INCIDENCE AND DISTRIBUTION OF 6 VIRUSES INFECTING TAMARILLO (CYPHOMANDRA-BETACEA) IN NEW-ZEALAND

The distribution and incidence of six viruses infecting tamarillo in New Zealand was investigated in 12 tamarillo orchards from the four major growing districts-Bay of Islands, Auckland, Bay of Plenty, and Poverty Bay. Virus infections were assayed by mechanical inoculation to indicator plants, dot blot analysis, and enzyme-linked immunosorbent assay (ELISA). Tamarillo mosaic potyvirus (TaMV) was found to be widespread, usually occurring in 100% of plants. The incidence of TaMV infection was lower (0-40%) in two orchards that were geographically isolated from any other tamarillo plantations. Potato aucuba mosaic potexvirus (PAMV) was detected in all growing regions, typically infecting 40-100% of plants. In the Bay of Plenty and Poverty Bay districts, cucumber mosaic cucumovirus (CMV; 30-90% infection), alfalfa mosaic virus (AIMV; 10-80% infection), and tomato spotted wilt tospovirus (TSWV; 0-90%) were also detected. These viruses were not found in the other districts. When compared to previous studies, these results show that TaMV is still the most widespread virus infecting tamarillo, but that in two major growing districts, AlMV and TSWV are now established at high levels. CMV is no longer present in all tamarillo-growing districts, being confined to the two most southern growing regions analysed in this survey. In contrast, PAMV is now present in all tamarillo-growing regions. Arabis mosaic nepovirus was not detected in this survey.