Resistance of Botryodiplodia theobromae to carbendazim and the fungicides screening using stem end rot of mango fruit as a control.

The resistance to carbendazim of 86 isolates of mango stem end rot pathogen Botryodiplodia theobromae Pat.collected from 3 regions in Hainan province was tested in vitro.The toxicity of 23 fungicides to 4 isolates of B.theobromae was tested by mycelium growth rate methods.The toxicity results were analyzed by the EC50 value,the EC90 value and the crossresistance to each other.Results showed that 10 fungicides including sporgon,propiconazole,flusilazole,prochloraz,iprodione,difenoconazole,tebuconazole,myclobutanil, pyraclostrobin and validamycin A were recommended for choices for controlling mango stem end rot disease.In addition,the fungicides of chlorothalonil and mancozeb could also be chosen.The re-sistance to thiophanate-methyl,kresoxim-methyl,and diniconazole was appeared in the tested pathogens.In cross-resistance test, the results showed that carbendazim,kresoxim-methyl and diniconazole had cross-resistance each other,while kresoxim-methyl and validamycin A had negative cross-resistance each other.To avoid the resistance of the pathogen to some of the fungicides,such fungicides should be used by turns.