Volume 4 Special Issue 2 2010
Bananas, plantains and enset II

ISBN 978-4-903313-63-4

How to reference: Drar YO, Thompson AK (2010) Challenges for Certified Organic Banana Production in Eritrea. In: Tripathi L (Ed) Bananas, plantains and enset II. Tree and Forestry Science and Biotechnology 4 (Special Issue 2), 1-6

Guest Editor

Leena Tripathi

in co-operation with International Institute of Tropical Agriculture (IITA), Uganda

www.iita.org

CONTENTS AND ABSTRACTS

Yohannes Ogbalidet Drar (Eritrea), Anthony Keith Thompson (Eritrea/UK) Challenges for Certified Organic Banana Production in Eritrea (pp 1-6)

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Original Research Paper: The objective of the work was to investigate the constraints and prospects of growing organic bananas for export from Eritrea. The Government of Eritrea has encouraged the development of the banana industry but the local market is saturated and the world market is over supplied and it is difficult for new exporters to find a lucrative market. Therefore banana production is contracting. However, there is a possible market for organic bananas and therefore a need to identify the requirements for Eritrean bananas to be certified as organic producers. As a first step to achieve this major banana producing areas of Eritrea were surveyed and 45 banana growers were interviewed. Pest and particularly disease control are usually the major challenges in organic production therefore the incidence and infestation levels of the major pests: nematodes, weevils, viruses and cigar end rot were studied. Soil samples and a water sample were collected and analyzed for their chemical composition. Results showed that on the farms studied the nematode incidence ranged 20-372/100 g fresh root weight, with 17-58 nematodes/100 g of soil. No weevils were found in all the surveyed areas. The average Banana Bunchy Top Virus incidence was 3.3% and Cigar End-Rot was 3.6%. The soil was of medium to low soil fertility but with a good texture. Water quality was found to be suitable for irrigation of bananas. The levels of these pests and diseases indicated that bananas could be grown using the system currently used by Eritrean farmers without the chemicals that are not permitted by international regulations for organic production. Some preharvest, particularly soil fertility, and postharvest practices, particularly crown rot control and harvesting and handling systems, were identified as being required to improve yield, quality and out-turn, but it was concluded that from a technical point of view organic banana production and export could be established in Eritrea.

Dilip Nandwani (USA) Constraints in the Production of Banana (Musa spp.) in the Northern Mariana Islands (pp 7-10)

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Research Note: The Commonwealth of the Northern Mariana Islands consists of a group of islands in the western pacific north of Guam. Banana (Musa spp.) is one of the important subsistence food crops and contributes significantly to the dietary needs and food security of the population in the Commonwealth. Dwindling economy, droughts, tropical cyclones or typhoon, and availability of quality planting material are some of the factors affecting banana production. Research on the cultivation of improved varieties and tissue culture has demonstrated the benefits of quality planting material among the farming community. Tissue culture plants of new varieties of banana including Fundacion Hondurena de Investigacion Agricola, (FHIA) hybrids, have been introduced in to the Commonwealth from regional institution. Field trials of the FHIA cultivars were conducted for their resistance to insect pests, diseases and agronomic performance. The selected varieties of banana were identified as the economically and culturally important ones that have been tested for superior characteristics in the region. Preliminary findings of field evaluations of FHIA varieties into CNMI are encouraging and indicate promising results of tissue culture banana varieties. This article focuses primarily on the constraints of banana production in the Northern Marianas, control measures and the role of Cooperative Research, Extension and Education Service Department of the Northern Marianas College addressing the issues in the cultivation of banana. An account of insect pests and diseases and how other factors have influenced this economically and culturally important crop in Micronesia is also provided.

