Study On Indoor Morbidity Condition Of Soybean Rust And Screening Of Its Control Agents

The global climate is gradually warming.Soybean rust also spreads from low latitudes to high latitudes,and the area of disease has increased significantly.The damage of rust to soybean and the loss of yield caused by rust are one of the most important issues for soybean producers.Therefore,domestic and foreign countries have strengthened the cultivation of soybean rust-resistant varieties and new bactericide research.However,field trials of soybean rust are limited by regional and seasonal factors,restricting the progress of the above studies.On this basis,in this paper,three aspects of indoor soybean rust disease conditions,isolation of diseased leaves,and screening of indoor control agents were studied.The results are as follows:1.Using indoor soybean seedlings inoculated with urediospore,the effects of soybean variety and leaf age,inoculation concentration of urediospore suspension,culture temperature and humidity,and different inoculation methods on the incidence of indoor soybean rust were studied.The results showed that the incidence of soybean rust in 7 varieties was more than59%,all susceptible to disease;the highest incidence of leaf rust in 6-leaf stage was 62%;tthe highest incidence of leaf rust in soybean rust was 83.7% at the four inoculum concentrations were 5×109spore/m L;the highest incidence of leaf rust in soybean rust was63.0% at three culture temperatures at 25°C;The highest incidence rate of leaf was 76.67% at the four cultivating humidity were 100% relative humidity for soybean rust;There was no significant difference in the incidence of soybean rust between the spraying method and the smearing method.and they were all above 60.2%.2.In vitro observation of the urediospore germination test showed that: With the increase of treatment temperature,the germination rate of urediospore increased,25 °C is the optimum temperature for spore germination.The temperature at the time of germination was the same.With the extension of germination time,the germination rate of urediospore increased.In vitro,the germination rate of the diseased leaves kept at the same temperature and the spores germination rate decreased with the extension of the leaf preservation time;the soybean diseased leaves stored at 4 °C for 45 days,the urediospore had lost their ability to germinate.The germination rate of soybean rust urediospore stored at-20°C and-80°C increased with the extension of storage time,but the germination rate was still detected at 90 days after storage.Soybean rust was inoculated after 90 days of storage at different temperatures.Soybean rust failed to infect soybeans under 4°C storage conditions,causing rust.Under the-20 °C and-80 °C conditions of preservation,soybean rust still have the ability to disease,leaf incidence were 40.57% and 49.33%.3.The results of six germicides on the germination of soybean rust urediospore and the protection and treatment of soybean rust showed that six fungicides had strong inhibitory effects on the germination of rust urediospore.Among them,difenoconazole had the strongest inhibitory effect on the germination of soybean urediospore,and EC50 value was 7.3283?g/m L;followed by azoxystrobin,flusilazole,mancozeb,triadimefon and chlorothalonil.The best protection against soybean rust was azoxystrobin and flusilazole,.The best treatment effect was azoxystrobin and the control efficacy was 100%.