Abstract: Asingle cotton plant grown in a pot was inoculated with the same amount ofVerticilliumdahliaecombining with treatment withBacillussubtilisand soil sample of disease nursery to explore the relationship between theV.dahliaecontent in the potted soil at different time points and the disease degree of the individual plants. The organism DNA in the soil was extracted，andV.dahliaecontent in soil was analyzed by qPCR with specific primers. The pathogens content in soil was further verified by colony counting of washing solution from the potted soil. The results showed that significant differences inV.dahliaecontent in the potted soil inoculated with equal amount of fungi at different time points were shown. And at the same time point，there was a significant difference in the change of the fungi content in the different potted soils，especially in the later stage of time points. Then covariance analysis showed that there was a significant positive correlation between the disease degree of a single potted plant and theV.dahliaecontent in the soil. The treatment ofB.subtilisand the analysis ofV.dahliaecontent in the disease nursery soil further confirmed that the disease degree of a single plant was positively related to the fungi content in the soil. In general，the results provide theoretical guidance for the control of cotton Verticillium wilt.

Key words: cotton, Verticillium wilt, Verticilliumdahliae, soil fungal content, disease degree