Erval Rafael Damatto Junior, Roberto Lyra Villas Bôas, Sarita Leonel (Brazil), Juan Cabrera Cabrera, Víctor Galán Saúco (Spain) Quality of Banana Fruit Produced in Different Locations (Greenhouse and Open Air) of the Canary Islands (pp 11-14)

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Original Research Paper: This work aimed to evaluate fruit quality and nutrient content of Cavendish banana cultivars produced under different greenhouse covers in Tenerife Island (Spain) and compare them with other bananas production regions in the island. Observation on fruit quality under greenhouse were carried out in the experimental station of Pajalillos of ICIA - Instituto Canario de Investigaciones Agrarias on a plot planted with in vitro plants of two cultivars (‘Grand Nain’ and ‘Gruesa’) in their fith crop cycle, cultivated under four green house covers: Celloclim (thermic plastic), 20 × 10 mesh, white mesh and 16 × 10 mesh. Data were also collected in open air cultivation in 3 different location of Tenerife: Cueva del Polvo, Hoya Meleque and Canaria Forestal. Nutrients levels in the dry mass of ‘Gruesa’ and ‘Grand Nain’ banana leaf did not show differences between cultivars nor among different greenhouse covers. The parameters analysed related to fruit quality were not also influenced by covers or cultivars and nor relevant differences were also detected between open air condition and greenhouse cultivation.

Jules Ntamwira, Dowiya Benjamin Nzawele, Dieudonné Katunga (Democratic Republic of Congo), Piet Van Asten, Guy Blomme (Uganda) The Effect of Application of Organic Matter during Planting on Growth of an East African Highland Cooking Banana Grown on Two Contrasting Soils in South Kivu, Eastern DR-Congo (pp 15-16)

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Short Communication: Highland bananas grown near the homestead in Eastern Democratic Republic of Congo receive organic household residues and are often mulched. Farmers also tend to allocate their best land for banana cultivation. However, due to an increased demand for bananas, farmers have started establishing banana plots on less fertile land. An experiment was conducted to assess plant growth on plots further away from the homestead and with minimal amounts of organic matter input. Two sites with contrasting soil fertility were chosen. Soil samples taken at the onset of the trial were analysed. The organic matter input consisted of Loudetia sp., the dominant weed species found on marginal soils, while Tithonia diversifolia was added to facilitate the decomposition of Loudetia sp. Pared lateral shoots of the east African highland cooking banana ‘Barhabesha’ (AAA-EA) were planted. The treatments consisted of 2 kg of organic matter added in the planting hole at planting, 2 kg of organic matter applied as mulch around the plant after planting, 1 kg of organic matter applied in the panting hole during planting and 1 kg of organic matter applied as mulch on the soil after planting. No organic matter was applied in the control. The following growth characteristics were assessed at 12 months after planting: plant height, total number of leaves formed and pseudostem circumference at the base of the plant. There was enhanced plant growth in the more fertile soil at Mulungu. Plant growth was enhanced with application of organic matter. Although this effect was more pronounced in the poor soil of Cijingiri, plant performance was generally so poor at this location that bananas cannot be considered a viable enterprise in such degraded soils.

Alfonso Vargas, Mario Araya (Costa Rica) Effect of Banana (Musa AAA cv. Williams, Cavendish subgroup) Planting Material on Plant Growth and Yield over Eight Crop Cycles (pp 17-25)

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Original Research Paper: A field experiment was conducted over eight crop cycles comparing whole water suckers (WWS) without root and leaf pruning with tissue-cultured (TC) plants, both planting materials with or without nematicide application on plant growth and yield variables. Averaging the eight crop cycles, TCplants produced heavier (P = 0.0005) bunches with greater number of hands (P = 0.0003) than those originated from WWS plants. The nematicide application did not affect any of those variables in any of both planting materials. Follower sucker height, girth and its number of broad leaves at flower emergence of its mother plant were similar in both planting materials and not affected by the nematicide application. Ratooning index did not differ between planting materials. Bunch weight (P = 0.0001), fruit tick (P = 0.0001), number of fruits in the second hand (P = 0.0001) and leaves at harvest (P = 0.0001) and ratooning index (P = 0.0001) differed among ratoon crops. The percentage of missing plants was higher (P < 0.0331) in WWS plants during the R0, R1 and R2. Between plants treated or untreated with nematicide the percentage of missing plants was similar and low. TC plants had lower R. similis than WWS, without differing between nematode control methods, and in the WWS the nematicide application resulted in 53% less nematodes (P < 0.0001) compared to the untreated control. The results encourage continuing with the use of tissue culture plants in areas new to bananas or replanting areas where the fruit is for export markets. However, for domestic consumption or even in plantations where the fruit is advocated to export markets, but if there are restrictions of TC plants by cost or availability, the results obtained with WWS show high potential for their use in frequently replanting areas, especially those areas sowing at high plant densities, where the demand of planting material is high. The WWS health should be improved taken them from plantations free of nematodes in order to reduce the nematode potential infection.

