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

Aster Yellows.

PHOTO 271. Characteristic of Aster Yellows disease is the occurrence of a lead-grey colour on unlignified (green) shoots, which in the case of Chardonnay especially is sometimes accompanied by shallow longitudinal cracks (12:00-position) along the surface.

PHOTO 272. The lead-grey colour (Photo 271) can be rubbed off with the finger to expose the green colour of underlying shoot sections. Also note the abnormal appearance of bark sections on this partially lignified Chardonnay shoot – where, apart from cracks, small protrusions/bulges are noticeable.

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