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Mycosphaerella musicola, M. fijiensis and M. eumusae are known to cause banana yellow Sigatoka, black Sigatoka and Eumusae leaf spot diseases respectively. However, differentiating the causative species has been challenging and the responses of banana landraces to this pathogen were little known. Purposive sampling surveys were conducted in different agro-climatic zones of Kerala state, India, to collect the leaf samples with Sigatoka leaf spot-like symptoms, to document the symptom expression on different landraces and to confirm the identity of the pathogen at species level. Fields surveyed during the post-monsoon period had 100% disease incidence with highest per cent disease severity of 43.90% in nine-month old cv. Palayankodan, while lowest PDS of 3.33% was observed in three-month old cv. Njalipoovan, during a pre-monsoon survey. Initial symptoms were small brown streaks, later developing into oval or elliptical brown spots with greyish centre and subsequently coalescing for leaf necrosis. Symptoms in different landraces varied across the zones. Sequencing and analysis of the ITS region from 50 isolates collected during the survey showed 99–100% homology with M. eumusae. Phylogenetic analyses further proved the species identity of the local isolates. Comparing the ITS barcodes of the three species of Mycosphaerella along with the local isolates confirmed that the pathogen inciting Sigatoka leaf spot in Kerala state, India, is Mycosphaerella eumusae.

Para o cultivo de banana utilizam-se alguns agentes químicos para combater determinadas pragas, uma destas é a Sigatoka, causada pelo fungo Mycosphaerella Musicola. Ela ataca as folhas das bananeiras, diminuindo drasticamente a produtividade da fruta. Para eliminação desta praga, realiza-se pulverizações de agentes químicos, a quantidade destas variam de acordo com diversos fatores. Para realizar a pulverização utiliza-se o atomizador de ar, tipo canhão bananeiro, objeto de estudo deste trabalho. Este atomizador possui uma turbina radial, que impulsiona ar para um direcionador giratório de 4 a 6m de altura, para fazer o lançamento dos agentes químicos necessários no bananal. Existem diferentes combinações disponíveis de turbinas e ventiladores para este equipamento e o objetivo deste trabalho é avaliar através de análises computacionais combinatórias, as diferentes combinações indicando o melhor conjunto, para aprimorar a trajetória e temperatura de saída do fluído melhorando a eficiência da pulverização, aumentando a produtividade com menor número de pulverizações e consequentemente reduzindo o impacto ao meio ambiente. O trabalho foi desenvolvido através de uma pesquisa exploratória em campo, também conhecida como “pesquisa de base”. Nos resultados pode-se observar que dentre as condições analisadas de trajetória, temperatura e pressão, que o melhor conjunto de turbina e ventilador, que oferece os melhores resultados é a turbina com saída de ar central e ventilador de pás retas, com diferença de temperatura de 1,7°C menor, para as temperaturas coletadas em campo e 0,36°C menor, para as temperaturas das análises computacionais.

Three Gros Michel mutants (‘IBP 5-B’, ‘IBP 5–61’ and ‘IBP 12’) from the Cuban Instituto de Biotecnologia de las Plantas, two semi-dwarf Gros Michel varieties (‘Highgate’ and ‘Cocos’) and a Thai accession (‘Hom Thong Mokho’) were evaluated in Australia over a five year period. They were screened for their resistance to Fusarium wilt Race 1 (FocR1) caused by the pathogen Fusarium oxysporum f.sp. cubense, as well as resistance to yellow Sigatoka (Pseudocercospora musae Zimm [teleomorph Mycosphaerella musicola Leach]). They were also grown for a plant and ratoon crop in the tropics (17°S) and a plant crop in the subtropics (28°S) with no disease pressure to record their agronomic characteristics. They were compared with Australian industry standards, ‘Williams’ (AAA, Cavendish subgroup) and ‘Lady Finger’ (AAB, Pome subgroup). In the subtropics the Gros Michel mutants and semi-dwarf accessions were sensitive to cold and very susceptible to FocR1 and yellow Sigatoka while their agronomic performance in the tropics was good, with ‘Highgate’ having the best bunch weight on a shorter, more manageable plant. Of the six accessions evaluated, ‘Hom Thong Mokho’ showed the highest level of resistance to FocR1 although it had poor cold tolerance, as did the other Gros Michel selections, and consequently had low productivity compared to ‘Williams’ and even ‘Lady Finger’. However in the warmer, more humid tropics ‘Hom Thong Mokho's performance was much better and it was less susceptible to yellow Sigatoka than the other Gros Michel selections. Subsequent genetic analysis by Christelova et al. (2011) has revealed that although ‘Hom Thong Mokho’ is marketed as a Gros Michel variety in Asia, it is closer to the Rio subgroup (AAA) of dessert bananas.

