Effects Of Combined Application Of Biocontrol Bacteria And Fungicides On Pathogenic Bacteria Of Major Rice Diseases

Rice is an important food crop in C hina,and various diseases of rice seriously affect the output of grain.Fungicides can effectively inhibit the occurrence of various diseases of rice,but long-term large use of fungicides will cause environmental pollut ion,drug resistance.The biocontrol bacteria have little impact on the environment ?diseases hardly to resistant,and have good application prospects.However,biocontrol bacteria are slow to take effect,and their use is limited due to the large environmental impact and other unfavorable factors.The ideal measure is the combined use of chemical agents and biocontrol agents to achieve the control effect and at the same time slow down the development of pesticide resistance.In this experiment,the biocontrol Trichoderma and Bacillus were used in combination with fungicides,to study their inhibitory effects on the growth of the pathogenic fungi of the main diseases of rice,and to explore the inhibitory effects of the combined use of biocontrol bacteria a nd fungicides on rice pathogens.1.After indoor toxicity testing,the inhibitory effects of the four chemical agents against the pathogen of rice bakanae were boscalid < fludioxonil < cyanostrobin < epoxiconazole.The confrontation culture method was used to determine the inhibitory effect of three kinds of Trichoderma on rice bakanae pathogen.Trichoderma viride > Trichoderma longibrachia >Trichoderma harzianum.The colony growth rate method was used to determine the compatibility of the fungicide,Trichoderma and C yanoxystrobin have good compatibility with the three Trichoderma.The combined use of cyanenoxystrobin and boscalid and three kinds of Trichoderma has synergistic and additive effects on the inhibition of rice bakanae pathogens.Among them,the combined use of cyanostrobin and Trichoderma viride has a significant synergistic effect.2.Using the mycelial growth rate method and the confrontation culture method to determine the susceptibility of rice sheath blight bacteria.Studies have shown that the in hibitory effects of 4 chemical agents on Rhizoctonia solani are azoxystrobin>propiconazole>epiconazole>zincthiazole.Inhibitory effects of three kinds of Trichoderma on rice sheath blight fungus are Trichoderma longibrachiatum>Trichoderma viride>Trichoder ma harzianum.Azoxystrobin and zinc thiazole have good compatibility with three kinds of Trichoderma.The combined use of azoxystrobin and Trichoderma longibrachiatum has a better inhibitory effect on rice sheath blight and has synergistic and additive effects.3.The hypha growth rate method was used to determine the indoor virulence and inhibitory effects of 4 kinds of chemical agents and 2 kinds of Bacillus on pathogen of Bipolaris oryzae.The results showed that the inhibitory effects of four chemical agents were kresoxim-methy >etiticin > Bordeaux solution > tricyclazole.The inhibitory effect of Bacillus subtilis on the pathogen of Bipolaris oryzae is stronger than that of Bacillus licheniformis.Kresoxim-methyl and Bordeaux mixture have the best compatibility with the two Bacillus species.The combined use of Kresoxim-methyl and Bacillus subtilis has the best inhibitory effect on the pathogen of rice flax leaf spot.4.The indoor inhibitory effects of four chemical agents and two Bacillus suspensions on the pathogen of Magnaporthe oryzae by using mycelium growth rate method.The results showed that propiconazole has the highest toxicity,followed by kresoxim-methyl and kasugamycin,and tricyclazole.The inhibitory effect of Bacillus subtilis suspension to Magnaporthe oryzae was better than that of Bacillus licheniformis suspension.Kresoxim-methyl and kasugamycin have the best compatibility with two kinds of Bacillus,and their combined use has synergistic effect on the inhibition of Magnaporthe oryzae.Among them,the combined use of Kresoxim-methyl and Bacillus subtilis has the most obvious inhibitory effect.