Commercial Banana Plantations Research Articles

Commercial banana and macadamia plantations in a savanna matrix support high levels of arthropod diversity

Expansion and intensification of agroecosystems is one of the major causes of habitat loss in the savanna biome in South Africa. As such, this study sought to determine the influence of commercial subtropical fruit plantations (banana and macadamia) on species richness, abundance, and composition of surface-active arthropods compared to the savanna biome. Given that pesticides and herbicides are applied from spring to early autumn in banana and macadamia plantations, we sampled in winter to reduce the potential impact of pesticides and herbicides. Surface-active arthropods were sampled using pitfall traps. Habitat type did not affect species richness and abundance of ants and spiders, as well as species richness of beetles. However, significantly greater abundance of beetles was recorded in the macadamia plantation compared to the banana and savanna. This could have been due to greater abundance of herbivorous beetles and other insects, which would have increased the diversity of predatory beetles. Furthermore, unlike the banana plantation, the macadamia plantation was characterised by a deep leaf litter layer and the presence of weeds and grasses, which probably increased abundance of beetles. Species composition indicated that the studied arthropod taxa associate with specific habitats, as demonstrated by the three habitats supporting different species composition. Despite savanna habitat not supporting high species richness or abundance of surface-active arthropods, we recorded the highest number of unique species of ants and spiders in the savanna rather than in the plantations. These results highlight the importance of natural landscapes in conservation of surface-active arthropods.

Natural occurrence of Beauveria caledonica, pathogenicity to Cosmopolites sordidus and antifungal activity against Fusarium oxysporum f. sp. cubense

Entomopathogenic fungi can provide a set of ecological services, such as suppressing arthropod pests and plant pathogens. In this study, novel indigenous Beauveria caledonica (Bc) strains were isolated from naturally infected banana weevils (Cosmopolites sordidus) occurring in commercial banana plantations in Brazil. The prevalence of infection by Bc strains on field-caught C. sordidus ranged from 1.3% to 12.9%. Similar to the Beauveria bassiana strains tested, none of the Bc strains caused more than 50% weevil mortality at a concentration of 1 × 108 conidia ml-1 . Bc strain CMAA1810 caused the highest mortality in C. sordidus and had enhanced insecticidal activity when formulated with an emulsifiable oil. In paired co-culture assays, this same strain showed a significant growth-inhibitory effect on the causal agent of Fusarium banana wilt (Fusarium oxysporum f. sp. cubense, Foc) of twofold magnitude compared with the control. Cell-free crude filtrates derived from the red-pigmented culture broth of Bc (CMAA1810) strongly reduced Foc conidial viability, and this inhibitory activity was inversely related to the age of the Bc culture. Crude concentrated filtrates from 4-day-old cultures exhibited the strongest antifungal activity (13-fold) compared with untreated Foc conidia. The abundant compound identified in the crude filtrate of Bc was oosporein (1,4-dibenzoquinone) present at a concentration of 0.829 ± 0.018 mg g-1 dry matter, and the antifungal activity of the filtrate was demonstrated. These results indicated that Bc strains might have the potential to manage both C. sordidus and Foc, two of the major phytosanitary problems in banana crops worldwide. Further research under field conditions using suitable formulations of virulent Bc strains in combination with the metabolite oosporein is needed to evaluate their efficacy in the management of C. sordidus and Foc in banana plantations. © 2022 Society of Chemical Industry.

