Banana Xanthomonas wilt in Ethiopia: Occurrence and insect vector transmission

Bacterial wilt caused by Xanthomonas vasicola pv. musacearum (Xvm) is an important disease of enset and banana in south and south-western Ethiopia where, the diversity of the insect fauna on banana inflorescences was unknown and the role of insects as vectors of the disease had not been studied. The objectives of this study wereto assess the occurrence of bacterial wilt and male bud infection, the diversity of insect families in banana plantations and the presence of the bacteria on insects collected from diseased inflorescences in south and southwestern Ethiopia. Surveys were carried out and insects were collected from three different zones in 2005. The diversity and richness of the insect families was assessed across sites and genotypes and comparisons were made using the Shannon Diversity Index and the Jack knife estimator, respectively. Correlations were made betweenthe abundance and incidence of insects with the incidence of male bud infection on ‘Pisang Awak’ plants. A wide range of insect families were recorded and they varied according to banana genotype and altitude. The Drosophilidae and Apinae families were most frequently recorded across sites and genotypes. The ‘Wendo’ variety (AAACavendish group) had the highest diversity and richness of insect families within and across sites. In contrast to the Kembata Tembaro and Bench Maji zones, severe and widespread male bud infection of banana was found in Kaffa, where there was a high diversity of insects on the ‘Pisang Awak’ and ‘Abesha muz’ plants. The incidenceof male bud infection on ‘Pisang Awak’ plants was highly correlated with the incidence of insects (R2 = 0.964). The incidence of male bud infection however depends on the floral morphology and altitude. Artificial inoculation with Xvm ooze on fresh male bract and flower scars resulted in infections on ‘Pisang Awak’ and ‘Abesha muz’ plants, but the ‘Dwarf Cavendish’ plants with persistent bracts and flowers remained healthy. Few male bud infections were observed at altitudes above 1,700 masl. Xvm was isolated from Apinae, Lonchaeidae, Muscidae,Tephritidae and Vespidae insect families. Lonchaeidae (Silba spp.) were frequently observed on banana bract and flower scars and could thus be an important insect vector of Xvm in Ethiopia

Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions

Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discolorationof the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of thedisease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet,it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removalof the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonaswilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in somebanana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread

Root and shoot development during the plant crop and the first ratoon of banana and plantain (Musa spp.) with implications for perennial cultivation on degraded Ultisols in southeastern Nigeria

The effect of cycle on root system and shoot development was studied for two crop cycles (plant crop and first ratoon). The study revealed that shoot and root system development declined from the plant crop to the first ratoon for plants grown on degraded Ultisols in south-eastern Nigeria.El efecto cíclico en el sistema radical y en el desarrollo de otras partes de la planta fue estudiado durante dos ciclos de producción (siembra y primer renuevo). El estudio reveló que el desarrollo del sistema radical y otras partes de la planta declinó desde el momento de la siembra hasta el primer renuevo en plantas sembradas en Ultisoles degradados en el sureste de Nigeria

Relationship between root and shoot growth traits during the plant crop and first ratoon in banana and plantain (Musa spp.) and its implications for perennial cultivation on degraded Ultisols in southeastern Nigeria.

The effect of cycle on root system and shoot development was studied for two crop cycles (plant crop and first ratoon). The study revealed that shoot and root system development declined from the plant crop to the first ratoon for plants grown on degraded Ultisols in south-eastern Nigeria

Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions

Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discoloration of the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of the disease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet, it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removal of the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonas wilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in some banana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread