| The leaf spot of rubber tree caused by Lasiodiplodia theobromae was a new rubber trees disease in Guangdong, Hainan and Yunnan Province. In order to provide theoretical basis for effective prevention and control of this leaf spot on rubber tree, the biological characteristics of L. theobromae and the selection of high efficiency and low toxicity fungicides were studied in this study. The biological characteristics of this pathogen was analysed by conventional methods. The toxicity of ten fungicides to L. theobromae was tested by the method of mycelia growth inhibition. The results showed that the optimum growth temperature of L. theobromae was 30℃ the most suitable growth pH ranged from 6 to 8; the lethal temperature was at 53℃ for 10 min; the best carbon source for mycelial growth was glucose; the best nitrogen source was beef extract. Different light treatment had significant effects on growth of mycelia and 24 h lighting condition was most suitable to growth of mycela. The result indicated that the toxicity to this pathogen of these fungicides was significantly different. Among these ten the fungicides, we found that carbendazim showed the best efficiency with the value of EC50 0.0675 μg/mL and the following one was thiophanate-methyl with the value of EC50 0.2019 μg/mL. L. theobromae was a thermoacidophilic fungi，while it can be inhibited by carbendazim, propiconazole, thiophanate-methyl and difenoconazole to prevent leaf spot. |
