First report of black root disease caused by Chaetomium globosum on rubber tree seedlings in Yunnan, China.
In September 2016, a new disease of the root tips of rubber tree seedlings (Hevea brasiliensis) was found in Jinghong City, Yunnan, China. Diseased seedlings had stunted, blackened, but not rotten root tips. The disease incidence at the seedbeds could reach as high as 98%. Some stems of the seedlings developed lesions or cankers, but their leaves were free of any disease symptoms. Samples of infected root tips were collected for pathogen isolation and identification. Based on morphological characteristics, DNA sequencing and pathogenicity, the causal agent was identified as Chaetomium globosum. This fungus has been reported to cause leaf blight disease of Chrysanthemum morifolium in Zhejiang, China, and decay the stem tissues of the H. brasiliensis. Here, Chaetomium globosum caused failed development of the main roots in rubber seedlings, resulting in susceptibility to wind and proneness to toppling later in their lives. This is thought to be the first report of this pathogen involved in disease in H. brasiliensis in China occurring in the early phases of the host life.