The biological properties of tobacco brown spot pathogen,Alternaria alternata werestudied.Thirteen strains from different regions in China were tested in 4 examinations.AS-model curve of growth-temperatures was established based on the colony area of thepathogen strains cultured on PDA medium plate under the conditions of 8 temperature gra-dients.The minimum,optimum and maximum temperatures for the pathogen growth were12~16,20~24 and 36℃,resp.The results of growing 11 strains under 17 gradients of pHproved ...