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Olfactory cues guide plant parasitic nematodes (PPNs) to their host plants. We tested the hypothesis that non-host plant root volatiles repel PPNs. To achieve this, we compared the olfactory responses of infective juveniles (J2s) of the PPN

African Indigenous Vegetables (AIVs) are widely consumed in Kenya as part of everyday meals. They provide the much-needed micro-nutrients which are critical for combating micronutrient deficiencies (“hidden hunger”). The study describes the socio-economic characterizes of households in rural and peri-urban areas in Kenya and appraises the contribution of AIVs to household food access. The results show that there are spatial variations in the consumption of AIVs. Households living in rural areas have a wider variety of vegetables and consume their own production for an estimated ten months in a year; at the same time, purchase vegetables for between 6-7 months. Their peri-urban counterparts have less variety, consume their own produce for 11 months in the year and purchase for 8-9 months. Household income plays a critical role in enabling participation in food markets, Households living in rural areas earn significantly less on average from their land, their annual salary and net profits compared to their peri-urban colleagues. At least 40 per cent of households living in rural areas compared to an estimated 20 per cent in peri-urban areas grade their vegetables. In contrast, 50 per cent of all households wash their vegetables before consumption. In conclusion, households’ living in rural areas are net buyers of food, indicating that interventions to ensure increased consumption of AIVs must be accompanied by broad-based livelihood improvements to ensure that benefits accrue. Also, there is a need to underscore the importance of extension services as knowledge brokers.

Seedling damping-off disease caused by Pythium aphanidermatum is the most important seedling disease in tomato production in Kenya. The disease causes seedling losses of up to 30%. Greenhouse trials were conducted to evaluate the application of Bacillus subtilis and Trichoderma asperellum , as seed coating for management of damping-off in tomato from April 2011 to August 2014. Tomato seeds (var. Rio Grande) were coated with either B. subtilis or T. asperellum at a concentration of 10 6 CFU/ml. The interaction between the two biocontrol agents and NPK fertilizer was assessed. To simulate the effect of high disease pressure, the coated seeds were planted in P. aphanidermatum inoculated media. The post-emergence seedling damping-off on seeds coated with B. subtilis and T. asperellum was 20.19% and 24.07% respectively while the control (non-coated) had 65.89% seedling mortality. A combination of NPK fertilizer and biocontrols in seedling management resulted to a significantly higher dry mass compared to the use of either biocontrol agent or fertilizer alone ( P ⩽ 0.001). This study indicates that coating of tomato seeds with B. subtilis and T. asperellum may be useful in the management of damping-off disease.

The genetic variability of banana bunchy top virus (BBTV) isolates from the Great Lakes region of Africa (GLRA) spanning Burundi, the Democratic Republic of the Congo and Rwanda was assessed to better understand BBTV diversity and its epidemiology for improved disease management. DNA-R and DNA-S fragments of the virus genome were amplified and sequenced in this study. These two BBTV fragments were previously used to classify isolates into the South Pacific and the Asian groups. Phylogenetic analyses based on nucleotide sequences involving GLRA isolates and those obtained from the GenBank database were carried out. Sequence similarity for both DNA-R and DNA-S fragments ranged between 99.1 to 100.0% among the GLRA isolates, 96.2 to 100.0% and 89.7 to 94.3% between the GLRA isolates and those previously clustering in the South Pacific and the Asian groups, respectively. These results showed that GLRA isolates belong to the South Pacific group and are phylogenetically close to the reference Indian isolate. The similar banana cultivars and BBTV isolates across the GLRA implied that the disease may have mainly spread through exchange of planting material (suckers) between farmers. Thus, farmers’ awareness and quarantine measures should be implemented to reduce BBTV spread in the GLRA. Key words: Banana bunchy top disease (BBTD), Musa spp., Pentalonia nigronervosa, virus genome.