Martha M. Bolaños-Benavides, Luz Marina Melgarejo (Colombia) Enzymatic Activity (Dehydrogenase) in Rhizospheric Soil of Musa AAB: Relationship with Depth, Agricultural Management Crop and Plant Age (pp 26-29)

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Original Research Paper: The objective of this work was to evaluate the dehydrogenase activity in rhizosphere of Musa AAB at different depths of the soil, agronomic management and age of the crop, and analyze the relationship between the enzyme activity and some soil biology properties. The present investigation focused on assessing the dehydrogenase enzyme in a soil Pachic Melanudands of Quimbaya, Quindio, Colombia. The growing practices of agricultural management were chemical, traditional and agroecological. The samplings were conducted in the rhizosphere at 0-5, 5-10,10-20 and 20-30 cm depth, and the surveys were made at 6, 12 and 18 months taking into account the plant phenology. Dehydrogenase activity was higher in the first cm of soil profile. The activity depends of the management crop being the higher in the agroecological conditions and the age of the plant. The activity was related to biological properties of the soil. This investigation constitutes the first study of enzymatic dehydrogenase activity of soil in that grow Musa AAB in Colombia.

Abdou Tenkouano, Babatunde Olusegun Faturoti, Paul Kayode Baiyeri (Nigeria) On-farm Evaluation of Musa Hybrids in Southern Nigeria (pp 30-34)

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Research Note: Performance and adoption potentials of new Musa hybrids were tested in southern Nigeria. To this end, ten Musa hybrids and a local check were deployed to the plantain and banana growing belt of southern Nigeria through a farmer participatory approach. Participating farmers were identified in each of the 10 selected plantain-producing states in collaboration with the agricultural extension network, using criteria related to technical know-how, social status, and resource capacity. On-farm trials were established and maintained by the farmers with provision of planting materials and facilitation of access to required inputs by IITA. Data were collected on two consecutive growth cycles on phenological and yield traits as well as resistance to black Sigatoka. Farmers’ preference ranking of the test varieties was also recorded. Genotype by environment interaction effects were significant (P < 0.001) for all the traits evaluated. Agronomic performance across locations was best for FHIA-25 and FHIA-23 with respect to bunch weight and for PITA26 and PITA14 for crop cycling and resistance to black Sigatoka disease, with farmer’s preference going to PITA14 and PITA17. Thus, field performance did not always correspond with farmers’ preference, which appeared to be influenced by ethnic-based perception of the culinary uses and processing potential of the varieties.

Samuel Adelani Babarinde, Grace Oluwakemi Babarinde, Olaitan Abeke Olasesan (Nigeria) First Report of Infestation of Stored Plantain Chips by Trogoderma granarium Everts (Coleoptera: Dermestidae) in Southwestern Nigeria (pp 35-38)

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Original Research Paper: Plantain (Musa paradisiaca) chips were infested with varying levels (4, 8 and 12 adults) of Trogoderma granarium Everts (sex ratio 1:1) per 20 g chips. Uninfested plantain chips served as control. Data on chips weight loss due to T. granarium feeding and number of F1 larvae were taken at 3 and 6 months after infestation (MAI). Initial insect level significantly affected plantain chips weight loss and number of T. granarium larvae. At 3 MAI, chips that were infested with 12 adults suffered 9.5% weight loss and 63.0 larvae. These values were significantly (P < 0.05) higher than values (1.3% weight loss and 6.0 larvae) obtained when chips were infested with 4 adults. At 6 MAI, 66.0 larvae obtained in chips infested with 12 adults were significantly higher than values obtained when chips were infested with fewer T. granarium adults. Percentage weight loss was also highest when chips were infested with 12 T. granarium adults. The results indicate that T. granarium is a storage pest of plantain chips which fed on and utilized it for its reproductive biology.

