Abstract:

In order to clarify the pathogen species of heart rot of Acacia mangium in the initial stage and provide the basis for the early diagnosis and prevention of the disease, the author collected 36 diseased samples from asymptomatic 6-year-old living tree of Acacia mangium from a stand at Longyandong forest farm in Guangdong Province, from which 3 species of basidiacota fungi were isolated. The pathogenicity of 3 basidiacota fungi was tested through inoculation them to 1-year-old branch on 6-year-old living tree in field and the wood block of Acacia mangium in culture dish. The results showed that the pith of branches macerated and turn brown and the average infective depth of these 3 basidiacota fungi were 5.0 cm, 2.4 cm, 7.0 cm 20 days after inoculation, and the wood weight loss were 25.88%, 31.48%, 21.02%, respectively 61 days after inoculation at 25℃. 3 basidiacota fungi were amplified by PCR technique with universal primers of fungi, and the sequences of the internal transcribed spacer of their ribosomal DNA were further compared with that in GenBank. Combined with their cultural characteristics, the 3 pathogenic fungi were Phanerochaete avllanea, Peniophora aurantiaca, and Phlebia brevispora. The conclusion was that: Phanerochaete avllanea, Peniophora aurantiaca, and Phlebia brevispora, all of them had capacities to infect the healthy branch of live tree and decay the wood blocks, and they were pathogens of heart rot of Acacia mangium in the initial stage.