P. Lepoint

Musa germplasm diversity status across a wide range of agro-ecological zones in Rwanda, Burundi and Eastern Democratic republic of Congo.

Objectives: This study assessed the on-farm Musa germplasm diversity across different agro-ecologies of Rwanda and the socio-economic utilization options and selection practices that create/maintain this diversity on-farm. Methodology and results: A Musa germplasm diagnostic survey was carried out in 2007 in five Rwandan districts on a transect from Lake Kivu (West) to Kirehe district (East) bordering Tanzania. Across all sites, 118 farms, each having at least 50 mats were sampled for determining Musa diversity. Forty three Musa cultivars were recorded across the five districts. Higher diversity was observed in the east declining westwards to the Lake Kivu region as reflected by the number of cultivars and their relative abundance. Nearly half of the recorded cultivars had a low diversity index (Gini-Simpson 1-D < 0.2) and therefore prone to genetic erosion. Cooking cultivars only dominate in the district of Kirehe, while beer cultivars dominate the banana production landscape in the other districts. Taste/flavor, bunch size and market demand were the most important criteria for banana cultivar selection and thus greatly influenced cultivar conservation and distribution on-farm. Diseases such as Fusarium wilt and Xanthomonas wilt greatly contributed to genetic erosion. Conclusion and application of results: Musa cultivar diversity in Rwanda is under threat. Ex-situ conservation of the menaced cultivars is of crucial importance. Beer cultivars dominated the landscape. Cultivar diversity on-farm was influenced by the prevailing altitude; taste/flavor, bunch size, and market demand of the cultivars; and their susceptibility to diseases especially Fusarium and Xanthomonas wilt. Banana breeding or adaptation strategies therefore should take into account the farmer preferred traits. In addition, strategies for managing these diseases are critical for preventing the genetic erosion of the affected cultivars.

Assessing incidence, development and distribution of banana bunchy top disease across the main plantain and banana growing regions of the Democratic Republic of Congo

Banana bunchy top disease (BBTD) was first identified in DR Congo in 1958. Previously, the disease’s distribution throughout the Congo basin had not been studied, so an initial study, to determine the incidence and severity of BBTD in banana and plantain producing regions of Oriental province, was carried out during 2009 to 2010. Three hundred (300) farms were surveyed across 4 districts and 19 territories, with 30 mats assessed per farm. Visible disease symptoms were recorded and serological tests using triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) were carried out on collected samples. Additional surveys were conducted during 2010 to 2012 in Maniema, Northern Katanga, Eastern and Western Kasai, Bandundu and Equateur provinces to assess the distribution of the aphid vector (Pentalonia nigronervosa), BBTD incidence and severity. 92% of mats observed across Oriental province manifested BBTD symptoms but severity levels were low. All plantain and banana cultivars grown in farmers’ fields were susceptible to the disease. The vector, P. nigronervosa, was found on 89% of all assessed mats. In Tshopo district, all samples collected on plants showing disease severity scores 2, 4 and 5 tested positive for the presence of the virus. However, only 48% of plants with severity score 1 and 33% of plants with score 3 gave positive TAS-ELISA results. More importantly, 40% of symptomless plants (score 0) tested positive. The average BBTD incidences in Bandundu, Equateur, Eastern and Western Kasai, Katanga and Maniema were lower than levels observed in Oriental province. The lowest incidence levels were observed in Equateur (43%) and Katanga (35%). Although, BBTD is widespread in the surveyed provinces, the generally observed low severity levels result in limited impact on production. The generalized spread of BBTD in surveyed areas nevertheless underlines an urgent need to identify virus-free plants for multiplication and distribution of disease-free materials to small-scale farmers.

Cultural Practices for Banana Bunchy Top Disease Management: a Sustainable Option for Burundian Smallholders?

Banana bunchy top disease (BBTD) was reported for the first time in Burundi in 1987. Ever since, the disease has continued its spread throughout the Rusizi valley, reaching ever-higher altitudes, as no specific measures are being taken for its control. Management of BBTD through symptom and vector identification and good cultural practices was evaluated during a 1-year period in an on-farm, research-led trial at Munyika (Cibitoke Province) in a predominant monocrop system of ‘Yangambi Km 5’ (AAA). In addition, a “new start” demonstration trial consisting of in vitro ‘FHIA-03’ (AAAB), ‘FHIA-17’ (AAAA) and ‘FHIA-23’ (AAAA) plantlets was established 80 m away from existing plantations. In parallel, two contrasting control sites (no awareness raising and no cultural practices) within Cibitoke were identified (Mparambo II, ‘Yangambi Km 5’ monocrop and Muyange, ‘Igitsiri’/’Igisahira’ (AAA-EA) intercrop). BBTD incidence and severity were recorded quarterly in all three sites. Results indicate that initial BBTD incidence varied from one site to another, with lower incidence in ‘Igitsiri’/’Igisahira’ intercropping systems (8.6%) compared to ‘Yangambi Km 5’ monocropping systems (30.9%). Furthermore, in the pilot village Munyika, disease incidence was higher in the vicinity of households (26.2%) versus in recent plantations (2.7%). Data collected in Munyika show that when appropriate cultural practices are applied and adhered to, within a year, BBTD incidence can be reduced to economically acceptable levels in an existing plantation (26.2% to 8.2%) and in new plantations (2%, FHIA trial). Moreover, severity is equally reduced, highlighting that farmers are presently familiar with initial symptoms and regularly scout fields to eradicate diseased plants. However, low adherence to proposed management practices underlines that most farmers – despite awareness raising are reluctant to uproot the entire mat (100% of farmers) or the diseased corm (78% of farmers) when a single plant manifests visible symptoms. Refusal to conform to proposed practices might prove to be a limiting factor to sustainable management of BBTD in Burund