Silicon (Si) is known to reduce the severity of pathogens on many plants. This study aimed to determine the effect of silicon (Si) in reducing the severity of yellow Sigatoka (Mycosphaerella musicola) on banana plants cultivated in nutrient solution. The treatments included five concentrations of silicic acid (H4SiO4): 0, 0.5, 1.0, 1.8 and 3.6 mmol L−1. The area under the disease severity progress curve (AUDSPC) was calculated for each treatment, and the nutrient content of the leaves determined. AUDSPC for plants receiving 3.05 mmol L−1 H4SiO4 was 49.27% lower compared to plants receiving no supplemental H4SiO4. In contrast, plants grown in a solution of 3.6 mmol L−1 H4SiO4 had 23.53% more Si content in the leaves compared to plants cultivated without supplemental H4SiO4. These results suggest Si could be used as a component in the integrated management of yellow Sigatoka.

The genetic structure of Mycosphaerella musicola has never been investigated in Brazil to address epidemiologically related questions associated with yellow sigatoka. A total of 223 single-conidium isolates from four regions (North, South, Zona da Mata and Triângulo Mineiro) of Minas Gerais State, Brazil, were used to assess the population genetic structure of M. musicola. Isolates were characterized regarding the frequency of the MAT1-1-1 or MAT1-2-1 idiomorphs and polymorphism at nine microsatellite loci. The mating-type ratio in three of the four subpopulations was c. 1:1. A total of 87 alleles and 216 multilocus genotypes were identified. The overall population was in linkage equilibrium. Most (93.9%) genetic variation was detected within the subpopulations and there was weak differentiation between them. In total, eight genetic groups were detected and isolates of seven groups were present in all regions. The population of M. musicola in Minas Gerais seems to have high evolutionary potential: it is panmictic and both sexual reproduction and gene flow affect genetic variability. Strategies to avoid fungicide resistance should be enforced and breeding programmes need to consider quantitative resistance in the banana cultivars.

Two to three sprays of pyraclostrobin 13.3% + epoxyconazole 5%(Opera 18.3%)@0.15% effectively controlled the Sigatoka leaf spot disease but this treatment was as par with propiconazole 0.1 per cent. The next best treatments were pyraclostrobin 13.3% + epoxyconazole 5% (Opera 18.3%)@0.125% and epoxyconazole 7.5%EC.With regard to yield, the treatment propiconazole @ 0.1 % recorded the highest yield of 31.94 t/ha followed by pyraclostrobin 13.3% + epoxyconazole 5%@0.15% (29.95 t/ha) and it was lowest in control. Phytotoxicity symptoms like chlorosis, necrosis, wilting, scorching, hyponasty and epinasty were not noticed in any of the treatments.

A thorough assessment of the distribution of Mycosphaerella spp. associated with banana in Minas Gerais State, Brazil, was conducted after Mycosphaerella fijiensis was first reported to occur in this region in 2005. From 2009 to 2011, 80 fields located in 20 municipalities including the same fields where the disease was first reported were sampled. A total of 800 samples of leaf tissue with symptoms similar to those of yellow or black Sigatoka diseases were examined, and 239 isolates were obtained. The identification of the fungi was based on morphological characters combined with DNA sequences obtained after amplification with species-specific primers and phylogeny inferred from the internal transcribed spacer region of Mycosphaerella strains from banana. All 239 isolates were identified as Mycosphaerella musicola. The absence of M. fijiensis in the samples may have been due to misidentification of M. fijiensis or the displacement of M. fijiensis by M. musicola. It is now apparent that yellow Sigatoka caused by M. musicola is the prevailing leaf spot disease of bananas in Minas Gerais State and that regulatory/legislative control measures need to be revised based on our findings.

