Studies on strawberry pallidosis disease
Strawberry pallidosis disease was first recognized in Australia and the USA in 1957, but is considered indigenous to North America (infected Australian plants had been imported from the USA). Strawberry pallidosis does not occur in the EPPO region. Strawberry pallidosis is graft-transmissible and induces symptoms on Fragaria virginiana (‘UC-10’, ‘UC-11’) but not on F. vesca indicators. In most commercial cultivars, pallidosis remains latent. However, since 2000, decline symptoms have been observed in strawberries along the west coast of North America. It was suggested that pallidosis might play a role in this decline.
In earlier studies, it has been found that two viruses belonging to the genus Crinivirus, were associated with pallidosis disease: Beet pseudo yellows virus (BPYV) and Strawberry pallidosis-associated virus (SPaV). Further studies have showed that SPaV is transmitted by Trialeurodes vaporariorum, but not by T. abutilonea and Bemisia tabaci. Pollen or seed transmission was not observed for SPaV. Testing for SPaV and BPYV was carried out in strawberry nurseries and fields of North America (USA: California, Florida, Oregon, Washington; Canada: British Columbia) to estimate the presence of both viruses and their importance in strawberry decline. Results showed that infection rates as high as 90% for SPaV and 60% for BPYV were observed when plants exhibiting decline symptoms were tested. California was the most affected state. In some areas (Washington, British Columbia), SPaV and BPYV were not detected in declining plants. Lower rates of infection of SPaV and BPYV were found in regions where whiteflies were absent or found in low numbers. Both viruses were detected in nurseries and efforts are being made to eliminate them from strawberry planting material. Research will continue to develop integrated pest management systems to minimize the incidence of the disease in areas where it still occurs.
Tzanetakis IE, Wintermantel WM, Cortez AA, Barnes JE, Barrett SM, Bolda MP, Martin RR (2006) Epidemiology of strawberry pallidosis-associated virus and occurrence of pallidosis disease in North America. Plant Disease 90(10), 1343-1346.