Development of Banana Peduncle Juice Extractor For Ethanol and Fiber Production

Banana (Musa acuminata C.) peduncle is a waste byproduct of commercial banana plantations in the Philippines. Several studies proved the potential of utilizing this agricultural waste as raw material to produce ethanol, and the practical applications of its high-quality fiber. However, mechanical juice extraction was found to limit production as machines used are intended for other commodities, which may not meet functionality requirements for optimum performance. To meet the need, a juice extractor was developed to extract juice from banana peduncle without rupturing its fiber structure for the purpose of ethanol production and fiber recovery. The machine employed a system of crushing rolls as extraction mechanism and was studied under the effects of roll rotational speed (50, 70, and 90 rpm) and crushing load (0.8, 1.2, and 1.6 kN). Optimum performance of the machine was obtained under the optimal setting, 71.4 rpm and 0.8 kN, which resulted to input capacity (307.24 kg/h), juice extraction rate (82.92 kg/h), juice recovery (26.08%), extraction losses (4.21%), extraction efficiency (18.46%), fuel consumption rate (0.391 L/h), fiber extraction rate (54.83 kg/h), and fiber recovery (42.29%). ANOVA reveals that higher roll rotational speed and lower crushing load increases input capacity, juice and fiber extraction rates, and fiber recovery. Lower roll rotational speed and higher crushing load increases juice recovery and extraction efficiency. Higher roll rotational speed increases extraction losses while higher crushing load increases fuel consumption rate. No significant effect was found on the °Brix of extracted juice and on the tensile strength of the fiber. Ethanol analysis showed that the fermented juice contains 10-11% ethanol v/v while fiber tests showed tensile strength values approximate to 300 MPa.

Application of biofertilizer directly on ‘Terra Maranhão’ platain bunch for productivity gain

Abstract Advances in production systems always aim at finding alternatives to improve crop productivity. One of the recent practices adopted in commercial banana and plantain plantations refers to the application of liquid fertilizers in bunches in order to increase productivity. This research aimed at verifying whether the use of biofertilizers based on pure vinasse or associated with other chemical fertilizers would provide morphophysiological changes in fruits or increase the productivity of ‘Terra Maranhão’ plantain cultivars. In order to carry out this project, a randomized block design with 6 treatments and 3 replicates was set up in a commercial crop and the postharvest production and quality characteristics of ‘Terra Maranhão’ plantain fruits were evaluated. The results showed that the morphophysiological characteristics of freshly harvested fruits that impact productivity such as the fruit weight and bunch weight were affected by treatments, as the postharvest characteristics of ripe fruits were little affected by the application of fertilizers in bunches, except for the SST content. It could be concluded that the crop yield increased significantly by 17% when using mixture of vinasse, potassium chloride and urea; however, this treatment caused significant reduction of 1.3 ºBrix compared to control.

Correlation of banana productivity levels and soil morphological properties using regularized optimal scaling regression

Soil morphological properties described in the field, such as texture, consistence or structure, provide a valuable tool for the evaluation of soil productivity potential. In this study, we developed a regression model between the soil morphological variables of banana plantations and a crop Productivity Index (PI) previously developed for the same areas in Venezuela. For this, we implemented categorical regression, an optimal scaling procedure in which the morphological variables are transformed into a numerical scale, and can thus be entered in a multiple regression analysis. The model was developed from data from six plantations growing “Gran Nain” bananas, each with two productivity levels (high and low), in two 4-ha experimental plots, one for each productivity level. Sixty-three A horizons in thirty-six soils were described using 15 field morphological variables on a nominal scale for structure type, texture and hue, and an ordinal scale for the rest (structure grade, structure size, wet and dry consistence, stickiness, plasticity, moist value, chroma, root abundance, root size, biological activity and reaction to HCl). The optimum model selected included biological activity, texture, dry consistence, reaction to HCl and structure type variables. These variables explained the PI with an R2 of 0.599, an expected prediction error (EPE) of 0.645 and a standard error (SE) of 0.135 using bootstrapping, and EPE of 0.662 with a SE of 0.236 using 10-fold cross validation. Our study showed how soil quality is clearly related to productivity on commercial banana plantations, and developed a way to correlate soil quality indicators to yield by using indicators based on easily measured soil morphological parameters. The methodology used in this study might be further expanded to other banana-producing areas to help identify the soils most suitable for its cultivation, thereby enhancing its environmental sustainability and profitability.

