The Combined Inhibitory Effect Of Fungicides And Wheat Spike Endophytic Fungi On Fusarium Graminearum

Wheat is the second largest food crop in China,and wheat scab has a serious impact on wheat quality.At present,no disease-resistant varieties have been found in production,and wheat scab has developed resistance to carbendazim,a commonly used fungicide in China,and the control effects of fludioxonil and tebuconazole have begun to weaken.In response to the goal of“reduction and increase efficiency”of pesticides proposed by the Ministry of Agriculture,this paper studied the morphological toxicology of Fusarium graminearum from three fungicides:fludioxonil,carbendazim and tebuconazole;healthy wheat from various regions of Henan Province Endophytic fungus were isolated from the ear,and endophytic fungi were inhibited from F.graminearum.Finally,the endophytic fungal fermentation broth was combined with fungicide to determine the control effect against F.graminearum.In order to achieve the purpose of reducing the amount of pesticides used and improving the control effect of pesticides.The main results are as follows:（1）All three fungicides can effectively inhibit the mycelial growth,sporulation,spore germination and germ tube elongation of F.graminearum.In contrast,fludioxonil had the best control effect on wheat scab,followed by tebuconazole,and carbendazim had the weakest control effect on wheat scab.（2）95 endophytic fungi were isolated from the four parts of healthy wheat spike by the method of tissue separation,and 17 strains of F.graminearum were screened by plate method.Antagonistic endophytic fungi,numbered ML-3,WF-16,WF-17,WF-19,YK-14,YK-15,YK-16,YK-18,YK-20,ZJ-7,ZJ-13,ZJ-14,ZJ-15,ZJ-16,ZKTK-11,ZKTK-13,ZKTK-17.（3）Morphological identification according to"Chinese fungal"Penicillium coil and Aspergillus coil,wherein ZKTK-17 was identified as Aspergillus clavatus;ML-3,WF-16 and YK-20 was identified as Penicillium oxalicum;ZJ-7,ZJ-13,ZJ-14,ZJ-16and ZJ-15 were identified as Penicillium citrinum;WF-19,YK-14,YK-15,YK-16 and YK-18 were identified as Penicillium corylophilum;WF-17,ZKTK-11 and ZKTK-13were identified as Penicillium expansum.（4）Determination of the inhibitory effect of 17 endophytic fungal fermentation products on F.graminearum,wherein the EC₅₀0 value for mycelial growth ranged from0.1218 to 27.3562 g/mL.Most strains inhibited spore germination by more than 90%.（5）The sensitivity of endophytic fungi to fungicides was determined.The endophytic fungi which are least sensitive to fludioxonil are WF-16 and ZKTK-17.The inhibitory effect of carbendazim on endophytic fungi is greater than that on F.graminearum,inhibiting the elongation of germline tube of endophytic fungi and causing malformation of germ tube.Therefore,carbendazim combined with endophytic fungi to control wheat scab The application value is lower.The endophytic fungi that are least sensitive to tebuconazole are WF-16 and WF-17.The endophytic fungi that are least sensitive to cyanide are ML-3 and WF-17.（6）The fungicide is mixed with the endophytic fungus fermentation liquid to obtain a better ratio of combined control effect.The addition effect of cyanide and ML-3 fermentation liquid in the ratio of 6:4 was the most obvious,and the toxicity ratio reached 1.25.the toxicity ratio of tebuconazole to WF-16 fermentation broth is2:8,and the additive ratio is second.In this study,the morphological toxicology of the fungicide against F.graminearum was studied.Endophytic fungi which inhibited F.graminearum were screened,and the fermentation liquid and fungicide were combined with the interior of F.graminearum.The research on inhibition has reached the goal of reducing the amount of pesticides used,and opened up new ideas for biological control,laying a theoretical foundation for biological control.