizations and certification markets, such as Japan, and the growth of agencies, will generate, in the medium term, sales to markets with better prices, such as the development of a production chain that The Netherlands and Belgium, not forgetting will result in the generation of complementary that the FOB prices of exports to the USA activities for improved production and also increased progressively. provision of services. The totality of production is achieved by The development of applied research, small-scale producers who sell their production the creation of private firms involved in to export firms who then certify the production, the production of inputs for export and, of processing and commercialization of the course, a marketing strategy positioning organic bananas, and at the same time Peru as “A Paradise of Organic Bananas”, provide technical assistance to producers. are the main themes that need to be The growth in value of the exports increases addressed to develop the production chain the awareness of small-scale producers of organic bananas in Peru. Salomón Soldevilla Canales * FOB: free on board. E-mail: [email protected]

In memory of Dr Maribona On 31 October 2004, the banana and banana-black leaf streak disease model biotechnology community lost one of its most because of the importance of the disease active collaborators, Dr Rodolfo Heriberto in Ecuador. In 1999, he headed the Musa Maribona Hernández, the director of CIBE biotechnology project for sustainable (Centro de investigaciones biotecnologicas agriculture, which led to the creation of CIBE. del Ecuador) at ESPOL (Escuela Superior In addition to being a research centre, CIBE Politecnica del Litoral) in Guayaquil, provided extension to farmers via lectures and Ecuador. field demonstrations as part of its BANARED Born in Cuba in 1939, he showed an early unit. Its collaboration with organic banana interest in science. He studied medicine and farmers has also become the foundation of biology at Harvard University in the US and ground-breaking work on the molecular and obtained a PhD from Lomonosov university in Moscow in 1979. After his return to Cuba, he biochemical mechanisms underpinning the dedicated himself to the genetic improvement plant’s defenses. of sugar cane through somaclonal variation. Those who knew and worked with Dr He arrived in Ecuador as a consultant to Maribona will remember him for his unflagging ESPOL in 1997 and in 1998 became the support to young people who embarked scientific director of SEBIOCA (Sociedad in a career in science, his vast scientific Ecuatoriana de Biotecnología). He initiated knowledge and his pleasant personality. collaboration projects with Flemish univer- Isabel Jimenez, CIBE, Ecuador sities in Belgium, concentrating on the Rony Swennen, KULeuven, Belgium

Erratum In the article “Evaluation of new banana hybrids against black leaf streak disease”, published in the previous issue of INFOMUSA, we wrote that the disease against which the hybrids had been evaluated was black leaf streak disease, caused by Mycosphaerella fijiensis. In fact, it was Sigatoka disease, caused by Mycosphaerella musicola. We regret the error.

48 InfoMusa - Vol. 13 - No.2 Instructions to authors

NFOMUSA is an international journal published twice Discussion: The discussion should not contain extensive a year in English, French and Spanish. Our focus is to repetition of the results section nor should it reiterate the I provide an outlet for research results and reports of interest introduction. It can be combined with the results section. to the Musa community. As INFOMUSA publishes articles on References: All references to the literature made in the any Musa-related issue, authors should aim for simple and text should be referred to by author(s) and year of publication clear phrases that avoid unnecessary jargon in order to make (e.g.: Sarah et al. 1992, Rowe 1995). References to not their paper accessible to readers in other disciplines. widely circulated documents, such as annual reports, and Manuscripts should be prepared in English, French or citations of personal communications and of unpublished Spanish and should not exceed 2500 words, including data should be avoided. A list of references, in alphabetical references. They should be double-spaced throughout. All order, should be provided at the end of the text. pages (including tables figures, legends and references) Please follow the style shown below: should be numbered consecutively. Periodicals: Sarah J.L., C. Blavignac & M. Boisseau. 1992. Include the full name of all the authors of the paper, Une méthode de laboratoire pour le criblage variétal des together with the addresses of the authors at the time of bananiers vis-à-vis de la résistance aux nématodes. Fruits the work reported in the paper. Indicate also the author 47(5):559-564. nominated to receive correspondence regarding the paper. Books: Stover R.H. & N.W. Simmonds. 1987. Bananas (3rd Manuscripts can be sent as e-mail attachments or put on edition). Longman, London, United Kingdom. a 3.5-inch disk for PC-compatible machines. Please indicate Articles (or chapters) in books: Bakry F. & J.P. Horry. the name and version of the word processing software used 1994. Musa breeding at CIRAD-FLHOR. Pp. 169-175 in and the author’s e-mail address. In either case, we will need The Improvement and Testing of Musa: a Global Partnership to receive by mail two printed copies of the manuscript. (D.R. Jones, ed.). INIBAP, Montpellier, France. Title: The title should be as short as possible and should Illustrations and tables: These should be numbered not have numbers, acronyms, abbreviations or punctuation. consecutively and referred to by these numbers in the text. Abstract: An abstract, not exceeding 200-250 words, Each illustration and table should include a clear and simple should be provided. It should concisely summarise the basic caption. Figures and tables should be inserted after the contents and should be sent in the same language as the references or in separate files. manuscript. Translations (including the title) into the two Graphs: provide the corresponding raw data with the graphs, if possible in Excel format. other languages should also be sent if this is possible. Drawings: provide originals if this is possible. Key words: Provide a maximum of six key words, in Photographs: We prefer hard-copy printouts of alphabetical order, below the native-language abstract. photographs (bright paper with good contrast for black and Introduction: The introduction should provide the rationale white photographs; good quality proofs and films or original for the research and any relevant background information. slides for colour photographs), but please remember that Since it is not meant to be an exhaustive review of the topic, we will not return them. We will publish pictures that have the number of references should be kept to a minimum. been scanned or taken with a digital camera as long as the Introductions on the importance of bananas as a staple food resolution is high enough (1 million pixels or a minimum of or a traded commodity should be avoided, unless they are 300 dpi when the photograph is in real size). Acceptable absolutely necessary for the comprehension of the article. file types are JPEG, TIFF and EPS. Avoid sending photos Materials and methods: The authors should provide inserted in a Word or Power Point document, unless they are enough details of their experimental design to allow the reader accompanied by a better quality alternative. to gauge the validity of the research. For commonly used Acronyms: These should be written in full the first time they materials and methods, a simple reference is sufficient. appear in the text, followed by the acronym in parenthesis. Results: The unit should be separated from the number Cultivar names: The name of the cultivar should be placed by a single space and follow SI nomenclature, or the between single quotation marks. If the name is a compound nomenclature common to a particular field. Unusual units or noun, only the first word starts with a capital letter, unless the abbreviations should be defined. other refers to a place or person. Use the most commonly Present data in the text, or as a figure, or a table, but agreed upon name, such as ‘Grande naine’ and avoid local never in more than one of these ways. Avoid extensive variations or translations, such as ‘Gran Enano’. use of graphs to present data that could be more concisely Note: When plant material used for the experiments presented in the text or in a table. Limit photographs to those reported originates or is registered in the INIBAP genebank, that are absolutely necessary to show the experimental its accession number (ITC code) should be indicated within findings. the text or in a tabular form.

