 The discovery of curly top transmission by leafhoppers strongly suggested a viral etiology; however, the pathogen’s identity was not formally established until the 1970s.The typically low concentration of virus particles within infected plants made isolation and purification difficult.Therefore, it was not until 1974 that a virus was formally proven to be the cause of the disease, after advancements in virus purification were made and the characteristic twinned particles of geminiviruses were observed with electron microscopy.