Evaluation of pathogenic isolates in Ethiopia for the control of chocolate spot in Faba bean

Abstract

Faba bean (Vicia faba L.) is one of the earliest domesticated food legumes in Ethiopia and is now cultivated on large areas in many countries. Production of the crop is, however, constrained by several disease infections including fungal diseases. The objectives of this work was to find out natural prevalence of Bacillus isolates on faba bean leaves in Amhara Regional state of Ethiopia; and to identify potential biocontrol agents for the management of chocolate spot (Botrytis fabae). Thirty eight distinct groups of isolates of Bacillus species out of a total 110 isolates obtained from 12 districts of north-west Ethiopia were found to occur on faba bean leaves. They differed in morphological and cultural characteristics. Thirty isolates of Bacillus spp. were tested for their effects on Botrytis fabae pathogen by dual culture technique on potato dextrose agar. Sixteen isolates produced 5 mm or higher inhibition zone and out of these isolate 43y and 56y were the most effective having inhibition zone of 8 and 7 mm, respectively. Isolates reduced the growth of the pathogen colony in dual culture by 23-64%. The highest reduction was caused by isolate 115y (64%), followed by 114-3y (52%) and 29y and 67y (50% each). Isolates of Bacillus were placed on actively growing colonies of B. fabae and were found to cause lysis of B. fabae mycelium. Eleven isolates caused 8 mm or higher lytic area of mycelium. Maximum lysis of mycelium was caused by isolates 111-1y (16.8 mm) and 116y (11.3 mm), and they were confirmed from CABI Global Plant Clinic as Bacillus and not pathogenic to plants and animals. Further evaluation of promising antagonistic isolates by the detached leaf technique showed that most of them reduced the disease development on leaves. However, the degree of disease reduction varied with cultivar. Isolates 108-2y, 20-2y, 47-2y and 36-1y proved most effective in retarding disease development on two susceptible and one tolerant cultivar and can be further explored for commercial use for management of chocolate spot disease of faba bean.Key Words: Bacillus spp., Biocontrol, Botrytis fabae, Ethiopia RÉSUMÉLe haricot faba (Vicia faba L.) est l'un des premiers domestiqués légumineuses alimentaires en Ethiopie et en est maintenant cultivé sur de grandes superficies dans de nombreux pays. La production de plant est toutefois limitée par des infections de plusieurs maladies don't les maladies fongiques. Les objectifs de ce travail étaient de découvrir la prévalence naturelle des isolats de Bacillus sur des feuilles de haricot faba dans la régions d'Amhara en Éthiopie; et d'identifier d'éventuels agentd de lutte biologique pour la gestion de taches chocolats (Botrytis fabae). Trente huit groupes distincts d'isolats d'espèces de Bacillus sur un total de 110 isolats obtenus à partir de 12 districts du Nord-Ouest de l'Éthiopie avaient été trouvés présents sur des feuilles de haricot faba. Ils différaient par les caractéristiques morphologiques et culturales. Trente isolats de Bacillus spp. avaient été testés pour leurs ...

<i>In Vitro</i> Antagonistic Activity of <i>Trichoderma harzianum</i> and <i>Bacillus amyloliquefaciens</i> against <i>Colletotrichum acutatum</i>

“…Similar results have been reported by [19]. [20] reported that Bacillus were promising bacterial antagonists for the control of plant diseases, because of their simple nutritional requirements, which allow them to colonize on dry surfaces for long periods of time, the rapid use of many available nutrients and endospores resistant to withstand many environmental risks. Bacillus species, in-cluding B. amyloliquefaciens [21] [22] [23], significantly reduce the severity of plant pathologies on various hosts under greenhouse or field conditions [24].…”

On-Farm Demonstration of Improved Varieties of Faba bean (Vicia fabaL.) in Gemechis, Chiro and Tullo Districts of West Hararghe Zone, Oromia National Regional State of Ethiopia

“…Faba bean is a valuable protein-rich food that provides a large sector of the human populations in developing countries with a cheap protein source thus partly compensating for the large deficiency in animal protein sources. It is one of the earliest domesticated food legumes and is now cultivated on large areas in many countries due to its high nutritive value in terms of energy and protein contents (24-30%) (Sahile et al, 2009).…”

Characterization of faba bean (Vicia faba L.) rhizosphere associating rhizobacteria against Botrytis fabae AAUBF-12 and their plant growth-promoting properties

“…Bacillus spp. also displayed 23-64 % mycelial growth inhibition of B. fabae under in vitro conditions (Sahile et al, 2009), Ahmed (2015) and El-Banoby et al (2013) have reported the inhibitory activity of B. subtilis on the mycelial growth of B. fabae by 62.6 % and 67.03 % respectively. Similarly, de Senna and Lathrop (2017) showed that Serratia plymuthica inhibited the growth of Botrytis cinerea by 51 % under in vitro study.…”

“…The hitherto studies focused on screening of selected isolates such as Bacillus and Pseudomonas spp. antagonistic to B. fabae under laboratory conditions in Ethiopia (Sahile et al, 2009;Alemu, 2016). However, there is a dearth of information on the genetic identification and plant growth-promoting properties of rhizobacteria isolated from the rhizosphere of faba bean.…”