培养条件及杀菌剂对玉米穗腐病菌可可毛色二孢生长的影响

可可毛色二孢（Lasiodiplodia theobromae）穗腐病是近年来发生在玉米上的一种新病害。本文研究了不同培养基、温度、pH、碳源和氮源对该病原菌生长的影响，并评价了 8 种杀菌剂对该病原菌的抑制效果。结果表明，25 ℃培养 1 d 后，可可毛色二孢在 PDA 和 MLPA 两种培养基上生长速度最快，菌落直径分别为 49.88 mm 和48.13 mm，显著大于其他处理（p<0.05）；最适合该病原菌生长的温度为 30 ℃，培养 1 d 后菌落直径为 61.88 mm，显著大于其他温度处理（p<0.05）；在 55 ℃处理 10 min 后的菌落不能继续生长；最适合该病原菌生长的 pH 为 6，25 ℃培养 1 d 后菌落直径可达到 75.00 mm，显著大于其他处理（p<0.05）；淀粉和硝酸钠分别为可可毛色二孢生长所需的最佳碳源和氮源，在上述两种培养基上培养 1 d 的菌落直径分别为 58.13 mm 和 37.13 mm，均显著大于其他处理（p<0.05）。咯菌腈、甲基硫菌灵和异菌脲对可可毛色二孢有较好的抑制效果，EC50 均小于 1 mg/L。本研究结果为深入了解可可毛色二孢玉米穗腐病的发生规律和制定有效防治策略提供依据。

Effects of Culture Conditions and Fungicides on Growth of Lasiodiplodia theobromae Causing Maize Ear Rot

Maize ear rot caused by Lasiodiplodia theobromae is a new disease reported in recent years. In this study, the effects of different media, temperatures, pH value, carbon and nitrogen sources on the growth of L. theobromae were investigated, and the inhibitory activity of 8 fungicides to this pathogen was evaluated. After incubation at 25 ℃ for 1 day, the best growth of L. theobromae was recorded at PDA and MLPA media with the colony diameters of 49.88 mm and 48.13 mm, respectively, which were significant greater than those of the other treatments (p<0.05). The optimal temperature for L. theobromae growth was 30 ℃ with the colony diameter of 61.88 mm, which was greater than that of the other treatments (p<0.05), and no mycelial growth was noted at 55 ℃. pH 6 was best for L. theobromae growth at 25 ℃for 1 day with the colony diameter of 75.00 mm, and there was a significant difference between this treatment and the others (p<0.05). On the media amended with starch and sodium nitrate, the colony diameter was 58.13 mm and 37.13 mm, respec-tively, which were significantly higher than that of the other treatments (p<0.05). The EC50 values of fludioxonil, thiophanate-methyl and iprodione to L. theobromae were less than 1 mg/L, indicating that these three fungicides performed well on inhibiting the growth of this pathogen. The results would provide a basis for further understanding the occurrence regularity of maize ear rot caused by L. theobromae and making effective management strategy.