Engelbrecht, D.J., & Kasdorf, G.G.F. 1990a Field spread of corky bark, fleck, leafroll and Shiraz decline diseases and associated viruses in South African grapevines.. Phytophylactica 22(3): 347-354.

Notes: Field spread of graft-transmissible diseases and associated viruses in a Vitis vinifera cv. Tinta Barocca vineyard to healthy interplanted LN-33 (a Vitis hybrid) vines was studied. In the 7th season of planting, 71% of the vines showed symptoms of grapevine leafroll (GLR) disease, and all 71% tested positive for GLR-associated closterovirus (GLR-assoc. CV) Type III. C. 30% of diseased LN-33 also contained grapevine A virus (GAV) which appears to depend on GLR-assoc. CV Type III for transmission. One of these vines also carried GLR-assoc. CV Type II, while another contained isometric virus-like particles which were serologically similar to Castellano's virus-like particle, and which produced typical grapevine fleck symptoms on V. rupestris cv. St George. On indexing to V. vinifera cultivars Shiraz and Gamay, a further 2 LN-33 vines with GLR symptoms were found to be latently infected with grapevine Shiraz decline disease. Field spread of grapevine corky bark disease to an LN-33 vine, found infected with GLR-assoc. CV Type III, was observed. GLR-assoc. CV Type I was not detected in the LN-33 vines despite its presence in the Tinta Barocca vines. Random field spread of several graft-transmissible diseases and viruses into the interplanted LN-33 vines suggests active participation of the vine mealybug, Planococcus ficus. This known vector of GLR disease, GVA and GLR-assoc. CV Type III was found in the Tinta Barocca vineyard.