The efficacy of chlorothalonil and paraffinic oil alone and in combinations with the registered fungicides propiconazole, tebuconazole, difenoconazole, epoxiconazole and pyrimethanil was evaluated in a field experiment over two cropping cycles in 2013 and 2014 in Northern Queensland, Australia, for control of yellow Sigatoka (caused by Mycosphaerella musicola) of banana. The predominantly applied by the banana industry treatment mancozeb with paraffinic oil was included for comparison. The results from the two cropping cycles suggested that all chemicals used with paraffinic oil were as effective or more effective than when applied with chlorothalonil, and chlorothalonil alone. Difenoconazole and epoxiconazole with paraffinic oil followed by propiconazole with paraffinic oil were the most effective treatments. Pyrimethanil and tebuconazole plus chlorothalonil were the least effective treatments. None of the chemical treatments was phytotoxic or reduced yield.

An endophytic bacterium isolated from banana G-9 (AAA genotype) leaves exhibited strong antagonistic activity against Mycosphaerella musicola. The isolate was identified as Pantoea ananatis 4G-9 by 16S rRNA sequence analysis. Secondary metabolite obtained from P. ananatis 4G-9 was found to have antifungal activity. The active compound was purified from crude extract using column chromatography. Purity of the active compound was assessed using high-performance liquid chromatography. Spectral analysis of compound using infrared, mass spectrometry and nuclear magnetic resonance indicated that the compound structure is an indole derivative. The compound showed strong and dose-dependent antifungal activity against M. musicola. This is the first report on P. ananatis isolated as an endophyte from banana leaves and its antifungal activity against M. musicola.

El estudio se realizó en la Finca Integral Jatum Paccha, ubicada a 2 Km de la Parroquia 10 de Agosto vía a la Parroquia El Triunfo y, en la Finca Integral Unión Base, localizada a 3 Km de la cuidad de Puyo, durante el 2017. Constituyendo el objeto de la investigación las principales plagas de Plátano, para dar respuesta al problema se propuso los siguientes objetivos: determinar las principales plagas del cultivo de Plátano, su importancia y la estrategia de Manejo fitosanitario del cultivo óptimo para resolver el problema de los daños de las plagas, utilizando la metodología del Dr. Iparraguirre et al. (1998), CIBA - GEIGI (2000) y León et al (2007). Se determinó que las Plagas más importantes fueron Mycosphaerella musicola (Leach ex Mulder.), Mycosphaerella fijiensis (Morelet),y el Mosaico del pepino (CMV); como Sistemas de Control Fertilización + Deshoje y Fertilización + Deshoje + Fungicida orgánico Timorex Gold, los más efectivos respectivamente al bajar por debajo del Umbral Económico (grado 2) el desarrollo de la enfermedad, grado medio de afectación y disminuir su distribución en el área de estudio; así como, obtener los mejores índices cualitativos de cosecha del cultivo del plátano, destacándose con respecto a la floración el Sistema Fertilización + Deshoje.

