The Preliminary Study To Epidemic Factors Of Powdery Mildew In Mid-GanSu And Detection Of Fungicide Resistance Of Blumeria Graminis F.sp.tritici To Triadimefon In Part Wheat Regions In China

In order to analysis the epidemic factors of powdery mildew in wheat regions in mid-GanSu,constuction of virulent gene of the fungi and disease index caused by different level fertility were studied in severe areas in dry-land. (1) The virulent gene structure in wheat reigon in mid-GanSu was studied by thirty-two varieties resistant to powdery mildew.the result showed that v1,v3c,v3f,v4a,v5,v6,v7,v8,v17,vera had represented strong virulence,detection frequency ranged from 70 percent to 100 percent,v2 ,v3a ,v3b ,v19 had had low virulence,detection frequency ranged from 10 percent to 80 percent, v1+2+9,v2+6,v2+mld,v2+talent,v4+8,v4+2x,v4b,v4+mli+5,v5+6,v5+mli,v13,v20,v21,vxbd had been immune, detection frequency ranged from 70 percent to 100 percent.the relevant varieties including Axminster/8cc(v1) ,Sonora/8cc(v3c) ,Michigen Amber/8cc(v3f) ,Khapli/8cc(v4a) ,Hope/8cc(v5) ,Timgalen(v6) ,CI14189(v7),Gaojiasuo(v8),Amigo(v17) had already lost their resistance to powdery mildew in the corresponding areas,they had already lost their resistant value in produce.the resistances of varieties involed Ulka/8cc(v2),Asosan/8cc(v3a),Chul/8cc(v3b),Pm(v19) would need to be more studied.The immune varieties consisted of Normadie(v1+2+9),Maris Hantsman,CI12632,Coker747(v2+6),Maris Dove(v2+mld) ,Brock(v2+talent) ,Kenguia(v4+8) ,Baitu3(v4+2x) ,Armada(v4b),Misson(v4b+5+mli),Coker983(v5+6),Agulia(v5+mli),Chinese Spring R4A (v13),Pm(v20),M599(v21),Xiaobaidongmai(vxbd) had been mostly claimed attention in the future.the cluster analysis showed three stations detected in winter spring areas was earlier than other six stations detected in spring wheat aera except Baiying spring,and the result from correlation coefficient showed the correlation of winter and spring wheat areas varied from 90.74 percent to 96.12 percent.the results illuminated that the virulent gene structure of wheat podwey mildew was very parallel,the primary infectious source of wheat powdery mildew in spring wheat areas was very possible from winter spring areas. (2) The effect of the different fertility on spring wheat powdery mildew in dry-land was studied.the results showed that the high level nitrogenous fertilizer or high level nitrogenous fertilizer cross normal level phosphorus fertilizer was significantly relative to disease index of wheat powdery,and disease was negatively relative to yield,single phosphorus fertilizer was not significantly relative to disease index,and disease did not significantly affect on yield,but disease index was comparatively lower in the treatment of normal level nitrogenous fertilizer cross normal level phosphorus fertilizer(75.0 kg/ha N+300kg/ha P) in cross treatment,and yield was comparatively higher.it clarified that nitrogenous logically cross phosphorus fertilizer would lighten disease index,and would yet contribute to improve yield. Aiming at the actuality of difficult control to powdery mildew in LongNan region in GanSu and the same status in Sichuan,Beijing,Henan,Hebei,Shandong,the fungicide resistance of 204 isolates of wheat powdery mildew(Blumeria graminis f.sp.tritici) to triadimefon was tested by vitro leaf-tip in 2004, the results showed that the mean resistance factor was 39.30 in 2004,the mean frequency of resistant isolates was 96.08 percent,the highest resistance factor was 361.64,the resistance factor from 10 to 40 reached 54.41 percent,the resistance factor over 40 was 32.84 percent.the resistance frequency of isolates from Sichuan and Shandong was all 100 percent.the resistance factor in Sichuan was most serious and the resistance factor over 40 was 68.42 percent,high resistant isolates was most,while the resistance factor of isolates from Beijing,Henan,Hebei,Gansu,Shandong was 10 to 40,the middling resistant isolates was more.the resistance frequency was relaticely lower,the sensitive isolates was relatively more.the results firstly tested in Wenxian,Wudu,Dongjiangshuiping in Gansu showed that the mean resistance factor was 38.95, the mean resistance frequency was 97.06 percent,the highest resistance factor was 233.49.the resistance factor of isolates from Wenxian and Wudu was higher than Dongjiangshuiping,but the resistant isolates from 10 to 40 in three regions was over 50 percent.