|Abstract||Plant root systems play many key roles including nutrients and water uptake, interface with soil microorganisms and resistance to lodging. Unfortunately, as for any other crop, large and systematic studies of sugarcane root systems have always been hampered by the opaque and solid nature of the soil. In recent years, methods for efficient extraction of DNA from soil and for species-specific DNA amplification have been developed. Such tools could be adapted for sugarcane and have the potential to greatly improve root phenotyping and health diagnostic capability in sugarcane. In this report, we present a fast and efficient method for the quantification of live sugarcane root mass in soil samples. First we demonstrated that this test is sensitive and specific to sugarcane. Then we established a universal calibration for the test to convert root DNA quantity to live root mass. Finally we validated our test on field samples and used it to answer the question of the fate of the root system after harvest. There we demonstrated that, two weeks after harvest, the sugarcane roots are still alive. It raises the question of the role that the former root system plays in the performance of the following crop and demonstrates how this test can be used to answer research question or to monitor crop root health.