Biological control of Pseudomonas syringae pv. garcae in coffee crop with Bacillus spp. isolates

Abstract

Among the diseases that affect the coffee crop, bacterial blight caused by Pseudomonas syringae pv. garcae (Psg) stands out due to production losses. This study evaluates the antagonistic effect of Bacillus spp. against Psg both in vitro and in coffee seedlings. In vitro antagonism was evaluated by the double layer method for the inhibition of Psg growth. Subsequently, in vitro selected antagonists were tested for their ability to inhibit bacteriosis in coffee seedlings (cv. Mundo Novo) under greenhouse conditions. It was evaluated nonspecific met­abolic production by antagonistic bacteria and identified the isolates that stood out in the in vitro experiment. Iso­lates considered as the most promising in vitro experiments (23% of the total) were chosen for the antagonistic efficiency test in a greenhouse. Isolates B04, B05, B22, B31, B53, B202, B208, B264, B266, and B294 showed ammonia production. Isolates B04, B33, and B294 showed hydrocyanic acid production. Isolates B04, B05, B18, B22, B33, B53, B105, B202, B208, B264, and B294 showed siderophores production. In addition, isolates B18  (B. subtilis), B22 (B. thuringiensis serovar israelensis), B05 (B. methylotrophicus), B53 (B. safensis), B202          (B. subtilis), and B33 (B. subtilis) reduced more than 80% the severity of bacterial blight under greenhouse condi­tions. Field experiments should be conducted to confirm the potential of these isolates for bacterial blight man­agement.