Grapevine yellow speckle — a newly recognized graft-transmissible disease of Vitis

Abstract

Evidence is presented to show that many grapevines showing leaf symptoms which, particularly when intense, cannot be distinguished from those caused by strains of grapevine fanleaf virus (GFV) or tomato ringspot virus (TRSV) are infected with a previously undescribed disease for which the name grapevine yellow speckle (GYS) is proposed. The causal agent of the disease has not been isolated, but it is graft-transmissible from infected to healthy grapevines. It has not been transmitted by sap inoculation to herbaceous plants. The disease has been detected in some grapevine cultivars grown in Australia for many years, and also in several other cultivars and rootstocks imported from California over the past 10 years. There is no evidence of natural spread or of seed transmission. Attempts to eliminate GYS from plants by heat therapy and propagation of tip cuttings have been unsuccessful. Mataro and LN33, the best indicators for GYS at present, are not entirely satisfactory and there is a need to find an indicator which will detect GYS in a wide range of environments. The disease has not been previously detected, probably because of its similarity to GFV and TRSV and its peculiarity in expressing symptoms only in some environments.