By Bart Arnst, Viticultural Consultant
Bart Arnst is advisor to the focus vineyards, helping the focus vineyard managers to formulate their organic management plans.
All three focus vineyards have now had their field days in the last few weeks. The first field day at each site was generally to inform attendees of the project, its history, the objectives and the potential outcomes.
We then had a question and answer session before walking the vineyards to compare the differences, if any, between the organic and conventional management techniques. We were fortunate in Central Otago to have Dr Tim Jenkins, who is monitoring soil structure and soil life for the project, on site at the field day to discuss soil life and techniques to improve the underground habitat.
At this early stage in the growing season, all regions will be following a similar path: nutrient adjustment if soil testing shows a need; weed control in the undervine strip (be it mowing or cultivation) to allow stress free shoot growth; and early season protection from diseases such as powdery mildew (all regions) and downey mildew (Hawkes Bay).
The next field days are scheduled for December. Between now and then we will see substantial vine growth and the regional differences should become more apparent. We would expect to see Central Otago starting to dry off, and an increase in the humidity levels in Hawkes Bay with Marlborough sitting somewhere in the middle.
The control of undervine weeds will continue to be important leading into the Xmas period, however the frequency of weeding operations is often related to rainfall or lack thereof.
Pest and disease monitoring will have begun in all regions, and strategies to control either will be discussed with the vineyard managers if thresholds are reached. Meanwhile, pre-flowering powdery mildew prevention will remain the main focus. Whatever the chosen control option for powdery, it is most often supplemented with a nutritional addition.
Cooler and damp weather over spring is an ideal time to apply soil drenches to the land, be it as a nutrient, mineral or biological addition. The opportunity to “kick start” tired soils at this time of year should not be missed, especially if there has been little or no focus on soil biomass previously.
Once the period of frost danger is over, the strategy of mowing can change. A close mown sward becomes unnecessary, and indeed the benefits to biodiversity by allowing every second row to flower are obvious with the increase in insect activity. There will however be some species in your cover crop mix (either sown or natural) which you may not wish to set seed, so an understanding and knowledge of these species may prove invaluable.