Thank you in advance for following these instructions. This will facilitate and accelerate the editing work.

48 InfoMusa - Vol. 13 - No.2 INIBAP Publications Latest publication INIBAP 2004. INIBAP Annual Report 2003. International network for the Improvement of Banana and Plantain, Montpellier, France. Recent publications S. Mohan Jain and R. Swennen (eds). 2004. Banana improvement, cellular, molecular biology, and induced mutations. This 392-page book, co-published by FAO/IAEA and INIBAP, presents the results from the FAO/IAEA Coordinated Research Project entitled “Cellular biology and biotechnology including mutation techniques for creation of new useful banana genotypes”. The book also contains several review papers providing up-to-date information on biotechnological tools that can be used to produce new Musa varieties with desirable characters in a more rapid and efficient way. Coming soon D.W. Turner and F.E. Rosales (eds). 2005. Banana root system: towards a better understanding for its productive management. Proceedings of an International Symposium.

To obtain a complete list of our publications, consult our website or contact Leila Er-rachiq at INIBAP headquarters in Montpellier. E-mail : [email protected]

INIBAP addresses

• Headquarters: Associate Scientist, Musa technology transfer: Parc Scientifique Agropolis II Dr Inge Van Den Bergh 34397 Montpellier Cedex 5 - FRANCE c/o IRRI, Rm 31, GS Khush Hall e-mail: [email protected] Los Baños, Laguna 4031 Fax : (33) 467 61 03 34 Philippines Director: Dr Richard Markham Fax: (63-49) 536 05 32 e-mail: [email protected] e-mail: [email protected] Coordinador, Musa Genetic Improvement: Dr Jean-Vincent Escalant • Regional Office for West and Central Africa e-mail: [email protected] Regional Coordinator: Dr Ekow Akyeampong Coordinator, Musa Genomics and Genetic Resources Regional information officer for Africa: Conservation: Dr Nicolas Roux Mr Josué Tetang Tchinda e-mail: [email protected] Associate Scientist, Musa technology transfer: Coordinador, Musa Agroecosystems and Channels for Added Ms Kim Jacobsen Value: Dr Charles Staver c/o CARBAP - BP 12438 e-mail: [email protected] Douala, Cameroon Coordinator, Information/Communications: Tel./Fax: (237) 342 91 56 Ms Claudine Picq E-mail: [email protected] e-mail: [email protected] Officer in charge MGIS: Ms Elizabeth Arnaud • Regional Office for Eastern and Southern e-mail: [email protected] Africa Accountant: Mr Emmanuel Gonnord Regional Coordinator: Dr Eldad Karamura e-mail: [email protected] Associate Scientist: Musa technology transfer: Impact assessment specialist: Ms Charlotte Lusty Dr Guy Blomme e-mail: [email protected] PO Box 24384 Kampala, Uganda • Regional Office for Latin America and the Fax: (256-41) 28 69 49 Caribbean e-mail: [email protected] Regional Coordinator: Dr Franklin E. Rosales Associate Scientist, Musa technology transfer: Dr Luis • INIBAP Transit Center (ITC) Pocasangre Officer in charge: Ms Ines Van Den Houwe c/o CATIE Katholieke Universiteit Leuven Apdo 60-7170 Turrialba, Costa Rica Laboratory of Tropical Crop Improvement Tel./Fax: (506) 556 2431 Kasteelpark Arenberg 13, e-mail: [email protected] B-3001 Leuven Belgium • Regional Office for Asia and the Pacific Fax: (32-16) 32 19 93

www.inibap.org Regional Coordinator: Dr Agustín Molina e-mail: [email protected]