The use of UAVs in monitoring yellow sigatoka in banana

Monitoring pests and diseases is an extremely important activity for increasing productivity in agriculture. In this scenario, remote sensing, coupled with techniques of machine learning, offer new prospects for monitoring and identifying characteristic specific patterns, such as manifestations of diseases, pests, and water and nutritional stress. The aim was to use high spatial resolution aerial images to monitor the extent of an attack of yellow sigatoka in a banana crop, following the basic assumptions of identification, classification, quantification and prediction of phenotypic factors. Monthly flights were carried out on a commercial banana plantation using an unmanned aerial vehicle, equipped with a 16-megapixel RGB camera (GSD of 0.016781 m pixel−1). Five classification algorithms were used to identify and quantify the disease while field evaluations were also made following traditional methodology. The results showed that, for September 2017, the Support Vector Machine algorithm achieved the best performance (99.28% overall accuracy and 97.13 Kappa Index), followed by the Artificial Neural Network and Minimum Distance algorithms. In quantifying the disease, the SVM algorithm was more effective than other algorithms compared to the conventional methodology used to estimate the extent of yellow sigatoka, demonstrating that the tools used for monitoring leaf spots can be handled by remote sensing, machine learning and high spatial-resolution RGB images.

Effect of nematicide rotation on banana (Musa AAA cv. Williams) root nematode control and crop yield

The effects of nematicide rotation on banana (Musa AAA cv. Williams) root weight, root nematode control, and crop yield were compared in a commercial banana plantation in Ecuador, testing six treatments in a randomized complete block design with six replicates. Treatments consisted of two, three and four different nematicide cycles per year plus the untreated control. Regarding the untreated plants and averaging the 24 root nematode samplings after treatment application, the nematicide applications reduced significantly R. similis (P<0.0001) between 20 and 49%, Helicotylenchus spp. (P<0.0001) between 31 and 51%, and total nematode populations (P<0.0001) between 29 and 49%. Accordingly, in the treated plants, there was an increase between 16 and 21% in living root weight (P=0.0003), and its percentage (P<0.0001) reached between 74.5 and 81.7% in the follower suckers. In addition, the death of roots by nematodes decreased (P=0.0009) between 20 and 46%. At harvest, nematicide applications increased bunch weight (P=0.0002; P=0.0467), ratio (P=0.0003 at 12 months), ratooning (P<0.0001; P<0.0001) and the number of boxes of 18.14 kg (P<0.0001; P=0.0005) per hectare per year at 12 and 24 months after treatment application, respectively. Plants treated with nematicides increased yield between 671 and 1,158 (12.2 - 21 t) and the number of boxes of 18.14 kg per hectare per year also increased between 545 and 1,046 (9.9 - 19.0 t), which resulted in a net profit between US $3,266 - $5,750 and between US $2,587 and $5,144 per hectare per year at 12 and 24 months after treatment application, respectively.

Factors affecting the biological control of the spiralling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae) in banana plantations in Costa Rica: a study case

ABSTRACTA study was conducted to reveal the causes for Aleurodicus dispersus outbreak in commercial banana plantations in Costa Rica. Biotic and abiotic factors affecting the abundance of the spiralling whitefly were determined. Four nymph parasitoids and nine predators were found to affect A. dispersus population. Seventeen families of host plants for A. dispersus in the banana area were identified, allowing the whitefly to reach a high reproductive and dispersal rate and pest status in short periods. The use of nematicides during the dry season was the key factor for mortality of natural enemies responsible for maintaining pest populations under economic levels.

Spatial Distribution and Sequential Sampling of the Banana Root Borer

The banana root borer, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), is a major pest in many banana (Musa spp.)‐producing regions of the world, causing yield losses of up to 100%. The aims of this study were to define the spatial distribution pattern of C. sordidus in banana plantations, to determine the probability distribution model that best describes the sampling data, and to develop a sequential sampling plan for this pest. Aggregation was investigated using aggregation indices and theoretical frequency distributions. To quantify the number of insects, 80 traps were distributed in a commercial banana plantation with an area of 4 ha and inspections were performed every 2 wk from 2005 to 2008. The sequential sampling plan was based on Wald's sequential probability ratio test. The calculated indices indicated moderate aggregation, with a common k parameter of the negative binomial distribution equal to 3.29. The best model for predicting the spatial distribution of the insects was the negative binomial distribution, which fit 93% of the inspections, followed by the Neyman Type A distribution, which fit 90% of the surveys, and Poisson's distribution, which fit only one survey. A sequential sampling plan was generated with Type I and II error rates of 5%, for which 19 was the maximum expected number of samples required to reach a decision for an infestation mean of approximately 3.7 insects per trap. The validation showed that the constructed plan is reliable and provides correct recommendations for decision‐making in pest control. The banana root borer has an aggregated spatial distribution in the field. Negative binomial distribution is the best model to explain species spatial pattern. A sequential sampling plan was developed and validated. The sequential sampling plan showed reliable decision rates. The sequential sampling plan showed a reasonable number of required sample units.

