Development of pre-detection technique for bacterial blight (Xanthomonas axonopodis pv. dieffenbachiae) disease in Anthurium to produce healthy planting materials

Abstract

Anthurium cut-flowers and potted plants have earned a growing marketing demand both in the local and global markets. Bacterial blight, caused by Xanthomonas axonopodis pv. dieffenbachiae has been of major economic concern among the growers worldwide as the disease could cause heavy losses on Anthuriums and other members of the family Araceae. The disease has the potential of spreading latently exhibiting no symptoms through a range of hosts and this fact makes it a prerequisite to detect the presence of pathogen early. No reliable control method so far has been developed and therefore maintenance of strict crop sanitary measures is of great importance. 100 samples representing 30 nurseries were selected from three of the major producing districts, Gampaha, Kurunegala and Puttlam districts. The pathogen was isolated from the samples using 5% KOH test and yeast dextrose calcium carbonate medium. Isolated pathogen was inoculated to healthy Dieffenbachia cane and leaf slices and after 1 – 2 days, symptoms first developed in cane cuttings while leaves took three days for the development of symptoms. Young, tender leaf and cane slices were observed to be highly susceptible to disease. The mature cane slices and leaf cuttings were found to be resistant to the pathogen, most probably due to the non-specific mechanical impermeability of the tissues. Tender leaf and cane tissues, with their ability to get infected and develop visual symptoms relatively fast, worked best with the technique as they proved to shorten the time taken for the detection. The validity and the precision of the pathogen identification test and therefore, the method, were assessed with an indirect-ELISA pathogen-specific detection step, prior to inoculation of healthy tissues. Pathogen was detected to present in 15 samples from Kurunegala and Gampaha districts. The method confirmed its precision, reliability, cost-effectiveness and application under normal laboratory conditions.