Nearly all plants from Southeast, Northeast and Central Thailand were infected by phytoplasma of the Sugarcane white leaf phytoplasma, i.e. the Rice yellow dwarf type, irrespective of whether the plants were symptomatic or not. The titre of phytoplasma varied strongly, those plantswhich were strongly symptomatic of white leaf or grassy shoot always had a high phytoplasma-titre, whereas some samples, which clearly produced nPCR-amplicons, did not give a product in qPCR above detection limit. Phytoplasma titres were in these cases obviously too low for a one-step PCR such as qPCR. In some samples only one of the nPCR tests produced a product, which indicated that the phytoplasma strains in Northeast Thailand (Khon Kaen) and Central Thailand (Suphanburi) were different, whereas the Chonburi strain was similar or identical to the northeastern strain. The phytoplasma types in sugarcane show 1–3 bases difference inside a 210 bp stretch of the 16S-23SITS, which may possibly affect the binding of primers. White leaf symptomatic crosses of sugarcane with Erianthus had a mixed infection, namely a 3 bp different strain from that in sugarcane besides the SCWL-phytoplasma. The different sensitivities of phytoplasma strains to nPCR primers and qPCR may possibly lie in these small sequence differences, some possibly also outside of the 210 bp stretch. The phytoplasma strains in white leaf symptomatic weed grasses also belong to the Rice yellow dwarf group, but fall into another subgroup than SCWL phytoplasma (Sakuanrungsirikul et al. 2012).