Biological characteristics and host range of the pathogen causing brown spot on Ligustrum lucidum Ait.

【Objective】 This study was aimed to understand the effects of environmental factors on the growth of Neofusicoccum parvum and clarify its pathogenicity to different plant species,so as to provide a theoretical basis for the effective control of the disease.【Method】 The N. parvum NPGY-1 of Ligustrum lucidum Ait. brown spot identified in previous studies was used as test strain,and the effects of temperature,pH,carbon and nitrogen sources on the growth of the pathogen were measured by colony growth rate method. To determine the host range,the pathogenicity of the pathogen to different kinds of plants was determined by in vitro leaf inoculation.【Result】 The results of biological characteristic tests showed that the optimum growth temperature and p H of the pathogen were 28℃ and 6.0,the expanded diameters of colonies cultured on PDA medium for 3 d were 50.7 and 62.9 mm,respectively. The optimum carbon sources were sucrose,glucose and mannitol,and the optimum nitrogen sources were glycine and(NH₄)₂SO₄. Based on the pathogenicity tests of 73 plant species coverring 49 families,a total of 66 plant species belonging to 44 families showed symptoms on their inoculated leaves at various degrees. Seven plant species【Abelmoschus Manihot(L.)Medicus,Hibiscus syriacus L.,Mentha canadensis Linnaeus,Perilla frutescens(L.)Britt.,Pittosporum tobira(Thunb.)Ait.,Trichosanthes kirilowii Maxim. and Viola verecund A. Gray】 covering five families(Cucurbitaceae,Malvaceae,Labiatae,Pittosporaceae and Violaceae)were symptomless during the tests.【Conclusion】 N. parvum,the pathogen causing the brown spot disease of L. lucidum,has strong adaptability to the environment and has potential pathogenicity to many plant species. In landscaping plant configuration,plants with different resistance levels should be selected to match,which is conducive to reducing the occurrence and prevalence of the disease.