Beet curly top disease (Curtoviruses) in spinach and table beets inArizona

Beet curly top disease is caused by Curtoviruses, a group of viruses transmitted by the beet leafhopper (Circulifer tenellus). It occurs in many different plants in Arizona including tomato, pepper, cucurbits, spinach, and beets. The viruses also are differentially hosted by many other plants including alfalfa (Nischwitz and Olsen, 2010) and many weeds (Creamer et al. 1996; Lam et al. 2009). In the USA, the Curtovirus group currently consists of seven viruses – Beet curly top virus (BCTV), Beet mild curly top virus (BMCTV), Beet severe curly top virus (BSCTV), Pepper curly top virus (PCTV), Pepper yellow dwarf virus (PYDV), Spinach curly top virus (SCTV) and Horseradish curly top virus (HrCTV). When more than one of these viruses infects a plant, they readily exchange genes and recombine, so variation in their incidence is common. Curtoviruses and their only known vector, the beet leafhopper, are native to the western United States. In recent years, Curtoviruses have resulted in significant losses in table beet and spinach plantings in Arizona. The Curtoviruses associated with spinach and beets in Arizona during 2009-2010 are identified in this bulletin along with other non-symptomatic hosts that harbor the viruses. Knowledge of host range and location are useful for efficacious weed control and reduction in disease severity