烯酰吗啉对我国烟草黑胫病菌的毒力研究

Inhibitory Effect of Dimethomorph on Phytophthora parasitica var.nicotianae in China

从山东和云南烟区采集分离了20个烟草黑胫病菌phytophthora parasitica vat．nicotianae菌株，采用菌丝生长速率法测定了烯酰吗啉对这些菌株的毒力。结果表明：20个田间菌株的EC50值在0．60-1．28μg/mL之间，与实验室保存的敏感菌株（S）的EC50值（0．32μg/mL）相比，毒力倍数在1．87—4．00之间．均属于敏感菌株。烯酰吗啉对烟草黑胫病菌孢子囊的产生有明显的抑制作用，8．00μg/mL的烯酰吗啉对孢子囊产生的抑制率为100％。通过烯酰吗啉对烟草黑胫病菌继代培养物的毒力比较证明，烟草黑胫病菌对烯酰吗啉存在抗性风险。

The inhibitory effect of dimethomorph on 20 strains of Phytophthora parasitica var. nicotianae,which isolated from Shandong and Yunnan province, were determined by using mycelium growth rate method. The results showed that EC50 values of 20 strains were ranged from 0.60 to 1.28 μg/mL, Compared with of the sensitive strain EC50 value, the inhibitory factors were ranged from 1.87 to 4.00, which indicated that the 20 strains were sensitive to dimethomorph. Dimethomorph could evidently inhibit the formation of sporangia. The inhibitory rates against the sporangia formation of P. parasitica was 100% by 8. 00 μg/mL dimethomorph. The resistance risk of P. parasitica to dimethomorph was proved by testing on inhibitory activity of dimethomorph to mycelial growth of the sub-culture fungus.