The Machine Learning techniques in precision agriculture offer new prospects for the monitoring and identification of phenotypic characteristics in crops,such as physiological, biotic and abiotic features, as a manifestation of diseases and pests, hydric and nutritional stress. The algorithms used in the processes seek the recognition of standards from Remote Sensing data, such as aerial imagesobtained through Unmanned Aerial Vehicles -UAVs. This scenario includes banana farming, an activity of great economic importance, being one of the most consumed fruits in the world, with big nutritional value. The banana cropis affected by severaldiseases and among them, yellow sigatoka, which is one of the main limiting factors to its cultivation, causing considerable losses in fruit production. In this context, searching for the basic assumptions for identification, classification, quantificationand prediction (ICQP) of phenotypic factors, the general objective of this work was to use remote sensing techniques, machine learning and high spatial resolution aerial images to monitor the severity of the yellow sigatoka attack in banana culture. Monthly flights were carried out in banana plantations in the city of Russas, Ceará, Brazil, belonging to the company Frutacor, using UAVInspire 1, shipped with X5 (panchromatic RGB) camera of 16 megapixels and 8 bytes. The algorithms Maximum Likelihood, Mahalanobis Distance and Minimum Distance, were considered as easy interface and fast processing, using the PhotoScan software. The algorithms were evaluated by the Kappa statistic and the Global Accuracy Index and the data obtained by the tests, compared to the field surveys. As a result, the Minimum Distance algorithm achieved better performance (99.28% accuracy) for the month of September 2017, and 2.44% of the degree of severity of the yellow sigatoka, compared to the field survey, which resulted in a degreeof infection from 1% to 5%. For the months of October and November, the Maximum Likelihood algorithm obtained 89.77% and 78.76% of accuracy, approaching the values collected in the field, demonstrating that the tools for monitoringleaf spots can be performed by means of techniques remote sensing, computational learning, and high spatial resolution panchromatic images. As técnicas de Machine Learning aplicadas à agricultura de precisão oferecem novas prospecções para o monitoramento e a identificação de características e identificação de padrões. Neste cenário, insere-se a bananicultura, atividade de grande importância econômica, sendo uma das frutas mais consumidas em todo o mundo, com grande valor nutricional. A cultura é afetada por diversas doenças e, dentre elas, a sigatoka-amarela, que é um dos principais fatores limitantes ao seu cultivo, provocando consideráveis prejuízos na produção de frutos. Neste âmbito, buscando os pressupostos básicos de identificação, classificação, quantificação e predição de fatores fenotípicos, o objetivo geral deste trabalho foi utilizar técnicas de sensoriamento remoto, aprendizagem computacional e imagens aéreas de alta resolução espacial para realizar o monitoramento da severidade do ataque da sigatoka-amarela na cultura da banana. Foram realizados voos mensais em plantio comercial de bananeiras pertencente à empresa Frutacor, na cidade de Russas, Ceará, Brasil, utilizando VANT Inspire 1, embarcado com câmera X5 (pancromática RGB) de 16 megapixels e8 bytes. Os processamentos foram realizados através do software PhotoScan e, para as classificações, foram utilizados os algoritmos Maximum Likelihood, Mahalanobis Distance e Minimum Distance, considerados de fácil interface e rápido processamento. Os algoritmos foram avaliados pela estatística de Kappa e Índice de Exatidão Global, e os dados obtidos pelos processamentos, confrontados com os levantamentos decampo. Como resultados, o algoritmo Minimum Distance alcançou melhor desempenho (99,28% de acurácia) para o mês de setembro de 2017, e 2,44% de grau de severidade da sigatoka-amarela, em comparação ao levantamento de campo, que resultou em grau de infecção de 1% a 5%. Para os meses de outubro e novembro, o algoritmo Maximum Likelihood obteve 89,77%e 78,76% de acurácia, se aproximando dos valores levantados em campo, demonstrando que as ferramentas de monitoramento de manchas foliares podem ser realizadas por meio de técnicas de sensoriamento remoto, aprendizagem computacional e imagens pancromáticas de alta resolução espacial.

The objective of this work was to assess the incidence of Yellow Sigatoka in banana plants cultivated with deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur or boron. The experimental design was a randomized complete block with 8 treatments, 4 repetitions and 1 plant per repetition. The treatments were supplied in solution culture and consisted of all the nutrients (control) or nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S) or boron (B) deficiency. Leaves 1 and 2 were inoculated on the abaxial surface with a suspension of conidia and assessed every 5 days to with a total of 5 assessments. The average number of lesions were integrated for the area under the disease progress curve (AUDPC). The greatest AUDPC occurred in plants deficient in K, N, P, S, or Mg. Plants deficient in N, P, K, Ca, Mg, S or B had lower leaf contents of these nutrients and showed morphological changes expressed in visual deficiency symptoms. Thus, banana plants deficient in K, N, P, S or Mg had a greater incidence of Yellow Sigatoka, compared with plants with full nutrients and plants deficient Ca or B.

This study analyzed the spatial distribution of Yellow Sigatoka Leaf Spot relative to soil fertility and plant nutritional status using geostatistics. The experimental area comprised 1.2 ha, where 27 points were georeferenced and spaced on a regular grid 18 × 18 m. The severity of Yellow Sigatoka, soil fertility and plant nutritional status were evaluated at each point. The spherical model was adjusted for all variables using restricted maximum likelihood. Kriging maps showed the highest infection rate of Sigatoka occurred in high areas of the field which had the highest concentration of sand, while the lowest disease was found in lower areas with lower silt, organic matter, total exchangeable bases, effective cation exchange capacity, base saturation, Ca and Mg in soil, and foliar sulfur (S). These results may help farmers manage Yellow Sigatoka disease more effectively, with balanced fertilization and reduced fungicide application. This practice minimizes the environmental impact and cost of production while contributing to production sustainability.

