関東東山地区におけるDMI剤耐性キュウリうどんこ病菌の発生状況
1994 年 1994 巻 41 号 p. 69-75
詳細
1994 年 1994 巻 41 号 p. 69-75
Leaf disc tests taken over a period of 3 years on 324 isolates of cucumber powdery mildew fungus, Sphaerotheca fuliginea (Schlechtendahl: Fries) Pollacci, revealed that a resistant strain to DMIs was distributed widely in the Kanto-Tosan District. The degree of resistance to triflumizole was always less than to triadimefon and fenarimol, although cross resistance among the DMIs was clearly shown. In general field performance of triflumizole was considered to be still good, because triflumizole was the most frequently used fungicide among DMIs registered for cucumber. From 1991 to 1992, the unimodal sensitivity distribution for each DMI tested gradually shifted towards lower sensitivity. However from 1992 to 1993 the reverse was true: sensitivities to DMIs were observed to increase. This phenomenon corresponded to a decline in the number of DMI applications to cucumber in the district. These results indicate that restricted use of DMIs may prevent a further decline in sensitivity of S. fuliginea.
