Study On Occurrence Relation Of Aphids And Yellow Dwarf Disease In Winter And Spring Wheat Intercropping Area Of Qinghai

In recent years, because of the adjustment of crop planting and the change of climate conditions, wheat crop diseases has become more and more serious in Qinghai province and the wheat yellow dwarf has become the main disease. Occurrence of wheat yellow dwarf were studied systematically in the important wheat growing area(Guide) in Qinghai of 2013 and 2014. The species of the strains and proportion of Barley yellow dwarf virus that aphids carry in Qinghai were tested in the method of molecular ecology experiment.The main results are as follows:1.The species of aphids in Qinghai were Sitobion avenae, Schizaphis gramium and Rhopalosiphum padi. Sitobion avenae was the dominant specie of aphids and 68%-95% were it. The wheat aphids can overwinter in tillering node, root and soil of wheat near the adret ridge in winter and spring wheat intercropping area.2.In Guide, the aphids overwinter in winter wheat field, The wheat infected BYDV was the source of virus of next year. After winter wheat turned green next year, the number of Aphid increased gradually and reached the peak in wheat filling stage. With the maturity of winter wheat, the number of winged aphids increased and the aphids migrated to grassy weeds and spring wheat to survive summer gradually. In spring wheat field, the winged aphids began to appear in jointing stage. The number of aphid reached the peak in wheat filling stage.With the beginning of mature stage, winged aphids moved to gramineous weeds and authigenic wheat. The aphids migrated back to overwinter in winter wheat. The BYDVs were spread with aphids.3.BYDVs mildly occurred in 2013,the maximum disease index was 3.57 and the incidence was 4.06%. BYDVs mildly spread in 2014, the maximum disease index was 6.91 and the incidence was 7.90%.4.99.68% of BYDVs were GAV, It was predominant.A few was the mixing infection of GAV and PAV.GPV of BYDV was not founded in 2014 in Qinghai.5.The Barley yellow dwarf virus carrying ratio of aphids was 37.5%-80.65% before overwintering in winter wheat planting area in 2014 of Qinghai. The average was 64.29% and 98.76% were BYDV-GAV, and BYDV-GAV was not founded.