ISHS Acta Horticulturae 754: International Workshop on Advances in Grapevine and Wine Research
INTER-RELATIONSHIPS BETWEEN VINE VIGOUR AND THE INCIDENCE OF BUNCH STEM NECROSIS IN 'CABERNET SAUVIGNON' GRAPEVINES |
| Authors: | A.H. Pickering, I.J. Warrington, D.J. Woolley |
| Keywords: | root pruning, heading, reflective mulch, shading, source-sink relationship |
| Abstract:
Bunchstem Necrosis (BSN), is a physiological disorder in grapes, which results in unripe shrivelled berries with poor quality attributes. Past research into this area is conflicting with many different hypotheses being proposed to explain the disorder. Vines on SO4 rootstock, a high vigour rootstock, have demonstrated high incidence of BSN and the published literature has also indicated that shading of vines at a particular time may influence BSN incidence. In this study, it was proposed that there was a positive relationship between vine vigour and BSN incidence due to a shift in the source-sink relationship between the developing fruit and vine growth. Treatments to manipulate shoot vigour and the source-sink relationship were applied to ‘Cabernet Sauvignon’ grapevines grafted on SO4 rootstock. Treatments included root pruning to reduce vigour, heading back of canes, the application of a reflective mulch to increase vigour, 50% shading for three weeks prior to flowering, and 50% shading for three weeks after flowering. A strong positive relationship between vigour and BSN incidence was determined in the first growing season. In the following season where all treatments were reapplied except root pruning, the relationship was not as strong but was still positive. Root pruning still reduced BSN and vigour in the second season, just as heading back of the canes and the reflective mulch increased vigour and BSN incidence. Environmental conditions between the two seasons were very different and this may have influenced the observed responses. Neither shade treatment significantly changed the vigour of the vines in either season. Shade prior to flowering reduced BSN incidence in both seasons. However, shade after flowering only influenced the BSN incidence in the second season where the BSN incidence was increased. These results provide evidence that some management practices are available to manage this disorder but their effectiveness will be influenced by the prevailing environmental conditions especially around the time of flowering. | |
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