Thirty isolates of fluorescent pseudomonads were obtained from rhizosphere of different crops in Raichur, India. The fluorescent pseudomonad strains were characterized in vitro for biochemical traits, antimicrobial traits, and pyoluteorin antibiotic production. All the isolates that showed fluorescent pigment production under UV light were rod shaped, Gram negative, positive for oxidase, catalase and citrate utilization tests, and negative for indole test. Out of 30 isolates, 07 isolates were positive for HCN production, 15 isolates were positive for H2S production, and all the isolates were positive for siderophore production. Among all the isolates, RFP-22 showed the maximum percent inhibition of mycelium (46.66 %) of Rhizoctonia solani, the pathogen, and the remaining isolates showed the moderate to least inhibition of mycelium growth of R. solani. The 16S rRNA analysis confirmed that the antibiotic positive isolates belonged to genus Pseudomonas. The amplification of 779 bp region in isolates RFP- 4 and RFP-19 corresponded to pyoluteorin antibiotic-coding pltB gene. Further characterization of pyoluteorin antibiotic through TLC and TOF–MS analysis confirmed the presence of pyoluteorin at 274.26 (g/mol) peak and 2.10 min retention time. Biochemical and molecular analyses confirmed the antagonism of Pseudomonas and isolate through pyoluteorin production.

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Plant pathogenic fungi and bacteria are a significant threat to global commercial crop production resulting in increased cost of production, reduced crop establishment and productivity. An effort was made to study the antimicrobial activity of silver hydrogen peroxide (SHP) against selected plant pathogenic fungi and bacteria under in vitro conditions. Higher antibacterial activity of SHP was observed against Xanthomonas axonopodis pv. citri (Xac; 39.67 mm), Xanthomonas citri pv. punicae (Xap; 39.00 mm), and Ralstonia solanacearum (Rs; 36.67 mm) at 500 ppm concentration. SHP was superior to streptocycline (500 ppm) against Xac (25.33 mm) and Xcp (22.67 mm) at 100 ppm. The soil-borne fungi viz., Pythium aphanidermatum and Fusarium solani failed to initiate mycelium growth on PDA at the concentration of 5000 ppm and above. The average size of SHP particles was 462 nm in diameter, and 73.40% of particles had the size of 378 nm, which reflects the particles present in SHP solution in the form of colloids. The effective doses (100–5000 ppm) did not show any phytotoxicity symptoms in plants, while leaf necrosis was noticed at 10,000 ppm after four days of application. SHP (≤5000 ppm) can be used to effectively manage both fungal and bacterial plant pathogens by a single application. Further field studies need to be conducted for validation and commercial use of SHP.

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