The root-lesion nematode Pratylenchus goodeyi is a common pest of banana in Kenya, which results in significant yield losses. An emerging option for the management of banana nematodes includes the use of endophytic fungi, which cause no damage to their hosts but often extend benefits, such as enhanced protection against various biotic and abiotic constraints. In the current study, non-pathogenic Fusarium oxysporum strains originating from banana (Musa spp.) in Kenya (4MOC321 and 11SR23) and Uganda (V5w2) were evaluated for their efficacy against P. goodeyi in tissue culture-derived plantlets (cv. Giant Cavendish and cv. Grand Nain) in pots. Pratylenchus goodeyi densities were 47-60% lower in endophyte-inoculated relative to non-inoculated plants and root necrosis damage was reduced by >30%. Endophyte treatment had no effect on plant growth parameters compared with untreated control plants. The performance of the two Kenyan strains was equally effective as the positive control (V5w2), thus demonstrating their potential as nematode bio-control agents under Kenyan growing conditions.

This study on the epidemiology of banana bunchy top disease (BBTD) was carried out in the context of small-scale farms in Burundi for an integrated management approach. Banana trials were established in farmers’ fields comparing different plot locations, while spatial and seasonal occurrence of aphid vectors was evaluated at three different altitudes. In addition, serological tests were performed on banana leaf samples to confirm the presence and titre of the virus. The results showed that BBTD incidence varied among banana cultivars and locations. Nine months after plot establishment, BBTD incidence ranged from 21·8% to 56·4% in plots within affected fields, while a range of 0–12·3% was reported in plots located between 5 and 30 m away from affected banana fields. Aphid numbers were highest in the dry season. These aphids were able to acquire and transmit the virus irrespective of altitude. A mean incubation period of 21 and 84 days was observed at low (780 m a.s.l.) and high (2090 m a.s.l.) altitude, respectively. Thus, a holistic approach, taking into account banana cultivar, plot location, disease-free planting material and regular field sanitation, should be promoted for long-term BBTD management.

The original publication is available at www.actahort.org. Banana bunchy top disease (BBTD), caused by the Banana bunchy top virus (BBTV), is reported as one of the most devastating diseases affecting banana and plantain cultivation worldwide. In order to identify putative sources of resistance, a cultivar screening trial comprising 40 Musa genotypes was established in March 2007 at the ISABU Mparambo research station in northwestern Burundi (893 m a.s.l.). Dessert bananas (AAA group), East African highland bananas (AAA, EAHB), plantains (AAB), cooking bananas (ABB), a tetraploid hybrid and wild diploid bananas (Musa acuminate and Musa balbisiana) were assessed. Ten plants per genotype were planted in a completely randomised design with border rows consisting of BBTV-infected 'Yangambi Km 5' (AAA) plants. Colonies of Pentalonia nigronervosa collected in BBTV-infected fields were released in the plot to enhance disease spread. Twenty-eight months after trial establishment, 32 genotypes have shown typical banana bunchy top symptoms. The first symptoms appeared 80 days after trial establishment on 'Yangambi Km 5'. Twenty-eight months after trial establishment, only eight genotypes [Musa balbisiana type Tani (BB), 'Kayinja' (ABB), 'FHIA-03' (AABB), 'Prata' (AAB), 'Gisandugu' (ABB), 'Pisang Awak' (ABB), 'Saba' (ABB) and 'Highgate' (AAA, Gros Michel subgroup)] have not manifested typical disease symptoms on any of the ten plants per genotype. Plant samples taken from these visibly healthy cultivars and analysed at a molecular level [at the Faculte Universitaire des Sciences Agronomiques de Gembloux (FUSAGx) in Belgium] indicated the presence of the virus in 'Pisang Awak', 'Saba' and 'Highgate'. These genotypes can be considered as BBTD tolerant. They could potentially act as a reservoir for the virus. Further diagnostic tests will be carried out on the five BBTV-free genotypes to confirm the extent of latent infections. Preliminary results indicate that genotypes with one or two B genomes tend to be more tolerant to BBTD.