Chemical and microbiological interactions between soils and roots in commercial banana plantations (Musa AAA, cv. Cavendish)

A study was performed to determine the relationships between soil chemical and microbiological conditions and how they impact soil production. The study was carried out on six Costa Rican commercial banana farms with high, medium and low productivity. In each of the farms sector with relatively good and poor crop development were identified. In these sectors, microbiological and chemical properties of the soil and banana roots were characterized in the fertilization band, the interrow, and the rhizosphere. In addition, crop performance was evaluated in terms of plant height, the vigour of the pseudostem, and the number of hands per bunch. Higher biometric values were found in the sectors with good development, regardless of the farm, than in those with poor plant development. The pH was significantly lower in the sectors with poor crop performance in both the fertilization band and the rhizosphere. The soil chemical and microbiological properties differed significantly between the good and poor performing areas, but also between the fertilization band, interrow, and rhizosphere. Bacteria, fungi and actinomycetes were less in roots from plants in the sectors with poor performance. Chemical and microbiological conditions in the soil influenced the roots conditions according with the banana plant development and production. This study shows the complex interactions between soil chemical and microbiological conditions and how they affect banana production.

The effect of screen type on crop micro-climate, reference evapotranspiration and yield of a screenhouse banana plantation

Most banana screenhouses are currently equipped with transparent screens, with a nominal shading of 8–15%. Two types of screens are widely used, woven or knitted, which differ in their texture and hence in their radiative and aerodynamic properties. These differences may induce different micro-climatic conditions and hence different atmospheric water demand, plant response and yield.We have investigated four types of screens based on different shading levels (8%, 10% or 13%) and different screen textures (woven or knitted). A large commercial banana plantation in Northern Israel was covered with patches of the four different screen types, each in 4–5 replicates, randomly located. Air velocity, temperature, humidity and net radiation were measured simultaneously below two out of the four screen types: the 10% woven and 10% knitted. The results showed that both the net radiation and air temperature were similar under these two screens. Nevertheless, under the knitted screen the horizontal mean air velocity was 18% higher and the specific humidity 8% lower than under the woven screen. Leaf lamina tearing (typical wind damage) and estimated reference evapotranspiration were higher under the knitted screen; the latter mainly during the fall–winter season. However, the horticultural measures of flowering and fruit yield characteristics were the same under all four screen types, with results typical of screenhouse banana plantations in this region. Hence, the results suggest a potential increase in water use efficiency under the woven as compared to the knitted screen.

Performance of tissue-cultured versus sucker-derived East African highland banana (Musa AAA-EA) under high and low input systems in Uganda

Banana (Musa spp.) is a vegatatively propagated crop and the type of planting material is of great importance for the productivity of banana plantations. Traditionally, sucker derived planting materials have been used to establish banana plantations but there is a risk of transmitting pests such as plant-parasitic nematodes with untreated suckers. Tissue cultured banana plants are pest-free and widely grown in commercial dessert banana plantations but are not common agricultural practice under East African conditions. This study aimed at evaluating the agronomic performance and nematode infestation levels of sucker-derived and tissue cultured planting material of the East African highland cooking banana cultivar Nabusa (Musa spp., genome group AAA-EA) over five crop cycles. A field trial was conducted in Central Uganda using tissue culture plants, untreated suckers, pared suckers or pared and hot water treated suckers.All plants were cultivated under mulched or non-mulched conditions to represent high or low input systems, respectively. Mulch in general improved agronomic performance of banana. Type of planting material also influenced plant growth and yield. Tissue culture plants developed faster and yielded higher during the first crop cycle than sucker-derived material but not thereafter. Plant height and bunch weight of untreated suckers was inferior to all other planting material from the third crop cycle onwards. All mulched plants flowered earlier in all crop cycles. Duration from planting to the first harvest was less for tissue-cultured plants, but planting material had no influence on days to harvest from the third crop cycle onwards. Nematode densities were higher in roots from plants grown from untreated suckers than all other planting material, with Radopholus similis consistently recovered in greater densities than Helicotylenchus multicinctus across treatments. Mulching had no influence on nematode densities, root necrosis, number of root base lesions or number of dead roots. Nematode associated damage was higher in plants from untreated suckers but did not differ among tissue-cultured and pared and hot water treated or pared sucker plants. This study demonstrates the benefits of using clean planting material for cooking banana over five consecutive crop cycles and confirms the beneficial effects of mulching. In order to achieve high banana yields over several crop cycles, clean planting material needs to be supported by the application of mulch. However, this study shows that the application of mulch will not offset the detrimental effects of plant parasitic nematode-infected sucker planting material.

