A Guide to Grapevine Abnormalities in South Africa - P.G. GOUSSARD

Fleck.

confused with herbicide damage (Photo 256). Shoots from affected grapevines have the tendency to grow downwards, but are not rubbery as with corky bark disease (Photos 257 & 258). Although enation is classified as a graft transmissible virus disease (Graniti et al ., 1965), there is little in the literature about the visually detectable effect thereof on berry and bunch morphology. Seeing that abnormalities characteristic of enation often occur in grapevines infected with fanleaf and even stem grooving, one can expect yields in such instances to be considerably compromised (Photos 259 & 260). On the whole one should bear in mind that characteristic abnormalities associated with fleck and enation may be greatly influenced by the separate or combined incidence thereof, with other harmful virus diseases. Once again this emphasises the necessity of ongoing use of certified plant material exclusively – as authenticated by the high phytosanitary quality thereof – in any form of grafting and propagation.

PHOTO 249. Characteristic of fleck is the incidence of chlorotic, transparent vein interruptions, especially of the finer veins of the third order in the indicator cultivar ( Vitis rupestris cv. St. George).

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