Variety resistance ratings are provided by Sugar Research Australia for a number for sugarcane diseases through SPIDNet. These diseases rely on resistance as little can be done in regard to their management. However, for ratoon stunting disease (RSD), one of the most important diseases in the Australian industry, this has not been the case in recent years. For RSD, the term “resistance” is somewhat misleading and can impart a false sense of security if viewed as for other diseases. All known varieties can acquire RSD, which can lead to yield losses and also in turn act as an infection source. Enzyme-linked immunoassays (EB-EIA) were previously used to estimate Leifsonia xyli subsp. xyli (Lxx) bacteria titres and to assign a resistance rating. Quantitative polymerase chain reaction (qPCR) offers a more specific and sensitive method of detecting Lxx. The qPCR method can also provide more accurate estimates of Lxx titre. This study compared the leaf sheath biopsy (LSB) sample type in the plant crop and the xylem-extract sample type in plant and first-ratoon crops with the aim of developing a variety rating method.