Mycosphaerella musicola produces various toxins known to play a key role in pathogenicity and disease development. In our study secondary metabolites produced by M .musicola was extracted and investigated using different parameters. The investigation was aimed to understand the phytotoxic resistance of locally growing different Musa genotypes (AB-Elakki (ELA), AAA-G9 (G9) and AAB-Nanjangud Rasa Baley (NRB)) against the crude extract and partially purified lipophilic TLC fractions extracted from the culture filtrates of M. musicola. Susceptible and resistant banana genotypes against the crude extract and partially purified fractions were analyzed by electrolyte leakage assay and leaf puncher assay. The results revealed that the crude extract and TLC fractions showed varied phytotoxicity among the banana leaves belonging to different age groups and different genotypes. Phytotoxicity studies allowed us to observe that ELA and G9 exhibited resistance to crude extract and TLC fractions, indicating that these genotypes are resistant to initial M. musicola infection.

Among the diseases affecting banana (Musa sp), yellow Sigatoka, caused by the fungal pathogen Mycosphaerella musicola Leach, is considered one of the most important in Brazil, causing losses throughout the year. Understanding the genetic structure of pathogen populations will provide insight into the life history of pathogens, including the evolutionary processes occurring in agrosystems. Tools for estimating the possible emergence of pathogen variants with altered pathogenicity, virulence, or aggressiveness, as well as resistance to systemic fungicides, can also be developed from such data. The objective of this study was to analyze the genetic diversity and population genetics of M. musicola in the main banana-producing regions in Brazil. A total of 83 isolates collected from different banana cultivars in the Brazilian states of Bahia, Rio Grande do Norte, and Minas Gerais were evaluated using inter-simple sequence repeat markers. High variability was detected between the isolates, and 85.5% of the haplotypes were singletons in the populations. The highest source of genetic diversity (97.22%) was attributed to variations within populations. Bayesian cluster analysis revealed the presence of 2 probable ancestral groups, however, showed no relationship to population structure in terms of collection site, state of origin, or cultivar. Similarly, we detected noevidence of genetic recombination between individuals within different states, indicating that asexual cycles play a major role in M. musicola reproduction and that long-distance dispersal of the pathogen is the main factor contributing to the lack of population structure in the fungus.

In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled over 158,000 tons in 2011. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and Mycosphaerella musicola, respectively, are responsible for significant losses of this crop, due to the high susceptibility of the most important cultivars. Diploid, triploid and tetraploid hybrids were introduced from international breeding programs for evaluation in Isabela, Puerto Rico. Accessions were established in the field in a randomized complete block design and were evaluated over two cropping cycles (2007–2010) for response to BLS and agronomic traits. Significant differences (P = 0.05) in BLS severity were observed among accessions throughout both crop cycles and were most pronounced at harvest. When averaged across production cycles, severity indices at harvest ranged from very resistant (20% of the leaf surface affected) for ‘FHIA 02’ to extremely susceptible (97%) for ‘Grand Nain’. Yield attributes varied widely among the accessions, including mean bunch weights (6.9–41.0 kg), numbers of hands per bunch (6.6–13.4), and the numbers of fruit per bunch (57.0–239.2). Several accessions, mainly from the Fundacion Hondurena de Investigacion Agricola (FHIA), were BLS resistant and had short pseudostems, and large bunches. They could potentially replace susceptible cultivars in commercial production or play roles in a nascent organic market.

Banana fruits are harvested and marketed in the green stage. Green Life (GL) is the number of days between harvest and initiation of the ripening process, representing the time available to commercialization. Sigatoka leaf spot disease (SLSD), caused by the fungus Mycosphaerella musicola, is one of the main foliar diseases of banana production that leads to early ripening of the fruit, thus reducing the GL. The aim of this work was to determine whether removal of necrotic leaves could limit the effect of SLSD on fruit GL. Plants were classified according to four SLSD infestation levels, based on estimation of necrotic leaf area at flowering. GL of fruits was measured at 13°C, simulating the storage conditions during shipping, using two different treatments: plants with no leaf removal and plants with necrotic leaves removal (1 month before harvest). Higher SLSD infestation levels were associated with reduced GL values, reaching almost zero for the highest infestation level when leaves were not removed. However, with removal of necrotic leaves, GL increased over that of the control treatment (no leaf removal), and GL reached values greater than 40 days even for the highest infestation levels. Analyses of variance followed by Newman-Keuls tests (5% threshold) were conducted to compare different infestation levels among treatments. The removal of necrotic leaves 1 month before harvest considerably limited and, in some cases, suppressed the effect of SLSD on fruit GL at disease severity levels as high as 45% at flowering. In conclusion, pre-harvest removal of M. musicola-infected leaves represents a simple and effective cultural practice that may facilitate increased production of exportable bananas, when chemical control is not desired, not possible, or not efficient. (Resume d'auteur)

