Sensitivity of Magnapothe grisea at Different Development Stagesto Seven QoI Fungicides

The sensitivity of Magnapothe grisea in vitro at different development stages to six innovative QoI fungicides by China was studied adopting azoxystrobin as the control fungicide.Results showed that these 7 QoI fungicides had strong activity on mycelia growth of M.grisea with EC50 values ranging from 0.10 to 2.89 μg/mL,spore yield and spore germination with EC50 values ranging from 0.10 to 4.92 μg/mL and 0.75 to 7.14 μg/mL,respectively.The inhibition rate of spore yield on 1.0 μg/mL enestroburin-,azoxystroburin-,SYP-3375- and SYP-2815- amended media was higher than 90%.Seven QoI fungicides could inhibit the length of germ tube of M.grisea with EC50 values ranging from 1.67 to 34.76 μg/mL.It could not affect the formation of mycelia,but strongly inhibit melanin biosynthesis of M.grisea on 1.0 μg/mL fungicide-amended media.