Alfonso Martínez Garnica, Miguel Mayorga Pinzón (Colombia) Sigatoka Disease Severity Reduced by Agro Forestry and Production of Plantains under Those Conditions (pp 39-49)

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Original Research Paper: Plantain is an important cash crop of countries like Colombia. A traditional way of producing plantain is intermingled with trees in places close to farmhouses called “conucos”. Personal observations suggested such association had several advantages. So, a project of plantain production as a secondary crop under forests was evaluated. The first and most outstanding observation was a reduction of black Sigatoka severity. Tissue damaged for Sigatoka kept around 1 to 10% throughout the year while sunlight exposed plants had damages of 30 to 40%. Youngest leaf spotted remained around 6 to 13 while plants exposed to sunlight had YLS around 3. Changes on micro climate were responsible for the good answer. A lacking of dew condensation on leaves makes infection and incubation processes not to happen. Almost all trees behaved well in association with plantains. Nevertheless, three forest arrangements were considered better for plantains. First, fast growing trees planted simultaneously with crop; second, association with secondary forest thinned out to 50% of canopy to allow plantain crop to grow well with incident sunlight; and third, association with old forests which require trimming. Advantages of intermingling plantains with forest were evident at harvest. Plantain plants had good canopies, taller and thicker pseudostem and heavier and healthier bunches. Forest offers to plantains a good level of nutrients, better hydraulic conductivity which improves nutrition and reduction of fertilizer requirements. Main antagonist effect was competency for light, physical damages and longer vegetative cycles of plantain plants. Association offers until 45% of reduced cost of production and a novel methodology for farmers.

Jeff Daniells (Australia) Fusarium Wilt of Banana – An Integrated Approach to Disease Management (pp 50-55)

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Opinion Paper: “The only satisfactory long-term answer is the growing of resistant varieties” is often touted as the solution to Fusarium wilt. Unfortunately such a mind-set can lead to insufficient emphasis on biosecurity and other aspects of a holistic approach to disease management. Often farmers and scientists are living in false hope of what resistant varieties might offer them in the future. There are still many regions of the banana growing world that are free of Fusarium wilt as well as many locations that are free within those regions that are affected. More stringent quarantine, awareness programs and clean planting material schemes are needed urgently, particularly in parts of Asia and Oceania to prevent and/or minimize further spread of the pathogen. Studies have been underway for sometime now on the use of antagonistic microorganisms but greater understanding is needed of the optimum soil environmental conditions necessary for rapidly proliferating and maintaining their numbers in the field. The idea that these microbes need to be specially fed is often not well appreciated. Further studies are also necessary of the impact of GA on resistance and of natural plant resistance activators. There is also a need to clarify issues of disease resistance and tolerance from an horticultural point-of-view. Disease screening trials in north Queensland have indicated that moderately susceptible varieties such as Lady Finger (AAB, Pome) may be commercially productive in infested soils provided appropriate crop management measures are in place. More extensive screening of hybrids from breeding programs is required to enhance both the identification and utilization of hybrids with resistance to Fusarium.