Necrotic leaf removal, a key component of integrated management ofMycospaerellaleaf spot diseases to improve the quality of banana: the case of Sigatoka disease

Introduction. Bananas are harvested at the green preclimacteric stage prior to sale. The time between harvest and the initiation of the natural ripening process is called green life. Black Leaf Streak Disease and Sigatoka Disease are the main foliar diseases affecting banana production. Sigatoka Disease (SD) is due to Mycosphaerella musicola , which frequently causes early ripening in commercial banana plantations, considered as an important source of damage. Our work aimed at determining the effectiveness of the removal of necrotic leaves, one month before harvest, on recovering banana quality arising from SD-infested plants. Materials and methods. Banana plants (totaling 80) at the flowering stage were selected in an experimental plot. These plants were divided into two groups of SD infestation levels: level 1 (Severity Index at flowering 25%). We divided each group into two treatments: a treatment with no necrotic leaf removal and a treatment with necrotic leaf removal. Fruits were harvested at the same physiological age, at 900 degree-days. Fruit quality was characterized by weight, diameter, % of ripe fruit in the field and fruit green life. Results. Our results showed that the removal of necrotic leaves causes a reduction in size parameters but leads to a strong reduction in SD effects on the fruit maturity, thereby preventing premature ripening. Banana plants whose necrotic leaves were removed produced fruit with a very long green life. Discussion. Removal of necrotic leaves allows thwarting the negative effect of SD on fruit physiology. This shows that the presence of necrosis during the last month of fruit growth is responsible for this fruit physiological modification characterized by early ripening. Conclusion. Removal of necrotic leaves one month before the date of harvest may be a technique that can limit production losses when the infestation level by SD is high. (Resume d'auteur)

Análise de risco da ocorrência de Sigatoka-negra baseada em modelos polinomiais: um estudo de caso

Black Sigatoka (Mycosphaerella fijiensis) threatens the banana trade in most of world's producing areas, damaging the production and bringing significant financial loss. It is necessary to study the plant's susceptibility in the various developmental stages and climatic conditions that favor the disease occurrence. This paper presents a probabilistic model based on polynomial functions for estimating the risk of Black Sigatoka occurrence. A case study was developed in a commercial banana plantation located in Jacupiranga, Vale do Ribeira, SP, Brazil, considering the weekly monitoring of the disease's state evolution (EE), time series of meteorological data and remote sensing data. Georeferenced risk maps were prepared for different dates. We obtained a model to estimate the evolution of the disease from satellite imagery, with a coefficient of determination of 0.9. This methodology was developed for the detection of times and locations that have favorable conditions to the occurrence of Black Sigatoka and can be applied, with appropriate adjustments for different locations, to assess the risk of disease occurrence in other areas of banana production.

Predicting the Benefits of Banana Bunchy Top Virus Exclusion from Commercial Plantations in Australia

Benefit cost analysis is a tried and tested analytical framework that can clearly communicate likely net changes in producer welfare from investment decisions to diverse stakeholder audiences. However, in a plant biosecurity context, it is often difficult to predict policy benefits over time due to complex biophysical interactions between invasive species, their hosts, and the environment. In this paper, we demonstrate how a break-even style benefit cost analysis remains highly relevant to biosecurity decision-makers using the example of banana bunchy top virus, a plant pathogen targeted for eradication from banana growing regions of Australia. We develop an analytical approach using a stratified diffusion spread model to simulate the likely benefits of exclusion of this virus from commercial banana plantations over time relative to a nil management scenario in which no surveillance or containment activities take place. Using Monte Carlo simulation to generate a range of possible future incursion scenarios, we predict the exclusion benefits of the disease will avoid Aus$15.9-27.0 million in annual losses for the banana industry. For these exclusion benefits to be reduced to zero would require a bunchy top re-establishment event in commercial banana plantations three years in every four. Sensitivity analysis indicates that exclusion benefits can be greatly enhanced through improvements in disease surveillance and incursion response.

