Vineyard canopy management practices for improving grapevine

The main conclusions from a four-year study of trellising, row spacing and pruning level of Cabernet Sauvignon at the Oakville Experimental Vineyard are as follows: 1. Reducing row spacing from 12 feet to 8 feet increased crop yield by 35%or 2.8 tons/acre with little or no significant difference in fruit composition. 2. At each of the three row spacings, quadrilateral cordon (QC) trellised vines produced approximately two tons/acre higher yield than bilateral cordon (BC) trellised vines averaged over a period of four years. 3. At the same level of “Brix at harvest, QC fruit had lower pH and higher levels of anthocyanins than BC fruit. 4. The higher level of anthocyanins in QC fruits than BC fruits was correlated to greater amount of photosynthetic active radiation in the fruiting region of the former treatment. 5. Increasing the pruning level from 24 to 60 buds per vine increased crop yield from 6.6 tons/acre to 11.0 tons/acre. 6. With increase in the number of buds per vine from 36 to 60 there was an average of 7 to 10 days delay in ripening. 7. At harvest, fruits from vines pruned to 48 and 60 buds/vine had lower pH, TA, malic acid and K and higher anthocyanin than vines pruned to 24 and 36 buds per vine. 8. Dividing the canopy, reducing distance between rows, and increasing the number of buds per vine all reduced shoot length, shoot weight, pruning weight per vine, and primary and lateral leaf area per shoot and increased the cropping efficiency. 9. The canopy density of QC trellised vines was significantly less than BC trellised vines. 10. Sensory analysis showed that BC wines could be distinguished from QC wines. 11. Sensory analysis could not distinguish between low crop wines (24 buds/vine) and high crop wines (60 buds/vine).