Nzawele Benjamin Dowiya (Democratic Republic of Congo), Guy Blomme (Uganda), Djailo Benoit Dheda (Democratic Republic of Congo), Cornel Rweyemamu (Tanzania), Devrig Velly, Ndungo Vigheri, Augustin Milambo (Democratic Republic of Congo), Simon Eden-Green (UK), Eldad Karamura (Uganda), Amon Maerere (Tanzania) The Alarming Spread of Banana Xanthomonas Wilt in Eastern Democratic Republic of Congo and its Impact on Food Security and Income (pp 56-59)

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Original Research Paper: Xanthomonas wilt of banana (caused by Xanthomonas campestris pv. musacearum) is an unforgiving disease. Rather than merely reducing yield, as do many diseases, it causes the fruit to ripen prematurely and rot. Since 2001, the disease has spread to several countries in east and central Africa. It was first observed in the territory of Masisi, 72 km northwest from Goma in North Kivu Province, DR-Congo in 2001. During a survey conducted in May 2006 in the framework of the USAID-funded Crop Crisis Control Project (C3P), Xanthomonas wilt was also observed in the Mahagi and Irumu territories, Oriental province (north-eastern DR-Congo close to the border with Uganda) and in the region between Beni (north Kivu, DR-Congo) and Bundibugyo (western Uganda). Here the disease had most likely spread from infected areas across the border in Uganda. It had also spread over an area with a 50 km radius in Kitchanga, Masisi, North Kivu. A survey conducted in May 2008 in the framework of the Belgian-funded project CIALCA, reported that Xanthomonas wilt had entered South Kivu (Minova, Kalehe territory). In north Kivu the disease is currently present in the districts of Masisi, Rutshuru, Beni, Nyiragongo and Walikale and in Oriental province the disease is currently present in the Mahagi and Irumu districts. The disease has thus spread over an area more than 600 km long (north-south axis). At least two million people in eastern DR-Congo are impacted by this disease which threatens food security and farm income. The most important means of dissemination are infected planting materials, contaminated farm tools and insect vector transmission. Extension efforts to contain the spread of Xanthomonas wilt are hampered by insecurity and inaccessibility of large parts of eastern DR-Congo.

Meki Shehabu, Temesgen Addis (Ethiopia), Laban Frank Turyagyenda (Uganda), Tamiru Alemu, Shiferaw Mekonen (Ethiopia), Guy Blomme (Uganda) The Efficiency of Air-Drying Pared Corms of Banana Suckers in Reducing the Risk of Soil-Mediated Xanthomonas Wilt Infections in Ethiopia (pp 60-62)

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Short Communication: Xanthomonas wilt caused by Xanthomonas campestris pv. musacearum is one of the most threatening constraints to banana and enset (Ensete ventricosum) production in Ethiopia. The disease was unknown outside of Ethiopia until it was reported in Uganda in 2001. Since then the disease has spread to many East and Central African countries. Xanthomonas campestris pv. musacearum can only enter a plant through mechanical wounds (e.g. inflicted by garden tools) or natural wounds (e.g. male flower scars). Corm paring is a good practice for the control of weevils and nematode pests in banana but when the practice is conducted and corms planted in Xanthomonas wilt infected fields, Xcm infection occurs. As a solution, curing of corms before planting has been recommended. It is however not known if the recommendation could be adopted in Ethiopia. The study was therefore initiated to evaluate the efficiency of air-drying pared corms of banana suckers in reducing the risk of soil-mediated Xanthomonas Wilt infections under conditions prevailing in Ethiopia. Four treatments, i.e., pared and immediately planted, non-pared and immediately planted, pared and air-dried for three days and non-pared and air-dried for three days were tested for ‘Pisang Awak’ and a ‘Matooke’ genotype in a pot experiment. A total of 30 plants were used for each of the treatments per genotype. The disease incidence was recorded during six months after planting. Samples from dead or wilted plants were collected and plated on a YPSA medium at 28°C to confirm whether the disease symptoms were due to Xanthomonas campestris pv. musacearum. Paring and air-drying of banana suckers before planting increased soil-mediated Xanthomonas wilt infections. To reduce soil-mediated Xanthomonas infections, suckers should be carefully uprooted to avoid wounding and the uprooted suckers should be planted immediately after uprooting.

