During the 2005 growing season, widespread virus-like symptoms were observed in pepper (Capsicum annuum) fields in north-central Mexico. Early in the season, plants were chlorotic and stunted with thickened, elongated leaves. From mid to late season, the affected plants showed severe yellowing, upwardly rolled, small leaves, and a few deformed fruits. Symptoms were similar to those described for curtoviruses in pepper (1). The leafhopper vector of curtoviruses, Circulifer tenellus, was first reported in the area in 1953 (3) (its presence was confirmed again in January 2008). Pepper fields were sampled in the states of Aguascalientes and Zacatecas, and five symptomatic plants from Zacatecas tested positive for the presence of curtoviruses by PCR using primers to the coat protein (CP) coding region (2). PCR amplicons from three samples of Ancho and Mirasol pepper types from Zacatecas, which also tested positive by PCR using the rep coding region (2), were sequenced and compared with reported curtoviruses. The samples showed 91% identity with the CP coding region and 93% identity with the rep coding region of Beet mild curly top virus (formerly the Worland strain). A survey of pepper fields from Aguascalientes and Zacatecas based on symptomatic plants was conducted from July to August of 2005. Forty-three fields of different types of pepper, including those growing under mulch and drip irrigation, were surveyed. Twenty-five plants in each of five contiguous rows were inspected for the symptoms described above. Disease symptoms were noted in Mirasol, Ancho, Pasilla, and Guajillo pepper types, and the average disease incidence was 9.87% (range: 1.6 to 48%), 15.2% (range: 6.4 to 25.6%), 7.85% (range: 2.4 to 15.2%), and 20.8% (range: 8 to 33.6%), respectively. To our knowledge, this is the first report of curtovirus infection of chile pepper in this region of Mexico. The moderate level of curtovirus infection found here suggests the need to initiate management strategies for this disease.
References: (1) L. L. Black et al. Page 98 in: Pepper Diseases. A Field Guide. AVRDC, Taiwan, 1991. (2) R. Creamer et al. Plant Dis. 89:480, 2005. (3) D. A. Young and N. W. Frazier. Hilgardia 23:25, 1954.
