Potential of antagonistic endophytes against bacterial blight of anthurium

Abstract

One of the major constraints in anthurium cultivation is the severe incidence of bacterial blight disease. The pathogen causing bacterial blight of anthurium was isolated and identified as Xanthomonas axonopodis pv. dieffenbachiae based on its cultural, morphological and biochemical characters coupled with its pathogenicity. Endophytic microbes were isolated from different parts of healthy anthurium collected from various locations of Thrissur, Kannur, Kasargod and Thiruvananthapuram districts. Isolation yielded more number of bacteria than fungi. Out of 51 endophytes tested, only eight bacterial and two fungal isolates showed antagonism against the pathogen. The eight selected bacterial endophytes were subjected to various tests for understanding the parameters that may act to produce antagonism as well as enhanced growth of the plants. The antagonists varied in their ability to promote plant vigour, hydrogen cyanide, IAA, ammonia and siderophore production and Phosphorus solubilization capacity. The endophytes were compatible with Bavistin, Akomin and Contaf and incompatible with Indofil M 45, Saaf and Captaf. Six insecticides viz., Classic, Rogor, Ekalux, Malathion, Target and Hostathion, and four fertilizers viz. Muriate of potash, Rajphos, Urea and Factomphos were compatible with the isolates. However, the isolates exhibited variation in their sensitivity with the antibiotics tested. Further, all isolates were compatible to each other. A pot culture experiment was conducted to assess the field efficacy of selected endophytes in comparison with recommended management practices. The treatments were given as two pre inoculation and two post inoculation sprays. The incidence and severity of the disease were recorded at five days interval for a period of 30 days. The result indicated that plants treated with endophyte EB15 showed minimum disease incidence and severity. This was followed by treatment with EB 31 and Streptocycline. The promising endophytes, EB15 and EB 31 were tentatively identified as Bacillus sp. and Pseudomonas sp. respectively.