The release of new sweet-acid banana cultivars resistant to black leaf streak, Sigatoka leaf spot and Fusarium wilt is important for domestic markets in tropical and subtropical countries. Common current breeding strategies consist of selecting tetraploid AAAB hybrids directly from crosses between AAB sweet-acid cultivars pollinated with AA clones carrying disease-resistance genes. However, this crossing pathway is hampered by low gamete fertility and the rare occurrence of desired 2N gametes on the AAB female side (N=3X=33 chromosomes). We propose an alternative pathway which aims to create new triploid hybrids directly from AB landraces. Natural AB clones are sterile but their AABB tetraploid counterparts obtained by colchicine treatment are fertile. This gamete fertility was made profitable in crosses with AA and BB accessions to generate AAB and ABB hybrids. We present here agronomical results of various progenies involving an in vitro synthesized tetraploid 'Kunnan' (AABB) and several AA and BB clones. These first results suggest the very high potential of this new strategy for the release of wellperforming new hybrids combining higher productivity, disease resistance and better fruit quality. Hybrids with a high added-value, produced in this way, could be made available for evaluation within the ProMusa network. (Resume d'auteur)

Bananas and plantains (Musa spp.) are among the world’s most important crops and are considered as a poor man’s crop in tropical and subtropical countries. For this reason, they play a very important role in tropical regions’ food security. Several pathogens throughout the tropical areas of the world have become a threat for production, including “black sigatoka” (Mycosphaerella fijiensis Morelet) which is the most damaging disease for Musa plantations in Cuba. It is present in all areas of the country, and it replaced “sigatoka disease” (Mycosphaerella musicola) as the main threat. Chemical control and cultural practices reduce damages, but they are not solving the problem. Genetic variations are the basic tools to develop new cultivars with better traits, such as tolerance against various environmental stresses, resistance against pests and diseases, and improved yield and quality. Tissue culture techniques offer the opportunity for variation induction, handling of large plant populations using established selection methods, and rapidly cloning selected variants. All these strategies can increase the efficiency of mutagenic treatments and subsequent screening of mutant materials. Somatic embryogenesis (SE) is also an excellent system for clonal propagation and mutation induction. The present chapter describes a protocol on how to use embryogenic cell suspensions (ECS) in plantain (Musa spp.) using both in vitro gamma irradiation and plant regeneration in order to achieve genetic improvement. The process involves a series of steps to properly select ECS for irradiation and the posttreatment handling for plant regeneration as well as mutant selection during acclimatization phase and under field conditions.

One of the major diseases affecting banana is Sigatoka or leaf spot disease that comprises three species, Mycosphaerella fijiensis , Mycosphaerella musicola and Mycosphaerella eumusae . Plants have a large number of defence related genes which trigger a cascade of defense responses that halt the spread of pathogens. Knowledge of the diversity present in genes related to the defense against Sigatoka disease will be useful in developing disease resistant banana cultivars. The defence genes of all sterile commercial banana cultivars (AAA genomes) are considered to have arisen from a similar gene pool belonging to the Musa acuminata complex. The objectives of this study were, (i) to assess the disease response of twelve banana cultivars to M. eumusae, (ii) to assess the level of polymorphisms in selected genes associated with defence against Sigatoka in banana, and (iii) ascertain if this polymorphism was related to levels of resistance to M. eumusae . Defence genes reported to act in response to M. fijiensis were selected and related to the response of M. eumusae . The genetic diversity of selected defence gene analogs (DGA) was assessed using degenerate primers designed from conserved motifs in the aligned amino acid sequences from known resistance genes. Highly polymorphic amplicon profiles for DGAs were selected for comparison. Cluster analysis was used to differentiate to some extent, cultivars considered as resistant/susceptible to M. eumusae . Specific amplicons from the profiles of phenylalanine ammonia-lyase (PAL), iron superoxide dismutase (FeSOD) and ascorbate peroxidase (APX) were unique to a group of resistant cultivars and could act as markers for resistance to M. eumusae . Keywords: Banana, defence gene analogs, polymorphism

