In summary, all major areas of Thailand (Fig. 3) are infected by strains of SCWL-phytoplasma causing yellow midrib symptoms or white leaf symptoms. The often observed yellow midrib symptoms in Thailand sugarcane plantations may therefore stem from either Sugarcane yellow leaf virus infection (Lehrer et al. 2008) or from mild stages of white leaf symptoms, but not from Western X disease phytoplasma, which caused Sugarcane leaf yellows in Africa and Cuba (Cronje et al. 1998; Arocha et al. 1999). The results of this study are more than of regional interest, because the wide distribution of SCWL-phytoplasma in Thailand suggests that sugarcane plantations in all Southeast Asia are infected by phytoplasma. Indeed, reports from India and Sri Lanka indicated phytoplasma-infection of the SCWLP or SCGSP type (Chona et al. 1960; Ariyarathna et al. 2007).