Vol. 11, Issue 7 (2022)

Author(s):
Swati Gautam, Anjali Chauhan and CK Shirkot

Abstract:
Bacterial canker is the most contagious and destructive disease of tomato caused by Clavibacter michiganensis ssp. michiganensis (Cmm) can drastically reduce tomato yield and quality, thus causing substantial economic losses both in greenhouses and in open-field production. The pathogen is seed borne, persists in plant debris in soil and on contaminated greenhouse structures and infected seeds. It infects host plants via roots or wounds and invade the xylem vessels, followed by a systemic infection of the host which results in leaf lesions, wilting, fruit lesions and ultimately yield loss of marketable fruits. Biological control through the use of beneficial microorganisms or by the combination of multiple antagonists colonizing on the rhizosphere, surface and inner tissues of healthy plants has emerged as a promising alternative to chemical pesticides as a more rational and safer crop management over disease control. A total of 550 rhizobacterial isolates from different horticultural, vegetable crops and medicinal plants grown under mid hills and high hills of Himachal Pradesh were screened for antagonistic activity against Clavibacter michiganensis. Out of total, only 40 bacterial isolates showed antagonistic activity by depicting inhibition zone in the range of 3.20 to 12 mm. Twenty isolates were screened for production of different lytic enzymes viz. amylase, cellulase, lipase, protease and chitinase. A lot of variation was observed in amylase activity ranging from 0.12 to 2.19 E.I. (Enzyme index). Maximum E.I (2.19) was recorded for isolate KU2 S1 whereas the isolate RO4(5) showed minimum E.I. (0.12).