Suppression of Citrus Melanose on the Leaves Treated with Rhizobacterial Strains after Inoculation with Diaporthe citri

Research in Plant Disease 2012;18(4):331-337.
Published online December 30, 2012.

식물근권세균 처리에 의한 감귤 검은점무늬병에 대한 방제 효과

고윤정 ( Yun Jung Ko, ) , 강소영 ( So Young Kang ) , 전용철 ( Yong Chull Jeun )

Suppression of Citrus Melanose on the Leaves Treated with Rhizobacterial Strains after Inoculation with Diaporthe citri

Yun Jung Ko, So Young Kang and Yong Chull Jeun*

Major of Plant Resources & Environment, College of Applied Life Sciences, The Research Institute for Subtropical Agriculture and Biotechnology, Jeju National University, Jeju 690-756, Korea

Received: August 28, 2012 Revised: November 05, 2012 Accepted: November 16, 2012

Abstract

Citrus melanose is one of important disease in citrus cultivation, reducing quality of citrus fruits and resulting in economic loss. Like other diseases in citrus, melanose was mainly protected by chemical fungicide in the field. Recently, alternative method of disease control is highly required due to the side effect of the chemicals. In this study four rhizobacterial strains TRH423-3, MRL408-3, THJ609-3, and TRH415-2 are selected by dual-culture testing its antifungal activity against Diaporthe citri causing citrus melanose. To investigate the protection efficacy of the selected rhizobacterial strains to citrus melanose, the bacteria were pre-treated on citrus leaves following inoculation with melanose pathogen. Pre-treatment with all selected rhizobacterial strains showed disease suppression in which the levels of protection rates were different by the rhizobacterial strains. Additional treatment with the rhizobacterial strains after the pathogen inoculation enhanced protection rates in all cases. The strain MRL408-3 and TRH423-3 were identified as Burkholderia gladioli, TRH415-2 as Pseudomons fluorescens and THJ609-3 as Pseudomonas pudia as a result of analyzing the internal transcript spaces of the rhizobacterial strains rDNA. The selected rhizobacterial strains may be valuable as biological control agents in the environment-friendly citrus farm in which chemical application is limited.

Key Words: Bio-fungicide, Biological control, Environment-friendly, Internal transcribed spacer