The Main Biological Characters And Control Technology Of Rice Sheath Blight In Liaoning Province

Rice sheath blight,which is a kind of international disease in the north and the south rice area occurs frequently in our country,in recent years in the north,the disease incidence trend has become one of the main obstacle to limit high yield and stable yield of rice.In this experiment,by studying the rice sheath blight fungus cell wall degradation enzymes,mycelial growth rate,sclerotia number and dry weight of Rhizoctonia solani.In 2017,the disease dynamics of rice sheath blight was monitored at the test site in Panjin,Liaoning Province.Biological pesticides and high-efficiency and low-toxic chemical pesticides were selected for field trials on rice sheath blight control and rice yield.Based on the above conclusions,a set of synthetical prevention systems for rice sheath blight in Liaoning Province was established based on the effects of fertilization methods and water management methods on the occurrence of rice sheath blight.1.The relationship of main biological characters of rice sheath blight in Liaoning Province.In terms of mycelial growth rate,there was a significant difference in mycelial growth rate between different counties and cities in liaoning province.The growth rates of R.solani from Tieling City was the fastest,32.44 mm/d,while the slowest from Panjin City,25.68 mm/d.Type B strains accounted for the most,43.75%,and type A strains accounted for the least,22.92%.In terms of the number of sclerotia and the dry weight of sclerotia,there was a significant differences between different counties and cities in Liaoning Province.The number of sclerotia of R.solani from Yingkou City was the most,42.97,while the least from Dalian City,24.19.Type C strains accounted for the most,53.13%.Type A strains accounted for the least,0%.The dry weight of sclerotia of R.solani from Yingkou City was the most,0.046 g,while the least from Dalian City,0.021 g.In terms of the activity of PG enzyme and PMG enzyme,there was a significant difference in the activity of PG enzyme and PMG enzyme in rice sheath blight from different counties and cities in Liaoning Province.The activity of PG enzyme of R.solani from Dalian City was the highest,188.47 U/m L,while the lowest from Panjin City,94.52 U/m L.The activity of PMG enzyme of R.solani from Dandong City was the highest,90.76 U/m L,while the lowest from Dalian City,61.79 U/m L.2.Establishment of a prevention and control technology system for rice sheath blight in Liaoning Province.In 2017,the rice sheath blight disease occurred in late June and expanded rapidly after July 6,and disease growth stopped until August 31 in Panjin,Liaoning Province.Among the 10 fungicides tested,pyraclostrobin and difenoconazole propiconazole had the highest control effect on rice sheath blight,and the control effect was 81.7% and 80.0%.Phenazine-1-carboxylic acid has the lowest efficacy,which is 40.0%.Pyraclostrobin and hexaconazole occupied the highest and lowest yield increasing rates,which were 11.6% and 1.1%,respectively.Different water management methods have a great influence on the occurrence of rice sheath blight.The disease index of rice sheath blight in the final stage of tillering was much lower than that in deep water management.The disease index of rice sheath blight in two surveys of drying paddy field was investigated in the final stage of tillering at 8.56 and 15.2,respectively.The disease index of rice sheath blight in two surveys of deep water management were 19.6 and 62.3,respectively.The output of the final tillage of drying paddy field was also higher than that of deep water management,with the yields of 11184 kg/hm2 and 10021 kg/hm2,respectively.Different fertilization methods also had a great influence on the rice sheath blight.After applying the ear grain fertilizer in the late growth stage,the disease index of the two surveys were 10.5 and 14.2,respectively.Without the application of ear grain fertilizer,the disease index of the two surveys was 2.4 and 3.8 respectively.The yield of the grain-fertilizer treatment was 11977 kg/hm2 in the late growth stage,and without applying the ear grain fertilizer the yield was 11538 kg/hm2.