草海桐链格孢叶斑病菌生物学特性及杀菌剂的室内筛选

西沙群岛草海桐链格孢叶斑病发生普遍,前期笔者鉴定了该病的病原菌为长柄链格孢菌（Alternaria longipes）。为进一步明确该病原菌的生物学特性及其对杀菌剂的敏感性,采用生长速率法对长柄链格孢菌的生物学特性进行了初步研究,并测定了苯醚甲环唑等13种杀菌剂对该病原菌的室内毒力。结果表明：该菌菌落最适生长培养基为马铃薯葡萄糖固体培养基（PDA）,其次是马铃薯蔗糖固体培养基（PSA）;适宜生长温度范围为25~30℃,最适生长温度为28℃;适宜生长pH为5.0~7.0,最适pH为6.0;最佳碳源为蔗糖,而果糖不利于菌落生长;最佳氮源为甘氨酸,而尿素不利于菌落生长;光照时间对菌落生长无显著影响。室内毒力测定表明,苯醚甲环唑水分散粒剂的抑菌效果最好,EC₅₀值为0.15 μg/mL,其次是氟硅唑乳油、己唑醇悬浮剂和戊菌唑乳油,其EC₅₀值分别为0.37、0.44和0.51 μg/mL,嘧菌酯悬浮剂和多菌灵可湿性粉剂的抑菌效果最差,EC₅₀值均大于3000 μg/mL。

Biological Characteristics of Alternaria Leaf Blight of Scaevola taccada and Screening of Fungicides in vitro

Alternaria leaf blight of Scaevola taccada is a common and serious disease in Xisha Island. The pathogen of the disease was identified as Alternaria longipes. To further clarify the biological characteristics of the pathogen and its sensitivity to fungicides. Therefore, in this study, the biological characteristics of A. longipes were preliminarily studied by the mycelium growth rate method, and the toxicological test of 13 fungicides such as difenoconazole to this pathogen was determined. The optimum growth medium was potato dextrose agar medium (PDA), followed by potato sugar agar medium (PSA). The suitable growth temperature was 25 to 30℃, and the optimum growth temperature was 28℃. The suitable pH value was 5.0 to 7.0, and the optimum pH value was 6.0. The optimal carbon source was sucrose, while fructose was not conducive to colony growth. The optimal nitrogen source was glycine, while urea was not conducive to colony growth. Light time had no significant effect on colony growth. Laboratory toxicity test showed that the best inhibition effect was found in difenoconazole water-dispersible granular with EC₅₀ value of 0.15 μg/mL, followed by flusilazole emulsion, hexazolium suspension agent and penconazole emulsion, with EC₅₀ values of 0.37, 0.44 and 0.51 μg/mL, respectively, while azoxystrobin suspension agent and carbendazol wettable powder had the worst inhibitory effect, with an EC₅₀ value of more than 3000 μg/mL.