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

Rootstock suckers Despite meticulous preparation of grafting material on a permanent basis, inter alia to prevent the possible emergence of rootstock suckers in nurseries, but especially following vineyard establishment, the sporadic incidence thereof remains a well-known phenomenon. Given the wastage of reserves, which may occur in young plantings in particular (Photo 518), it is strongly recommended that elimination thereof should be prompt, timeous and judicious – including the collar buds on rootstock material from which it normally derives. Should unsound/incorrect actions be implemented in this regard, experience has taught that the extent of such situations is not only exacerbated in due course, but also that permanent curtailing measures are increasingly compromised (Photo 519). Herbicide phytotoxicity Based on severe phytotoxic interventions associated with the unsound/incorrect application of herbicides, the meticulous incorporation and application of guidelines based on expert chemical herbicide control strategies cannot be overemphasised. In this regard the priority status of timeous application of chemical products may be singled out in order to prevent, at all costs, the possible uptake(s) through fresh pruning wounds or even swelling/emanating buds in exposed grapevines (Photo 520). Topgrafting Successful topgrafting of existing grapevines to alternative cultivars is based mainly on: (i) achieving high take percentages with normal and effectively functioning graft unions and (ii) exercising judicious actions to achieve complete grapevine development during the same growing season. Despite guidelines in this regard having been specifically stipulated, it may be expected that – especially in respect of the latter, should either injudiciousness or negligence prevail – the particular season be sacrificed and inputs that had been remissed be transferred to the following year (Photo 521).

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