Published in Frontiers in Plant Science, a review by Bioversity International and partners describes global distribution, symptoms, pathogenic diversity, epidemiology and the state of the art for sustainable management of the major bacterial diseases affecting banana and enset.
The production of banana and enset (a close relative of banana) is affected by a range of bacterial diseases that cause major losses worldwide. Until recently, bacterial diseases of bananas and enset had not received an equal amount of attention compared to other major threats to banana production such as the fungal diseases black leaf streak (Mycosphaerella fijiensis) or Fusarium wilt (Fusarium oxysporum f. sp. cubense). However, as it turns out, bacteria cause significant impacts on bananas globally and management practices are not always well known or adopted by small-scale farmers.
Bacterial diseases in bananas and enset can be divided into three groups: (1) Ralstonia-associated diseases (Moko/Bugtok disease caused by Ralstonia solanacearum and banana blood disease caused by R. syzygii subsp. celebesensis); (2) Xanthomonas wilt of banana and enset, caused by Xanthomonas campestris pv. musacearum and (3) bacterial head rot or tip-over disease caused by Pectobacterium carotovorum (formerly Erwinia carotovora) and bacterial rhizome and pseudostem wet rot (caused by Dickeya paradisiaca formerly E. chrysanthemi pv. paradisiaca).
A new review paper – authored by scientists from Bioversity International, EMBRAPA (Brazil), The Royal Museum for Central Africa (Belgium), The Institute of Plant Health Research (Cuba), The University of Reunion (France) and CIRAD (France) – describes global distribution, symptoms, pathogenic diversity, epidemiology and the state of the art for sustainable disease management of the major bacterial wilts currently affecting banana and enset. The review paper draws attention to similarities across the bacterial diseases in symptom expression and control/management options.
“This review will benefit the banana community worldwide as it puts, for the first time, most of the available information on bacterial wilts of banana in a single place. The paper also highlights the geographical distribution and symptoms of these diseases in a clear way, and may help the diagnostic process and even quarantine regulations for those countries where specific diseases are not yet present, as is the case of Xanthomonas wilt in Latin American and the Caribbean,” said Miguel Dita, a scientist at EMBRAPA and co-author of the paper.
Acceptable management and control of bacterial diseases in banana and enset is achievable by following strict, coordinated and integrated activities. A first critical step in plant disease management is diagnosis. Disease recognition in banana plants affected by bacteria is achieved by plant-by-plant inspection of the plantation at regular intervals.
In regions, villages or farms where bacterial diseases are not present, the first line of defense is to avoid introducing them. Use of clean planting material and good sanitation procedures need to be always coupled to quarantine methods.
Where a disease is already present, control options should focus on a systematic area-wide approach, with the adoption of a combination of activities such as limitation of access of animals, regular disinfection of farm tools, early removal of male flowers/buds and of diseased plants, to name a few.
These activities, when area-wide performed in a systematic way and based on epidemiological parameters, may guarantee sustainable control.
“However, the current situations in Africa (for Xanthomonas wilt), Latin America and the Caribbean (for Moko and Dickeya) suggest that more efforts are needed at different levels. Growers, technicians and extension workers should be trained on disease recognition, epidemiology and management practices, with the support of plant protection experts,” said Guy Blomme, Bioversity International scientist and lead author. In the current molecular era, an integration of sensitive and specific diagnostic tools together with transgenic approaches, conventional breeding and screening for escape cultivars may offer environmentally friendly and less labour-intensive options to control bacterial diseases.
“This paper will help extension officers and national plant protection organizations to improve quarantine regulations and disease diagnostics in national surveillance programs. The paper also provides information on best biosafety practices for medium and small-scale banana growers to prevent the entry of a disease on farm and prevent subsequent dispersal,” concluded co-author Luis Pérez Vicente from INISAV, Cuba.
This study was supported by grants from the Office de Développement de l’Economie Agricole des Départements d’Outre Mer (ODEADOM) as part of the Réseau d’Innovation et de Transfert Agricole (RITA), and contributes to the CGIAR Research Program on Roots, Tubers and Bananas, which is supported by CGIAR Fund Donors.
Photos from top to bottom:
1. Xanthomonas bacterial wilt of enset caused by X. campestris pv. musacearum. The photos depict leaf yellowing and wilting, and pockets of bacterial ooze in a leaf petiole. Credit: Bioversity International/G.Blomme.
2. Geographic distribution of Moko/Bugtok bacterial wilt (Ralstonia solanacearum), blood bacterial wilt (R. syzygii subsp. celebesensis) and Xanthomonas bacterial wilt (Xanthomonas campestris pv. musacearum). Presence or absence of a disease is presented at country level. Source: Blomme et al. 2017
3. Xanthomonas bacterial wilt of banana caused by X. campestris pv. musacearum. The photos depict leaf yellowing and wilting, exudation of bacterial ooze, premature fruit ripening and fruit discoloration. Credit: Bioversity International/G.Blomme.