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

Shiraz decline.

PHOTO 242. Typical of grapevines associated with Shiraz decl ine is the incidence of abnormally thickened (swollen) graft unions with cracks – a trend that is continued on trunk sections at the top end of graft unions, while visually rootstock components appear to be normal.

PHOTO 243. Here one sees cracks on swollen graft unions (Photo 242) with the accompanying hardening of affected wood sections. Note that the development thereof is clearly visible, unlike the rootstock component that appears to be unaffected.

PHOTO 244. Grotesque cracks/grooves/ridges – which continue on the trunk above the top of the graft union (which has a twisted/distorted appearance in this instance). Not to be confused with stem grooving.

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