| Tobacco mildew caused by fungi during storage in Guangxi were investigated and identified, the results showed that Aspergillus spp. were the predominant microflora of tobacco mildew, and Penicillium spp. were the next. Ten isolates of these fungi, which were found frequently in tobacco mildew, were identified as Aspergillus tamarii Kita, Eurotium repens de Bary var. repens, Eurotium chevalieri Mangin, Aspergillus niger v. Tiegh., Aspergillus oryzae (Ahlb.) Cohn var. oryzae, Aspergillus ostianus Wehmer, Aspergillus sclerotiorum Huber, Aspergillus sydowii (Bain. & Sart.) Thom & Church, Aspergillus elegans Gasperini and Penicillium citrinum Thom, respectively.The study on the biological characteristics of A. tamarii, E. repens var. repens and E. chevalieri indicated: For the growth of these Aspergillus, the range of temperature were 16 ℃ -43 ℃, 13 ℃ ~31 ℃ and 16 ℃ ~3 7 ℃, and the optimum were 22 ℃ -34 ℃ , 22℃~28℃ and 22℃~31℃, respectively. Moisture was the most important factor for the growth of these fungi. E. repens var. repens and E. chevalieri started to grow when the relative humidity was 75%, but A. tamarii did not start to grow until the relativehumidity reached 82%; and the higher the moisture was, the faster these fungi grew. All of them have wide adaptability to pH, they could grow even at pH 2.5. A. tamarii grew fast on artificial media, but E. repens var. repens and E. chevalieri grew very slowly. All of them grew fast on natural tobacco leaves media. The better carbon source to A. tamarii were glucose, D-fructose, soluble amylum, saccharose and maltose, while those to E. repens var. repens were glucose, D-fructose, saccharose and D-galactose, and those to E. chevalieri were glucose, D-fructose, saccharose, D-galactose and maltose. The better nitrogen source to A. tamarii were L-tyrosine, sodium nitrate and L-histidine, to E. repens var. repens were sodium nitrate and L-histidine, and to E. chevalieri were L-histidine, glycine, sodium nitrate and L-cystine. The lethal temperature for A. tamarii was 60 °C remaining 20 minutes or 65 °C remaining 10 minutes, for E. repens var. repens was 65°C remaining 30 minutes or 70 °C remaining 5 minutes and for E. chevalieri was 70 °C remaining 15 minutes.The study on the conditions for mildew indicated that moisture and tobacco moisture content (m.c.) were the main factors for tobacco going moldy. When the relative humidity reached 75%, or the tobacco moisture content reached 16%, tobacco was easy infested by pathogens, when the relative humidity was higher than 80%, or the tobacco moisture content was higher than 18%, tobacco mold could develop quickly. Temperature was an important factor influencing the severity of mildew. When temperature was over 20 °C, the pathogens of tobacco mold infested tobacco quickly and severely. Packing material, storage facility and management methods could influence the moisture in warehouse and tobacco moisture content, therefore influence the mold growth and deterioration of stored tobacco.Sensitivities of 10 molds to 7 fungicides were detected in petri dishes,and 4 fungicides with better inhibition were selected for the determination of mildew controlling. The results showed that natamycin 2 OOOmg/kg, dimethyl fumarate 2 OOOmg/kg and potassium sorbate 2 OOOmg/kg could control the growth of microorganisms and prevent mildew damage on tobacco at 18% m.c. , while the effects weren't good at 25% m.c. and 35% m.c. . It suggested that the use of fungicides could provide a supplementary way to control mildew on tobacco.The results also suggested: To control mildew, it was the most effective measure to perfect the storage facility (i.e. ventilation fans or insulation of constructed buildings), meanwhile it was an important measure to make sure that moisture content was optimum when tobacco was putting into warehouse, and the use of weatherproof packages of containers, the use of desiccants, dehumidification, and air conditioning to control the temperature and humidity in warehouse were available ways.
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