The Occurrence Of Diseases, Insect Pests And Weeds Of Double-cropping Rice Under Mechanized Rotary Tillage And Its Control Technology

Rice is the main cereal crops in China, the double-cropping rice is the main plantingpattern in south China, and the mechanized rotary tillage is the main way of ploughingpromotion of paddy fields in recent years. Based on the investigation of occurrence ofdiseases, control techniques of several pesticides on diseases, insect pests and weeds ofdouble-cropping rice under mechanized rotary tillage were studied by indoor and field tests,and a FSC, which controled plant diseases and insect pests in the seedling stage, wasdeveloped. Results are as follows:1Four patterns such as mechanized rotary tillage-mechanized transplanting method,mechanized rotary+cattle tillage-mechanized transplanting method, cattletillage-mechanized transplanting method and mechanized rotary tillage-manualtransplanting method were tested in order to investigate the effects of differentplowing-transplanting methods on diseases, insect pests, weeds and yield ofdouble-cropping rice. Results showed that major diseases, insect pests and weeds weresheath blight disease(Rhizoctonia solani), Cnaphalocrocis medinalis, Monochoria vaginalisand Echinochloa crusgalli in early rice with four plowing-transplanting methods in nousing pesticide areas, and sheath blight disease, C. medinalis, rice planthopper(Sogatellafurcifera and Nilaparvata lugens), M. vaginalis and E. crusgalli in late rice. Under the sameconditions of fertilizer and water management, the sheath blight which was more serioususing mechanized rotary tillage-manual transplanting method than that using mechanizedrotary tillage-mechanized transplanting method, and more serious using cattletillage-mechanized transplanting method than that using mechanized rotarytillage-mechanized transplanting method. The occurrence difference of C. medinalis wasnot significant between four plowing-transplanting methods in early and late rice. Thepopulation density of rice planthoppers in late rice was low at early stage, which washighest using mechanized rotary tillage-manual transplanting method, and lowest usingmechanized rotary tillage-mechanized transplanting method. The weeds’ density washighest in early and late paddy fields with cattle tillage-mechanized transplanting method,followed by mechanized rotary+cattle tillage-mechanized transplanting method andmechanized rotary tillage-mechanized transplanting method, and lowest with mechanizedrotary tillage-manual transplanting method. Variance analysis indicated that there was nosignificant difference in the yield between four kinds of plowing-transplanting methods.The diseases, insect pests and weeds in early and late rice with differentplowing-transplanting methods could effectively be controlled by appropriate pesticidesapplied during the early days of pest occurrence, and average10.00%and7.88%of theyields were increased, respectively. The study will provided a reference for the extension of control technology on diseases, insect pests and weeds of double-cropping rice in paddyfield production mechanization.2The localization field experiments with straw returning, straw burning ash returningand straw no-returning as the control for two years were conducted, Results showed that，under the same conditions of fertilizer and water management, there was not significantdifference among the sheath blight disease indexes of early and late rice with strawreturning, straw burning ash returning and straw no-returning in2012-2013. The curledleaf rates of the second generation of C. medinalis in early rice with straw returning in2012was20.3%, which was significantly higher than those with straw burning ashreturning and straw no-returning, while the curled leaf rates of the fifth generation in laterice was12.0%, which was significantly lower than those with straw no-returning. Thepopulation density of rice planthoppers in late rice with straw returning in2012was475heads/100clusters at full heading stage, which was not significantly different comparedwith straw no-returning, and1100heads/100clusters at milky stage, which wassignificantly higher than those with straw burning ash returning and straw no-returning.The population density of rice planthoppers in late rice with straw returning in2013was500heads/100clusters at full heading stage, which was not significantly lower than thatwith straw no-returning, and675heads/100clusters at milky stage, which was notsignificantly different compared with straw no-returning. There were3disposes in earlyand late paddy fields in2012-2013, which M. vaginalis and E. crusgalli were the dominantspecies. The weeds’ density with straw returning in early and late paddy fields was higherthan that with straw no-returning, and higher than that with straw burning ash returning inearly paddy field, equal to that with straw burning ash returning in late paddy field.Variance analysis indicated that the average yields of early and late rice in2012-2013wereincreased by8.2%and8.6%with straw returning compared with straw no-returning,respectively, and by5.9%and3.5%with straw burning ash returning, respectively. Theyield with straw returning was significantly increased under the conditions of equalnutrient. The occurrence of diseases, insect pests and weeds with straw returning could beeffectively controlled by applying pesticides, and rice yields were increased.3The toxicity of three biological fungicides on R. solani in the greenhouse and itsefficacy in the paddy field were assayed by the methods of mycelial growth rate and foliarspray, respectively. EC50values of Allicin and Zhongshengmycin on R. solani in thegreenhouse were29.10and29.03mg/L, respectively, and EC50values of Bacillus subtiliswere2.39×109active Bacillus/L. The efficacies of allicin6%EW at200-1200mg a.i./L,Zhongshengmycin3%at50~300mg a.i,/L and Bacillus subtilis1.0×1011active Bacillus/gWP at4.0×1011-1.5×1012active Bacillus/L against R. solani on the seventh and fourteenth day after the sprayed were above66%. Allicin, Zhongshengmycin andBacillus subtilis against R. solani are feasible.4The formulation of pymetrozine·pyraclostrobine45%FSC was developed with themethod of wet grinding process. Main adjuvants such as wetting-dispersing agent,membrane-forming agent, thickening anent as well as ant-freezing agent were optimized.After primary screening, the best determined formula was as follows: pymetrozine25%,pyraclostrobine45%, SP-SC32804%，NA2%, PVA0.1%, Xanthangum0.2%, ethyleneglycol4%, rhodamine0.5%, octanol0.5%and water43.7%. The product suspension ratewas over90%, the decomposition rate of the active ingredient was less than5%at(54±1)℃and (0±1)℃for14days. The indicators of the formula agreed fairly well withthe experimentally relevant determined standards.