An understanding of the progression of a disease is important in the adoption of control strategies as well as the evaluation of their efficacies. Temporal analysis is especially useful because it integrates the evolution of the interaction between the components of the pathosystem, as expressed by the accumulated data on the incidence and severity of disease and depicted by the disease progression curve. Within a given patho-system, the dispersed airborne spores are important components in the progress of plant disease epidemics. Our aims were to evaluate the temporal dynamics of yellow Sigatoka in a banana plantation located in Coronel Pacheco, MG, Brazil, and to assess the aerobiology of Mycosphaerella musicola spores throughout the year. During the rainy season, we observed intense disease progression concomitant with high rates of leaf emission, which caused rapid reversal of the severity peaks after the maximum rates were reached. The yellow Sigatoka progress curve showed two peaks of extreme severity. The first, which occurred during the rainy season, was predominantly caused by a high concentration of conidia. The second, which occurred during the dry season, was predominantly caused by a high concentration of ascospores in the air. The ascospore concentrations were correlated with the severity of the disease 29 days later, indicating the average latency period of the disease in that region. The patterns of the severity curves for both peaks fit the monomolecular model, and the progression rates were higher during the rainy season than the dry season. The spore concentrations were the same at the two evaluated heights. In all evaluations, it was observed a higher concentration of ascospores than of conidia, with the greatest ascospore concentrations occurring during the early hours of the day and the greatest conidia concentrations occurring later, after the dew has dropped from the leaves.

Kenya has experienced a decline in banana (Musa spp.) production during the last two decades. This can be attributed mainly to an increase in the prevalence of pests and diseases due to the limited practice of effective control. The main pests and diseases of concern are Fusarium wilt (caused by Fusarium oxysporum f. sp. cubense), black leaf streak and Sigatoka leaf spot (caused by Mycosphaerella fijiensis and Mycosphaerella musicola, respectively), banana Xanthomonas wilt (Xanthomonas campestris pv. musacearum), the banana weevil Cosmopolites sordidus, and the burrowing nematode (Radopholus similis). Since neither a formal system nor standards exist to regulate planting material quality, farmers frequently plant untreated, thus potentially infested sword suckers, aggravating the problem. There is a need to develop standards and codes of practice that will ensure access to certified healthy planting materials of improved banana germplasm. Micro-propagation (tissue culture) has gained popularity for rapid production of clean banana planting material. However, updated standards and codes of practice are needed to guide the application of this method to ensure good quality. Similarly, the capacity to use tissue culture to generate clean planting material must be developed in tandem with a virus indexing mechanisms for such material, as well as imported material, to monitor and restrict the movement of viruses. Rapid detection of pests and diseases during import inspections and certification of nursery-propagated materials is essential for the prevention of the introduction, and spread of pests and diseases of quarantine importance. The development of rapid and inexpensive diagnostic kits will facilitate quick decision-making. In this regard, Kenya Plant Health Inspectorate Service (KEPHIS), the regulatory agency responsible for seed and plant material quality and plant quarantine, continues to be a key partner in initiatives to multiply, exchange, distribute, import and export banana propagation material. This paper provides an overview of the regulatory measures necessary for sustainable development of the banana subsector of horticulture in Kenya.

An antagonistic bacterial strain B106 was isolated from the rhizospheric soil of a banana plant in Nanning city, Guangxi, China, and identified as Bacillus subtilis based on its 16S rDNA sequence homology with the related bacteria from GenBank as well as physiological and biochemical characters. The cultural conditions were optimized for enhancing the efficacy of the antagonist against banana leaf spot caused by Pseudocercospora musae (teleomorph: Mycosphaerella musicola) and post-harvest anthracnose by Colletotrichum musae. The optimized cultural condition for strain B106 to express higher antagonistic activity against P. musae was the combination of 31 C, pH 6.0, EM medium and 5-day-incubation. However, the optimized cultural condition for the bacterium to produce higher biomass was the combination of 31–34 C, pH 6.5, EM medium and 3-day-incubation. The results based on greenhouse tests showed that 72.3% efficacy of the antagonist in controlling the banana leaf spot disease was obtained 10 days after pathogen inoculation. The efficacy of strain B106 (1 � 10 8 CFU ml � 1 ) in controlling both banana leaf spot diseases in the field and anthracnose disease at post-harvest stage was 48.3% and 48.6%, respectively, under the optimized cultural condition for the strain to express higher antagonistic activity. The experimental data indicated that the antagonistic strain was a promising biocontrol agent against the banana diseases.