The risk posed by Xanthomonas wilt disease of banana: Mapping of disease hotspots, fronts and vulnerable landscapes

Abstract

Banana production landscapes in the African Great Lakes Region (AGLR) have been under immense pressure from Xanthomonas wilt (XW) disease over the past two decades. XW, first reported on banana in central Uganda and eastern DR Congo in 2001, has since spread to the entire AGLR. XW is currently spreading westwards from hot spots in eastern DR Congo highlands, putting the plantain ( Musa AAB genome) belt of central and west Africa at risk. In-depth understanding of the key variables responsible for disease spread, current hotspots, and vulnerable landscapes is crucial for disease early warning and management. We mapped aggregated disease distribution and hotspots in the AGLR and identified vulnerable landscapes across African banana production zones. Available data on disease prevalence collected over 11 years was regressed against environmental and expert developed covariates to develop the AGLR XW hotspots map. For the Africa-wide risk map, precipitation, distance to hotspots, degree of trade in fresh banana products, production zone interconnectedness and banana genotype composition were used as covariates. In the AGLR, XW was mainly correlated to precipitation and disease/banana management. Altitude and temperature had unexpectedly low effects, possibly due to an overriding impact of tool-mediated spread which is part of the management covariate. In the AGLR, the eastern part of DR Congo was a large hotspot with highest vulnerability. Apart from endemic zones in the AGLR and Ethiopia, northern Mozambique was perceived as a moderate risk zone mainly due to the predominance of ‘Bluggoe’ ( Musa ABB type) which is highly susceptible to insect-vectored transmission. Presence of XW hotspots (e.g. eastern DR Congo) and vulnerable areas with low (e.g. north-western Tanzania) or no disease (e.g. Congo basin, western DR Congo and northern Mozambique) pressure suggest key areas where proactive measures e.g. quarantines and information sharing on XW diagnosis, epidemiology, and control could be beneficial.

Raw wastewater irrigation for urban agriculture in three African cities increases the abundance of transferable antibiotic resistance genes in soil, including those encoding extended spectrum β-lactamases (ESBLs)

“…Therefore, plants grown in irrigated fields are more exposed to bacterial infections affecting crop productivity. Outbreaks of Xanthomonas wilt disease of banana are frequently reported in the region (Ocimati et al 2019).…”

A contingent valuation analysis for assessing the market for genetically modified planting materials among banana producing households in Uganda

“…10,11 Recent studies, however, report yield losses resulting from BXW infections to be as high as 100% if not controlled. 8,[12][13][14] Meanwhile, economic losses of about US$2--8 billion have been reported over a decade as a result of the disease. 15 As a result, average annual production declined from 10.5MT in 2002 to as low as 4.3MT in.…”

Benefits from the adoption of genetically engineered innovations in the Ugandan banana and cassava sectors: An ex ante analysis

“…2 In recent years, both cassava and banana have been threatened by the emergence and spread of destructive diseases. Banana Xanthomonas wilt (BXW) is predicted to destroy up to 90 percent of Ugandan bananas if not controlled (Ocimati et al, 2019;Blomme et al, 2014). BXW also threatens millions of farmers in Uganda with longterm negative impacts that include the death of mother plants that would otherwise contribute to new plantules development.…”

“…While there is no chemical or biological agent that has demonstrated control effectiveness, there are limited control measures for managing both diseases (Geberewold 2019;Alicai et al 2007). Efforts to address BXW have focused on cultural and agronomic practices including eliminating infected plants, enforcing on-farm phytosanitary measures, use disease-free planting materials, and quarantine which can have a positive impact if implemented in a proper manner (Ocimati et al 2019). Cultural and agronomic efforts in bananas have had limited success as the disease often resurges as farmers become complacent in their implementation.…”