Meki Shehabu, Temesgen Addis, Shiferaw Mekonen (Ethiopia), Dirk De Waele (Belgium), Guy Blomme (Uganda) Nematode Infection Predisposes Banana to Soil-borne Xanthomonas campestris pv musacearum Transmission (pp 63-64)

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Short Communication: Xanthomonas wilt is the major disease affecting banana (Musa sp.) and enset (Ensete ventricosum) production in Ethiopia. A pot trial was carried out to establish the possible role of nematodes in soil-borne transmission of Xanthomonas campestris pv musacearum. Clean potted ‘Pisang Awak’ and ‘Matooke’ plants were first inoculated with a mixed population of nematodes [Pratylenchus goodeyi, Meloidogyne spp., Rotylenchus spp. and Radopholus similis] to allow for root damage. After three months, the surrounding soil was drenched with a suspension of Xcm (approximately × 10⁸ cells per mL) and plants were monitored for Xanthomonas wilt development. A significant disease incidence was observed in plants that had been previously infected with nematodes when compared to those which had not been infected with nematodes. It was concluded that the root damage caused by nematodes creates wounds that act as entry avenues for Xcm from the surrounding soil. It was recommended that these results be evaluated on-farm, but in the meantime, an IPM strategy should be adopted for control of Xanthomonas wilt in bananas and enset.

Sreeramanan Subramaniam, Maziah Mahmood, Sariah Meon, Xavier Rathinam (Malaysia) Genetic Engineering for Tolerance to Fusarium Wilt Race 1 in Musa sapientum cv. Rastali (AAB) Using Biolistic Gun Transformation System (pp 65-75)

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Research Paper: An effective method has been developed for the stable transformation and regeneration of silk banana cultivar ‘Rastali’ (Musa spp. AAB group) using biolistic gun method for tolerance to Fusarium wilt race 1 disease. Recent progress with advanced in vitro cultures of banana such as establishment of highly regenerable tiny single meristem buds opened the opportunity for the production of disease tolerant transgenic bananas. Chitinase and β-1,3-glucanase are important disease tolerance genes that were successfully transformed into banana together with gfp and gusA genes as reporter genes. Proliferating single buds were selected on geneticin G-418 to produce a number of putatively transformed bananas. Five different treatments using different chitinase and β-1,3-glucanase genes inserted singly or in combination were carried out. Molecular analyses such as polymerase chain reactions (PCR) and Southern blot were performed to confirm the integration and expression of the introduced genes into banana genome. The transgenic banana plantlets from each treatment were inoculated with 2 × 10⁶ spores per ml conidial suspension of Fusarium oxysporum f.sp. (Race1) to evaluate the degree of tolerance to fungal infections. Evaluation of disease development in primarily and secondary infections showed that combination of the two transgenes gave substantially greater protection against the fungal than single-transgene introduction. Productive interactions between chitinase and β-1,3-glucanase transgenes in planta point to combinatorial expression of antifungal genes as an effective approach to enhanced tolerance to Fusarium wilt disease in banana through genetic engineering.

Raman Thangavelu, Mohammed Mustaffa (India) A Potential Isolate of Trichoderma viride NRCB1 and its Mass Production for the Effective Management of Fusarium Wilt Disease in Banana (pp 76-84)

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Original Research Paper: Thirty-one isolates of Trichoderma viride, out of 110 isolates of Trichoderma spp. isolated from the rhizosphere of banana were effective in the initial screening tests conducted in vitro against banana wilt pathogen Fusarium oxysporum f.sp. cubense (Foc). These 31 isolates of Trichoderma viride and 6 isolates of other species of Trichoderma viz., T. viride-6, T. harzianum, T. koningii, T. pseudokoningii and T. hamatum, were subjected to intensive in vitro screening by dual culture and spore germination assay. Among these, T. viride isolate NRCB1 resulted in the maximum reduction in mycelial growth and spore germination. Different organic substrates were tested with two jaggery concentrations (1 and 5%) to mass-produce this isolate. The results showed that the fastest coverage of the entire substrate (5 days) as well as high population density (6 × 10³¹ CFU/g of material) occurred in rice chaffy grains added with 5% jaggery solution, compared to other substrates. Studies on shelf life indicated that population density of T. viride NRCB1 was significantly higher in rice chaffy grains formulation at both storage temperature (37 and 25°C), even after 5 months compared to other substrates and talc powder formulation. The pot culture and field studies indicated that the soil application of T. viride NRCB1 as chaffy grain formulation significantly reduced the Fusarium wilt disease of banana (up to 80%) and increased the plant growth parameters as compared to the talc powder formulation. The analyses of induction of PO and PAL and total phenolic content both in T. viride applied and Foc challenge inoculated plants revealed that these were significantly higher compared to control plants and plants inoculated with the pathogen (Foc)plants alone.

