Bio-management of soil borne pathogens infesting cucumber (Cucumis sativus L.) under protected cultivation system

Trichoderma harzianum, Bacillus subtilis and Pseudomonas fluorescens were tested separately and together under in vivo for their ability to supress soil borne pathogens i.e. Meloidogyne incognita, Fusarium oxysporum and Rhizoctonia solani infesting cucumber (Cucumis sativus L.) cv. Magicstar in two consecutive trials (2018-2020) under protected cultivation system. The initial mean population of M. incognita, F. oxysporum and R. solani was recoded 1.72 J2/g soil, 1.3 x 10(3) cfu/g soil and 7.8 propagules/50 cc soil respectively. Freshly prepared bio-agents were used as soil and drench application. Tested bio-agents were mixed with FYM and vermicompost for fortification before soil application, whereas for drench application, they were mixed with water at the rate of 5 ml/l. The suppressive effect of bio-agents was significantly (P > 0.05) greatest with combined bio-agents (T. harzianum + B. subtilis + P. fluorescens) application treatment which caused greatest reduction of M. incognita, F. oxysporum and R. solani multiplication which was up to 90% at the end of subsequent second season trial with significant enhancement in plant health. The eggs of M. incognita obtained from plants treated with all tested bio-agents showed least hatching (20%) when subjected to bioassay test after termination of experiments. Fluensulfone did not affect multiplication of F. oxysporum and R. solani in soil but establish the reduction in shoot and root disease severity in the plant system. Tested bio-agents were successfully established in the rhizosphere of cucumber plants which showed compatibility among them, hence may be ideal companions to develop consortia against soil borne diseases under protected cultivation system.

Automated summary

The combination of Trichoderma harzianum, Bacillus subtilis, and Pseudomonas fluorescens showed significant suppressive effects on soil borne pathogens infecting cucumber plants under protected cultivation system. These bio-agents also successfully established in the rhizosphere of cucumber plants and showed compatibility among them, indicating their potential as ideal companions to combat soil borne diseases in protected cultivation systems.