Pathogenicity Of Two Fusarium Species To Wheat&Maize And Sensitive Fungicide Screening

Fusarium graminearum and F.pseudograminearum are important pathogens to wheat,rice and maize—the three most important crops in the world.The fungus can infect many plant parts during the life cycle of the host and thus cause a range of diseases.F.graminearum and F.pseudograminearum can cause brown foot rot,crown rot,and scab(also known as ear or head blight)of wheat.and both stem rot and ear rot of maize.Interaction pathogenic of Fusarium graminearu isolated from corn and wheat are studied.Virulence of several fungicides to Fusarium graminearu in vitro and control effect on wheat scab in the field was measured.The results are as follows:(1)Maize and wheat have the typical symptoms of maize stalk rot and ear rot,wheat crown rot and head blight had been collected from Shangqiu,Zhoukou,Xuchang,Kaifeng,Sanmenxia,Wenxian in Henan Province.They were isolated using tissue isolation method.Morphological identification on the basis of the cultivation of the pathogen features and morphological characteristics and refer to Fusarium classification system.General primers of fungus ITS1/ITS4 and specific primers of F.graminearum Fg16NF/Fg16 NR is used molecular identification.Through comprehensive analysis of the result of the morphological identification and molecular identification.The results show that three pathogens isolated from the scab of wheat,two pathogens isolated from the crown rot of wheat,two pathogens isolated from corn stalk rot,two pathogens isolated from the ear rot of maize is F.graminearum.(2)Pathogenicity of pathogens was test in laboratory and field.Pathogenicity of Fusarium graminearum,2 isolates from wheat diseases head,2 isolates from wheat diseases stalk,2 isolates from corn diseased stalk,2 isolates from corn diseases head,1 F.pseudograminearum isolates from wheat diseases stalk,was studied,Though the interactive inoculation of F.graminearum and F.pseudograminearum on the healthy wheat and maize plants.These strains were divided into three groups based on the Relative index of pathogenic: strong pathogenicity,moderate pathogenicity and weak pathogenicity.The results show that,all tested strains were able to infect plants interactively.But the pathogenicity was significantly different.Strains on the testing to the pathogenicity of the scab of wheat showed that: All tested strains can induce the scab of wheat.Fg WX01?Fg SQ05?Fg SMX07?Fp QY10 was the strong pathogenicity strains,Fg FQ09 was the weak pathogenicity strain.The pathogenic of strains in two wheat cultivars,Aikang 58 and Lankao 198 were large different.Aikang 58 susceptible the disease,Lankao 198 resistance the disease.Strains on the testing to the pathogenicity of crown rot of wheat showed that: All tested strains can induce crown rot of wheat.Laboratory test and field test of pathogenic determination results are consistent.Strains infected the two wheat cultivars,Aikang 58 and Zhoumai 26,Fp QY10 was the strong pathogenicity strains,the rest strains are weaker than Fp QY10.Strains on the testing to the pathogenicity of corn stalk rot showed that: All tested strains can induce corn stalk rot.Laboratory test leading to the heavy incidence of the disease than the field test.The pathogenic of strains in two maize cultivars,Zhengdan 958 and Luoyu 4 is different.Zhengdan 958 susceptible the disease,Luoyu 4 resistance the disease.After inoculated with two maize cultivars,the incidence is consistent,the inoculated strains are differences compared with controls,but no obvious difference between different inoculated strains.Fg SMX07 was the strong pathogenicity strain,Fp QY10 was the weak pathogenicity strain.Strains on the testing to the pathogenicity of ear rot of maize showed that: All tested strains can induce ear rot of maize.The pathogenic of strains in two maize cultivars,Zhengdan 958 and Luoyu 4 is different.Zhengdan 958 susceptible the disease,In the maize varieties Zhengdan 958,there was eight strong pathogenicity strains including Fg WX01?Fg KF02?Fg XC04?Fg SQ05?Fg SQ06?Fg SMX07?Fg ZK08 and Fg FQ09,Fp QY10 was the weak pathogenicity strains.In the maize varieties Luoyu 4,there were two strong pathogenicity strains including Fg SQ06?Fg FQ09,five moderate pathogenicity strains including Fg WX01?Fg XC04?Fg SQ05?Fg SMX07?Fg ZK08.Fg KF02 and Fp QY10 was the weak pathogenicity strains.(3)Virulence of seven fungicides to Fusarium graminearum in vitro on wheat scab were measured.The results showed that JS399-19(2-cyano-3-amino-3-phenylacrylic acetate)and carbendazim had stronger inhibition to Fusarium graminearu,EC50 was 0.23?g/ml and 0.25?g/ml,respectively.EC50 of Tebuconazole was 0.54?g/ml.The inhibition of difenoconazole and thiophonate-methyl lowed obviously,EC50 was 2.56?g/ml and 4.43?g/ml.Triadimefon and azoxystrobin have no obvious inhibition to Fusarium graminearu,EC50 was 17.47?g/ml and 1434.30?g/ml.The influence of the 25% JS399-19 and 50% carbendazim on conidial germination of Fusasiurn graminearum were determined.The results showed that,JS399-19 and carbendazim could decreased the speed of conidial germination of Fusarium graminearum,strongly inhibited the germtube growth of the conidia,and affected the conidia germination by causing the ratio of the tubes germinated from the basal and that from the middh parts of the conidia increased.Moreover,fungicides could cause abnormality of conidia and the tubes of the strains,by inducing the conidia to swell,and inducing the tubes to swell and contort,respectively.(4)The effect of the experimental results show that the control effect was 83.84% using 25% JS399-19 500× spraying in the initial flowering stage,and thousand kemel weight of wheat increased 72.29% than that of contrast.The control effect of carbendazim was 79.43%,and thousand kernel weight increased 74.87% than that of contrast.The control effect and yield increasing of JS399-19 and carbendazim were significantly higher than thiophonate-methyl,triadimefon,tebuconazole,difenoconazole and azoxystrobin.