PCR analysis confirms an expanded symptomatology for Australian grapevine yellows

Abstract

In the 1994/95 season, unusual, widespread and generalised foliar symptoms, similar to those of Australian grapevine yellows (AGY), occurred in late summer-autumn in many regions of Australia. They were confirmed by the polymerase chain reaction (PCR) assay as being associated with the presence of the phytoplasma of AGY. In contrast, the early-season (i.e. late spring-early summer) symptoms of AGY were less common and generally confined to isolated shoots. Positive PCR assays for phytoplasma (65 out of a total of 90) were obtained only from vines showing AGY-like symptoms while none of the 88 PCR assays for symptomless vines were positive. The disorder of restricted spring growth syndrome, widespread and damaging in spring 1994, occurred in some vines which also later showed AGY-like symptoms in the autumn.