Raoiella indica (Acari: Tenuipalpidae): an exploding mite pest in the neotropics

Major infestations of the flat mite species Raoiella indica Hirst affecting bananas, palms and other ornamental plants have been reported from the Caribbean islands, Mexico, FL (USA), Venezuela, Colombia and Brazil. Specimens from these localities were examined using traditional light microscopy and low-temperature scanning electron microscopy techniques. While little is known about the biology of this mite, its recent appearance in the Americas in both commercial coconut and banana plantations has raised concerns about its economic impact as an invasive pest.

How earthworm activities affect banana plant response to nematodes parasitism

The burrowing nematode Radopholus similis and the lesion nematodes Pratylenchus spp. are considered as major constraints to banana cultivation worldwide. As an alternative to the use of chemical pesticides in commercial banana plantations, the possible role of the earthworm Pontoscolex corethrurus was studied regarding the reducing harmfulness of the main plant-feeding nematodes of banana. The interactions among banana plants, plant-feeding nematodes and earthworms have been tested in a controlled experiment combining treatments including or not earthworms and nematodes, over a complete vegetative banana development cycle. The aim of the work was to evaluate how earthworm activity can affect the pathogenicity of the three main plant-feeding nematodes associated with dessert banana ( Musa spp. AAA group, cv. Cavendish) in Guadeloupe (French West Indies), R. similis, Pratylenchus coffeae and Helicotylenchus multicinctus. Results showed that damages caused by plant-feeding nematodes were lowered in the presence of the earthworm P. corethrurus; the population of plant-feeding nematodes did not decrease whereas root damage induced by nematodes was significantly reduced (50% reduction of root necrosis in the presence of earthworms). Moreover, in the presence of P. corethrurus, we observed a change of soil porosity. On the one hand, the burrowing activity of earthworms destroyed most of the initial structural porosity (mesobiotic pores, 3–300 μm) and on the other hand, they increased the volume of the finest structural pores diameter class (microbiotic pores, 0.3–3 μm). P. corethrurus also stimulated phosphorus mineralization. Soil bioturbation carried out by P. corethrurus could have enhanced the efficiency of microbial community that is involved in phosphorus bioavailability. This observation was corroborated by a higher phosphorus availability in earthworm casts (1386 ± 38 mg P kg −1 of dry matter in cast versus 778 ± 61 mg P kg −1 of dry matter in the soil compartment not influenced by earthworm activity), and a better plant phosphorus nutrition in the presence of earthworms. Phosphorus uptake resulted in a better plant nutrition and a better tolerance to plant-feeding nematodes. Besides, the reduction of the mesobiotic porosity by bioturbation could also have disturbed the nematodes activities during their soil phase and contributed to the reduction of their damage.

COMPARISON OF HOST REACTION TO FUSARIUM OXYSPORUM F. SP. CUBENSE TROPICAL RACE 4 AND AGRONOMIC PERFORMANCE OF SOMACLONAL VARIANT 'GCTCV-119' (AAA, CAVENDISH) AND 'GRAND NAINE' (AAA, CAVENDISH) IN COMMERCIAL FARMS IN THE PHILIPPINES