Catur Hermanto (Indonesia), Oscar S. Opina, Marina P. Natural (The Philippines) Assessment of Fungicide Resistance of a Population of Mycosphaerella Spp. on Señorita Banana Variety (Sucrier Group) (pp 85-90)

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Original Research Paper: Mycosphaerella leaf spot diseases have threatened world banana production. Yield losses from 40-50% have been reported in some cases. During the second cropping cycle, plantain yield loss due to black Sigatoka could reach 76%, and 100% loss of exportable fruits. In commercial banana plantations, fungicide has still become the main tool in mitigating development and effect of the disease; however, the dependence of fungicide for the control of banana diseases has led to a new problem of fungicide resistance. This research was to study the fitness and to assess fungicide resistance of Mycosphaerella pathogens causing banana leaf spot diseases from exposure of different fungicide pressures. The treatments were established based on a management scheme of fungicide resistance as follows: a) consecutive application of protectant (Mancozeb) fungicide; b) consecutive application of systemic (azoxystrobin) fungicide; c) alternate application of protectant and systemic fungicides; d) mixture application of protectant and systemic fungicides; e) control (i.e., no fungicide application). Fungicide treatments significantly reduced conidial density and its germination, and affected youngest leaf spotted (YLS) and the severity of Mycosphaerella leaf spot diseases. Consecutive azoxystrobin applications consistently resulted in the lowest conidial densities that were significantly different from consecutive applications of mancozeb, and the unsprayed control. The lowest conidial germination resulted by application of azoxystrobin but it was not significantly different from the other fungicide treatments. The fungicide application, however, significantly differed from the untreated control. Ten consecutive applications of azoxystrobin resulted in a 5.1-fold pathogen resistance as compared with control. Development of azoxystrobin resistance was also observed in a mixed application of azoxystrobin and mancozeb, consecutive application of mancozeb, and alternate application of azoxystrobin and mancozeb.

Eyob Tadesse, Ferdu Azerefegne, Tameru Alemu, Temesgen Addis (Ethiopia), Guy Blomme (Uganda) Studies on the Efficacy of Some Selected Botanicals against Enset Root Mealybug (Cataenococcus ensete) Williams and Matile-Fererro (Homptera: Pseudococcidae) (pp 91-94)

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Original Research Paper: Different botanicals were tested for their effect on Enset root mealybugs’ mortality in the laboratory and in pot experiments. Seed-water suspension of 10% Millettia ferruginea was toxic to Enset root mealybugs. The dose-response bioassay of M. ferruginea was calculated to be LD₅₀ = 40.39 mg/5 cm³ of soil. With the pot experiment, drenching the soil on which the infested young Enset plants were planted with seed water suspensions of 10% M. ferruginea caused a higher level of mortality (66%) compared to the other botanicals and the untreated plants. On the other hand, two times applications of M. ferruginea improved its efficacy from 66% to 79%. However, M. ferruginea was inferior to the synthetic insecticide Diazinon 60% EC in the pot and dipping experiments.Drenching seed-water suspension of 10% M. ferruginea in to the root zone of infested Enset plants in the field was found to be effective against the Enset root mealybugs. Millettia trees are abundantly found in the area and seeds can be collected and stored for long time. The preparation is simple and requires less technical skills. Thus, combinations of dipping young Enset seedlings in Millettia solutions and drenching of the solutions to the root zone of infested Enset plants can be used for the management of Enset root mealybugs.

