Occurrence Of Rice Blast And Rice False Smut In 2020 And The Resistance Of Their Pathogens To Fungicides In Jiangsu Province

Rice blast is the main cause of disease in rice production.Distributed throughout the country,rice neck blast,caused by Pyricularia oryzae,directly leads to the serious loss of rice yield;Rice green smut caused by Ustilaginoidea virens(Cooke)Tak.)is an important fungal disease that endangers the rice grain.In recent years,rice blast and rice green smut have posed a serious threat to the production of rice in Jiangsu Province.In order to reduce the incidence of rice-blast in Jiangsu Province,different rice varieties are researched and rice green smut and fungicide resistance are studied.This paper mainly studies the occurrence of rice blast and rice green smut and resistance to fungicides detection to provide practical guidelines for the selection of the main rice varieties in this region,the scientific use of fungicides and effective disease prevention and control.1.The investigation on the occurrence of rice blast and rice green smut in different rice varietiesIn order to grasp the incidence of rice blast and rice green smut in different rice varieties in Jiangsu Province,this study conducted a field investigation on the occurrence of more than 20 main planted rice varieties such as japonica rice Nanjing 5055,Nanjing 5718,and Nanjing 9108.The results showed that the occurrence of rice blast and rice green smut existed in all the investigated varieties,rice neck blast occurred heavily in Nanjing 46,Wuyun jing 23,Yangnong Rice No,1,Huruan 1212,Xiang-ruan-yu japonica and other varieties in southern Jiangsu,the regions along the Yangtze River and Huai River,and Huaibei,with an average rice blast more than 15%,while the rice green smut such as Hui Liangyou seedlings,C Liangyou 1998,Yongyou series and Hui Liangyou 918 were more serious.The investigation also found that early maturing rice was significantly more susceptible to the attack of blast in rice neck,leaves and seedlings as compared to late maturing rice(P<0.05).2.The resistance test of rice blast and rice green smut to Isoprotholane and Propiononazole in Jiangsu ProvinceTo clarify whether the sensitivity of rice blast and rice green smut to Isoprotholane and Propiononazole has changed,this study tested the resistance of rice blast and rice green smut to Isoprotholane and Propiononazole in Jiangsu Province.The results showed that Pyricularia oryzae had low resistance risk to Isoprotholane,with a frequency of 15.2%,average EC50 of 5.2 mg/L,and resistance level between 1.3 and 2.9.Resistance in different regions are different.For instance,Nan japonica 5055 in Nanjing and Taizhou had no reflections,but that in Nantong had.The frequency of U.virens(Cooke)Tak.to Propiononazole resistant strains was 51.2%,but the resistance level was between 0.2 and 1.6,which is below the sensitive strain threshold 5,indicating that the rice varieties tested were susceptible to prop ionazole.