Study On Infection Period Of Pathogen And Cultivars Resistance To Corn Stalk Rot

To study the Infection Period of Pathogen of Fusarium graminearum and Fusarium verticillium, we use Xundan20 and Luoyu2 which were susceptible to corn stalk rot for field trials. To analyse the separation frequency and testing frequency of these two kinds of pathogen,we adopt conventional tissue isolation and molecular detection methods . The results show that the Fusarium graminearum and Fusarium verticillium have infected corn root in seven leaves stage , and with the growth of corn the frequency of separation and detection increase; Fusarium graminearum and Fusarium verticillium were not separated and deteted in stem base until the jointing stage ,thus we deduce that Fusarium graminearum and Fusarium verticillium invade the corn gradually from the roots of corn to stem base, and with the growth of corn the frequency of separation and detection increase.With the same conventional tissue isolation and molecular detection methods for analysis of Fusarium graminearum’s separation and detection frequency, Potted plants Xundan20 which were inoculated with Fusarium graminearum were researched. The results show that when the corn were inoculated with Fusarium graminearum, pathogenic bacteria can be separated and detected in three leaves stage ,while pathogenic bacteria can’t be separated and detected in stem base until pollen stage. This indicate that Fusarium graminearum may infect roots in three leaves stage, and expand upward gradually, intrusive stem base in pollination period, this result is consistent with the conclusions that Fusarium graminearum invade corn from roots. Separation frequency of Fusarium graminearum in the roots is significantly higher than the stem base, you can learn that Fusarium graminearum may mainly invade corn’s root, and expand upward from the roots gradually.Through detecting the sensitivity of Fusarium graminearum’s specific primer and Fusarium Verticillium’s specific primer, we could reach the conclusion that the detection sensitivity of Fg16F/Fg16R is about 0.33ng/ul and the detection sensitivity of Fu4/Fu5 is about 0.57ng/μl. By making onset investigation testse on different varieties of potted plants inoculated with Pythium sp.and Fusarium graminearum in seedling stage , we identified that there were 6 kinds of varieties which are resistance to both of these bacterias, including Jinrong99, Zhengdan2201, Qindan5, Zhengdan22, Qiangsheng1, Luoyu4.By making anti-stem rot disease identification tests on different varieties of corn which were perennial planted in disease nursery ,the results indicate that among the 55 varieties in the identification,29 varieties have performance resistance to corn stalk rot, accounted for 52.7%, including Chaoyu1, Jinyu6, Jinyu8, Jinyu216, Luodan248, Nongda108, Qiangsheng1, Qunying8, et al. The results show that among the varieties which are popularizing or will be popularizing, there is a high percentage of anti-disease varieties,it is easy for us to choose anti-disease varieties reasonably according to the occurrence condition of stem-rot disease in maize in different areas.To sum up, Fusarium graminearum infect roots in three leaves stage, invade stem base in pollen stage, and the infection rate of Fusarium graminearum in corn root is rather slow in seven leaves stage and jointing stage, it has not a progressive growth until in tasseling stage and Fusarium graminearum may mainly be root-infection. Fusarium verticillium can invade corn roots before seven leaves stage, infect stem base in jointing stage. Fusarium graminearum in corn roots is advantage strains, and Fusarium verticillium in stem base is the dominant strains. Zhengdan2201, Jinrong99, Qiangsheng1, the identification of natural morbidity in field and potted in the field have shown good ant-disease performance. It is the foundation of comprehensive prevention and control to make use of varieties with disease resistance to prevent and control the stalk rot disease of corn. Understanding the anti-disease status of varieties which are popularizing or will be popularizing, current production and promotion or about cultivars resistance status, is of great significance for our action of using resistant varieties to prevent and predict the occurrence of diseases, it also provides reference information for producers and breeders.