Synergistic Control Effects Of Resistant Varieties With Chemical Agents To Wheat Crown Rot

Wheat crown rot has become one of the main problems in wheat production safety in Hebei province.At present,the wheat resistant varieties of crown rot in Huanghuai wheat region are very scarce,and there is no effective chemical agents to control the disease.In this paper,the main wheat resistant varieties and highly effective control agents in Hebei province were selected by laboratory pot experiment and toxicity test.The effects of chemical agents with resistant varieties on the growth index of wheat and the incidence of of wheat crown rot were determined in three fields a year.It provides part of the theoretical basis for the establishment of the prevention and control technology system of wheat crown rot.The main research results are as follows:1.The Main Wheat Varieties in Hebei Province had no immunity or high resistance to crown rot.Among them,Handan and Shijiazhuang had the highest incidence of wheat,accounting for 41.2% and 29.5%of the total varieties.The incidence of wheat crown rot in other areas from high to low was Xingtai,Cangzhou,Baoding and Hengshui.Jimai 22 showed medium resistant,and the disease index was 18.42.Gaoyou 2018 and Xingmai 7 were susceptible,disease index was 26.57.The other varieties were highly susceptible,and the disease index of all highly susceptible varieties higher than 62,accounting for 88.5% of the total number of tested varieties.2.The virulence showed strongest effected on the mycelial growth,spore germination and spore production of Fusarium graminearum causing wheat crown rot in Hebei Province,and the EC₅₀ values were 0.2183 g/mL,0.0915 g/mL and 1.940 g/mL,respectively.Followed by Tebuconazole,Chlorothalonil and Mancozeb.Azoxystrobin,Mancozeb and Imidaflutamide were lower.The strains HB-NH and SD-DZ had the highest sensitivity to Nitronitrile.With increasing of the agent concent,the mycelium twisted severely and stretched in a wavy shape,and branch were increase rapidly and the Angle was 90,and the mycelia of fusarium SD-DZ was in a state of spiral elongation.3.In the three experimental areas of Wangdu,Xinji and Ningjin,the medium-resistant variety Jimai 22 combined with 2.5% Nitronitrile 150 mg/L had high control effect on wheat crown rot.Overwintering 2.5% Nitronitrile 150 mg/L seed dressing,the control effects of 150 mg/L of Nitronitrile on wheat crown rot were 60.0% and 55.3%respectively;the control effect at jointing stage was generally lower than that at seedling stage,and the mean defensive effectiveness was 52.0% and 46.5% respectively;the control effect of grouting period was basically the same as that of jointing period,and the mean defensive effectiveness was 42.1% and 37.2%respectively.They were significantly higher than the control agent treatment of 3%Difenoconazole,and it is only next to Nitronitrile 200 mg/L seed dressing treatment.The control effect of 100 mg/L of Nitronitrile on wheat crown rot was poor.The average defense effect of deep turning is below 30%and that of rotary tillage is below 20%,and there was no significant difference between the two groups.4.The medium-resistance variety Jimai 22 is combined with 2.5% Nitronitrile 150mg/L combined with deep-turning treatment to further promote the growth and development of wheat.2.5% of the flavonoid 150 mg/L of the seed dressing at the jointing stage,the average number of stems per plant increased by 5.4% compared with the control,and the plant height increased by 6.2%;the average number of stems per plant increased by 3.6% and the plant height increased by 4.9% during grain filling,1the growth rate of resistant varieties was significantly lower than that of susceptible varieties.The number of stems and the number of secondary roots of each treatment were not different from those of the control.5.In Wangdu,Ningjin and Xinji experimental areas,150 mg/L 2.5%Nitronitrile suspension seed dressing agent,supplemented by deep turning,increased yield by 12.9%,10.9%and 11.8%,respectively,after 2.5% Nitronitrile suspension seed dressing agent 200mg/L,which was significantly higher than that of 3%Difenoconazole suspension seed dressing agent control agent.The effect of field application is the best.