The original publication is available at www.actahort.org. Recent reports of the occurrence of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), causal agent of Fusarium wilt, in some commercial Cavendish banana plantations in the Philippines is of great concern to the Philippine banana industry. In an effort to mitigate the disease, 'GCTCV-119', a Foc TR4-resistant somaclonal variant of 'Giant Cavendish' selected by the Taiwan Banana Research Institute, was evaluated and compared with the commercial cultivar 'Grand Naine' in Foc-infested farms in Davao, Philippines. Isolates obtained from infected samples from these farms were previously typed as VCG1213/16, the vegetative compatibility group associated with TR4. Tissue culture-derived planting materials of 'GCTCV-119' and 'Grand Naine' were planted in randomised blocks in two farms where severe Fusarium wilt incidence was previously observed. After 12 months of disease incidence monitoring, 'GCTCV-119' showed no Fusarium infection, while 36 and 51% incidence was recorded for 'Grand Naine' in Calinan and Quibilan farms, respectively. Two years after establishment, 'GCTCV-119' plots in the Quibilan farm are still free from infection of Fusarium wilt while the 'Grand Naine' plots have been totally eradicated because of severe disease incidence. Agronomic and fruit quality traits were also recorded. Although 'GCTCV-119' proved to be highly resistant to TR4, it matured later and had a lower bunch weight and greater hand curvature resulting in more rejects when packed. 'GCTCV-119' is however sweeter as it has more total sugars and total soluble solids than 'Grand Naine'.

DEVELOPMENT OF A DIAGNOSTIC PROTOCOL FOR CUCUMBER MOSAIC VIRUS FOR SCREENING BANANA (MUSA SPP.) PLANTING MATERIAL IN IVORY COAST

Cucumber mosaic virus (CMV) is the primary virus affecting commercial banana (Musa spp.) plantations in Ivory Coast, with the disease also present within nursery systems. However, currently no virus indexing of planting material is performed for banana in the country. This current study attempts to quantify levels of detection of CMV within banana material using flinders technology associates (FTA) cards in order to identify a reliable and reproducible method suitable for local conditions. A suite of PCR primers were developed against CMV coat protein open reading frame (CP ORF) sequence available on GenBank. TaqMan assay generated comparable CT values with either FTA or cetyltrimethyl ammonium bromide (CTAB) derived templates and was able to detect CMV RNA in leaf samples. The conventional real time polymerase chain reaction (RT-PCR) assay, RNeasy and FTA derived RNA templates reliably amplified CMV, whilst CTAB-derived RNA gave variable results. The TaqMan ® reaction was much more sensitive than the conventional RT-PCR for CMV detection in banana leaf samples. The suitability of FTA cards as a matrix for virus nucleic acid capture provides scope for its use in the transportation of banana virus samples to laboratories for diagnosis and characterisation, circumventing constraints of time-related degeneration of sample integrity. Sequence data of the CMV CP ORF region of 16 isolates from Cote d'Ivoire clustered the isolates to CMV Sub-Group IA. This is the first successful application of Real-time PCR and FTA technology for a banana virus in Africa.

Nematode resistance in bananas: screening results on some wild and cultivated accessions of Musa spp.

Bananas cultivated for export all belong to Cavendish cultivars and are all recognized as very susceptible to nematodes, particularly to the burrowing nematode Radopholus similis and the lesion nematode Pratylenchus coffeae. Even if there have been many changes in the management of banana nematodes in large commercial banana plantations, chemical control still remains most often the last resort method to manage the nematodes, although the number of registered products is definitely declining. Therefore, nematode control though genetic improvement is gaining new interest worldwide. In this study, 55 banana accessions mostly diploids from the Musa acuminata genome group (AA) but including some triploid accessions (AAA), some diploids of the Musa balbisiana genome group (BB) and some interspecific hybrids (AAB, AB) were evaluated for resistance to four nematode species R. similis, P. coffeae, Meloidogyne incognita and M. arenaria. These experiments were conducted in a growth chamber under controlled conditions. All banana accessions were susceptible to nematode species, although many different levels of susceptibility were detected. This study confirmed the good resistance status to R. similis of some cultivars from the Pisang jari buaya and Pisang batuau subgroups and the partial resistance of 17 diploid accessions significantly different from the susceptible reference cv. Grande Naine. This study also showed that 12 diploid accessions exhibited a partial resistance to P. coffeae, including some usual or potential genitors belonging to the wild diploids subspecies burmannica (cvs. Long Tavoy 1 and 2) and burmannicoides (cv. Calcutta 4). No source of resistance to Meloidogyne spp. was found. These screening results, combining for the first time four nematode species, are discussed within the scope of banana breeding in order to produce parental diploid lines with single or combined nematode resistances and further develop triploids that can substitute existing susceptible commercial cultivars.