Sugarcane yellow leaf symptomatic plants in Thailand are infected by white leaf phytoplasma, not by leaf yellows phytoplasma

Yellow midribs of sugarcane leaves are a typical symptom of Leaf yellows which was found in Africa, Cuba and India, caused by Western-X disease phytoplasma. Yellow midrib symptoms were found in sugarcane in Thailand, too. Leaves with yellow midrib symptoms were collected in plantations in Northeast, Southeast and Central Thailand and tested for phytoplasma. The symptomatic leaves and often also non-symptomatic, green leaves of sugarcane from all three regions contained phytoplasma of the Sugarcane white leaf phytoplasma type, which is a member of the Rice yellow dwarf group. No Western-X disease phytoplasma was found in the samples. It is concluded that yellow midrib symptoms in Thailand sugarcane are not caused by the Leaf yellows phytoplasma, but are an early symptomatic stage of White leaf phytoplasma. White leaf phytoplasma is not only confined to the Northeast of Thailand from where it had been previously reported, but is also prevalent in the other sugarcane regions in Thailand, which calls for a simple, rigorous identification of infected seed cane to eradicate the disease.