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Root Rot Disease Caused by Fusarium solani on Gromwell in Korea

Gyoung Hee Kim: Sunchon National University

<div>Wilted plants caused by root rot were frequently observed in the open-fields of gromwell in Jindo, Jeonnam province in Korea. Early in the course of the disease, affected plants showed wilted leaves and dark brown necrosis symptoms on stems near soil line. As the disease progressed, rotted roots were disorganized and whole plants resulted in death. A fungal isolate of <em>Fusarium</em> sp. was consistently obtained from symptomatic stems or roots and produced microconidia, macroconidia and chlamydospores on a carnation leaf agar plate. The fungal isolate of <em>Fusarium</em> sp. fulfilled Koch’s postulates for establishing the causal agent of root rot on gromwell. On the basis of mycological, pathological characteristics and ITS rDNA sequences, the pathogen of root rot on gromwell was identified as <em>Fusarium solani</em>. Optimum temperature ranges for the mycelial growth of the pathogen were 24~27℃. Wounds were necessary for the pathogen to infect gromwell plants in the fields. Overall incidence rates of root rot on gromwell were 53.7~100% in open fields during the survey periods from 2009 to 2011, but they were 0~35.0% in rain-proof polyvinyl houses. Installation of rain-proof shelter could alleviate the occurrence of root rot epidemics known to be the most problematic limiting factor for the stable cultivation of gromwell in Jindo Island which heavy rainfalls and strong winds occurred frequently during the growing seasons of gromwell.</div>