Research On Integrated Control Of Rice Blast In Donggang Of Liaoning

Rice Blast is a kind of serious diseases which has significant effect on the rice production and causes great loss on the rice yield every year. In order to clarify the kinds, symptoms of damages and control measures of rice blast in Donggang City of Liaoning Province, this paper carried out the research on indoor toxicity measurement of the blast control agents, chemical control of rice blast in the fields, differences of diseases resistance on rice blast between popular rice cultivars in Donggang City, impact of different cultivation practices on the rice blast, and then proposed the integrated control measures including using high efficient agents and good resistant species, strengthening fertilizer and water management and combining the prevention and control of diseases. The conclusions are as follows:1. Indoor toxicity measurement of the blast control agentsWe have selected 9 different germicides that have inhibitory actions on the growth of Magnaporthe grisea mycelial and spore and test their indoor toxicity measurement. The test results show that the inhibitory actions of different agents on the above two growth are quite different. Among different agents, Shi Bao Ke has the best inhibitory action on spore germination of M. grisea EC50=5.29mg/L while tricyclazole are the worst. In regard to the inhibitory actions of two biological agents Haomide and Kasugamycin, Haomide is better, EC50=122.4mg/L.2. Chemical control of rice blast in the fieldsWe have selected 4 germicides to set up the plot trials to test chemical control of rice blast in the farm of Donggang area. The survey of control efficiency shows that four fungicides have obvious effects on rice blast and can reduce the incidence and degree of rice blast significantly. They also can improve the rice grain weight and increase rice biomass.25% azoxystrobin SC is the best one and the minimum control efficiency was above 72% and can be up to 83% at the most.75% tricyclazole WP, 2% kasugamycin WP were the second and the highest control efficiency was 80% while the control effect of the lowest dose was still above 74%. So all of them may be alternatively used in the field control of rice blast.3. Diseases resistance on rice blast between popular rice cultivars in Donggang CityWe have selected 17 popular rice cultivars in Donggang area to take the screening trials of rice blast resistance in 3 test plots. The results show that there were obvious differences of resistance on rice leaf blast and panicle blast between the popular cultivars. The locally bred varieties in Donggang area, Donggang 8, Dongsi 15, Dongyu 129 and Gongyu 6 have good resistance to rice blast.4. Control research of different cultivation practices on the rice blastWe have selected 4 test plots in Donggang area and studied the effect on rice blast occurrence under different sowing dates, different fertilization levels when other conditions remain the same. The results in different sowing times and different transplanting times have shown that occurrence degree of rice blast was inconsistent and there was no obvious regularity observed under the conditions of temperature, humidity, illumination in year of 2009 and without agentia. The results under different fertilizer levels have shown that leaf blast and panicle blast in the areas applying 50% more fertilizer were more serious than the areas applying 20% more,10% more fertilizer and there were no significant difference between the area applying 20% more,10% more fertilizer and the areas with normal fertilizer application. In conclusion, the results show that three chemical fungicides myclobutanil, Daoshou and ShiBaoKe and biological fungicide HaoMiDe have good inhibitory action on spore germination and mycelial growth of rice blast fungus; azoxystrobin Ester, tricyclazole, kasugamycin, ShiBaoKe and so on could control the occurrence of rice blast when applying once each in both rice booting end and full heading stage. Species such as Donggang No.8 had physiological conditions of rice blast resistance in the plant type, growing period and other aspects, and shows good growth and yield adaptability, so it was suitable to be promoted in Donggang rice cultivation area. But species rotation is required every year. There are no obvious rule observed in different nursery and planting time in prevention of rice blast, but it is observed that rice blast had large incidence trend when increasing fertilizer application to a certain dose while there is no significant incidence trend when fertilizer application was limited within a certain range.