Eyob Tadesse, Ferdu Azerefegne, Tameru Alemu (Ethiopia), Guy Blomme (Uganda), Temesgen Addis (Ethiopia) The Effect of Insecticides against the Root Mealybug (Cataenococcus ensete) of Ensete ventricosum in Southern Ethiopia (pp 95-97)

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Short Communication: The effect of six commercially available insecticides was evaluated for the control of the enset root mealybug, Cataenococcus ensete (Williams and Matile-Ferrero) (Hemoptera: Pseudococcidae) under greenhouse and farmers’ field conditions. In the greenhouse study, pared and boiled water treated seedlings of E. ventricosum were planted in 10-liter pots and infested at 2 months after planting with 25 third-instar C. ensete per plant. Each insecticide was diluted to a 1/500 concentration and applied at a rate of 660 ml of diluted solution per pot. In the farmers’ field study, the number of adult C. ensete before insecticide application was estimated by sampling a 20 × 20 × 20 cm soil volume at one side of the plant. Each plant was drenched with 1.7 liters of diluted insecticide solution. The results showed a significant difference (p<0.05) in C. ensete mortality amongst the treatments. Diazinon 60% EC and Chlorpyrifos 48% EC caused at least 98% mortality both under field and greenhouse conditions. Applications of Endosulfan, Dimethoate, Fenitrothion and Malathion resulted in a 74, 65, 77 and 83% mortality in the greenhouse experiment and a 51, 65, 51 and 50% mortality in the field trials, respectively. The efficacy of a double application of Malathion, Fenitrothion, Endosulfan and Dimetohate was inferior to a single application of either Chlorpyrifos or Diazinon. Therefore a single application of Diazinion or Chlorpyrifos is recommended. However, it is advisable/imperative that farmers continuously monitor infestation levels in their enset plots by assessing adult root mealybug numbers in soil samples dug out adjacent to the corms and repeat insecticide applications when a mealybug population build up is observed.

Masamba Jean Walangululu, Murhonyi Rodrigue Matara, Lukangira Bahati (Rwanda), Célestin Niyongere (Burundi), Pascale Lepoint, Guy Blomme (Uganda) Assessing the Spread and Seasonal Influence of Fruit Peel Disease and Banana Bunchy Top Disease in South Kivu, Eastern DR-Congo (pp 98-104)

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ABSTRACT

Original Research Paper: Baseline studies and subsequent diagnostic surveys carried out in south Kivu, DR-Congo by the Consortium for improving agriculture-based livelihoods in Central Africa (CIALCA) revealed that banana is severely affected by several diseases in the region, especially in Nyangezi and Kamanyola. Two major diseases are observed on the crop; banana bunchy top disease (BBTD) and a fruit peel disease of unknown origin. Studies of the two diseases were carried out by the Université Catholique de Bukavu in order to assess disease spread and seasonal influence. Survey results indicate that both diseases are well known by farmers and BBTD is more prominent at lower elevations (<1,300 masl), while the fruit peel disease is only present at higher elevations (>1,700 masl). The fruit peel disease (locally named ‘Cibojo’) has been reported in the region for over 50 years and infections mainly appear in fields were the disease has been observed previously. The symptoms start off as tiny reddish-brown specks on the fruit peel which enlarge to become irregularly shaped reddish-brown lesions. These lesions can eventually cover the whole fruit peel, leading to the splitting of the fruit in the terminal stage of the disease and rendering bunches unsuitable for human and animal consumption. An increase in severity of symptoms is observed during the rainy season (especially during weeks of heavy rains) whereas symptoms are limited to small blemishes on the peel during the dry season, unaffecting fruit pulp. The causal agent still awaits formal identification. In the Kamanyola area (1,000 masl) banana is severely affected by BBTD. The disease has been present in this region for over 20 years and although all varieties are susceptible, the beer banana ‘Nakasimbu’ or ‘Yangambi Km5’ (Musa AAA group) is most affected, while ‘Gros Michel’ (Musa AAA group) is least affected.