A Study Of The Characteristics And Infection Of Leptosphaeria Biglobosa A1(Phoma Stem Canker)

The pathogen A1was isolated from the infected plants which collected from the oilseed rape crops in Anhui Province. Bases on the morphological identification, the pathogenicityexperiment and internal transcribed spacer (ITS) sequence analysis showed that the pathogen was identified as Leptosphaeria biglobosa. Following, we explored and confirmed the optimal growth and infection conditions of L. biglobosa A1. And on this basis, we made the conidia of L. biglobosa A1infect different oilseed rape varieties in order to test the disease resistance of them. Finally, by culturing the pathogen A1on PDA medium with different concentrations of fungicides, we tested the antibacterial activity of different fungicides on L. biglobosa A11. It provides the basis for the prevention and cure of phoma stem canker. The main results are as follows: 1. On PDA medium, the colonies of strain A1were white and villiform. The pycnidia was round or oblate and the conidium was transparent and colorless, containing two oilballs. It was verified that the conidia of pathogen A1were able to infect oilseed rape leaves and cause phoma leaf spots. The result of ITS sequence analysis showed that pathogen A1was highly similar to L.biglobosa.2. The strain A1was able to grow and sporulate at temperatures from5℃to35℃and pH value from4.0to10.0. The optimal growth temperature and pH value was25℃and neutral environment. The alternation of light and darkness was favorable for growth of the pathogen Al. Furthermore, The fungus A1could use many kinds of carbon and nitrogen sources. The best carbon and nitrogen sources were soluble starch and beef extract, respectively.3. Temperature and wetness duration had a great effect on the infection of L. biglobosa A1. The optimal conditions for the infection of L. biglobosa A1were a leaf wetness duration more than48h at21℃to24℃. Diease index decreased with decreasing wetness duration and decreasing or increasing temperature.4. The disease resistance of different oilseed rape varieties to L. biglobosa A1were significantly different. No high resistan varieries had been found in this experiment. And the oilseed rape variery of Ken You6was the highest resistant comparatively. Some varieries come from Inner Mongolia and Qinghai Province also showed higher resistance to L. biglobosa A1. 5. The antibacterial activity of different fungicides on L. biglobosa A1were differdent. The antibacterial activity of flusilazole was the most superior, and thiophanate-methyl has the worst bactericidal activity on L. biglobosa A1.