Abstract: 【Objective】 Allantophomoides carotae is the firstly-reported new strain by the author in China. It can cause the Carrot Spotted Withering Disease, thus makes great damage in the course of the production process. 【Method】The effects of temperature, pH, illumination and the sources of nitrogen and carbon on the growth of hypha, the emergence and germination of conidiospore of Allantophomoides carotae were studied.【Result】 The most suitable range of temperature is 10-30℃ and the optimum temperature is 25℃ for hypha growth, the lethal temperature is 45℃(within 30 min) or 50℃(within 10 min) for conidiospore and 65℃(within 30 min) for hypha. Within the pH range of 4-12, the hypha could grow and produce conidiospore, and the conidiospore could germinate. The optimum pH is 8-10 for hypha growth and 7-9 for conidiospore germination; The hypha could not grow on the culture medium which nitrogen source comes from urea and asparagines, but it could grow fast and produce more conidiospore on the culture medium which carbon source comes from maltose, glucose and lactose, and nitrogen source come from glycine, histidiane and peptone. The effect of illumination on Allantophomoides carotae was insignificance to the growth hypha and the emergence and germination of conidiospore. 【Conclusion】The study of this article tentatively made a research of the biological characteristics of this pathogenic bacteria. It provides a theoretical basis for the prevention and control of this disease.

Key words: Allantophomoides carotae, Biological Features, carrot