Curly top is a viral disease that affects many crops. This disease causes plants to become smaller in size, have shriveled petals and leaves, and are twisted and pulled out of shape. They are often caused by curtoviruses (genus Curtovirus), members of the virus family Geminiviridae. This disease is important in western United States, such as California, Utah, Washington, and Idaho. Curly top is characterized by stunting of the plant and deformation of leaves and fruit. The petioles and blades of the leaves curl, twist, and become discolored. Beet curly top virus causes curly top disease in beets and is carried by the beet leafhopper (Circulifer tenellus) throughout arid and semi-arid locations. The term curly top virus often refers to this specific virus. It can also cause curly top in tomatoes, beans, cucurbits, and other crops. This disease can be reduced if plants are planted in the shade because the beet leafhoppers and other insects like to feed on these plants in the sun. Curly top disease in spinach can be caused by Beet curly top virus, Pepper curly top virus, or Spinach curly top virus. Other curly top curtoviruses include Beet severe curly top virus, Beet mild curly top virus, and Horseradish curly top virus. Turnip curly top virus may also be a species of Curtovirus. Discovery of Curly Top Knowledge of curly top's early history in the United States is limited owing to its sharing similar symptoms with other diseases and disorders. According to C. O. Townsend, George G. Hedgecock with the USDA reported that, on several occasions before 1888, he observed damaging outbreaks of a disease presumed to be curly top from garden beets in Nebraska. In 1897, George Austin stated that the Utah Sugar Company suffered overwhelming losses near Lehi, UT from an unidentified disorder resembling curly top. The disease also was noticed in California in the 1890s, with severe losses reported from the newly emerging sugar beet industry in that state. By 1900, it had been noted throughout all western states where sugar beets were grown, suggesting it was already widely distributed before it was first recognized or studied as a distinct disease. This hypothesis is conceivable because the first description of the beet leafhopper on sugar beets was made from the western slope of Colorado in 1895 by C. P. Gillette and C. F. Baker. As early as 1905, E. D. Ball suspected the