Cultivar reaction and efficiency of chemical control of aphid vectors of barley yellow dwarf virus in wheat.

摘要

Four experiments were conducted in Cruz Alta, Rio Grande do Sul, Brazil, during 2000 to study the reaction of 4 wheat cultivars (Fundacep 30, Fundacep 31, Fundacep 36 and Fundacep 37) to barley yellow dwarf virus (BYDV), and to evaluate the efficacy of thiamethoxam, imidacloprid and chlorpyrifos against the aphid vectors of BYDV. Rhopalosiphum padi was the dominant aphid species collected (75%); Metopolophium dirhodum (16.2%), Sitobion avenae (7.5%) and Schizaphis graminum occurred at low densities. Only Fundacep 31 showed a positive reaction to ELISA, confirming the presence of BYDV-PAV, BYDV-MAV and BYDV-SGV. Fundacep 30, Fundacep 36 and Fundacep 37 were resistant, whereas Fundacep 31 was susceptible to BYDV. Seed treatment with imidacloprid and thiamethoxam at 24.5 g/100 kg of seeds effectively controlled the aphid vectors, and these treatments were more effective than the conventional foliar sprays of chlorpyrifos. Seed treatment with imidacloprid and thiamethoxam at rates higher than 8.5 g/100 kg of seeds reduced grain yield losses associated with the aphid-BYDV complex.