By Caine Thompson, Mission Estate Viticulturist
Veraison to harvest was a challenging time in Hawkes Bay as a grape grower. During this period all blocks in the trial were well set up, with nice open canopies and good balance in terms of crop load, and progressed evenly through verasion.
So how did the growing regimes stack up?
Firstly, what we observed through the ripening period was how well balanced the organic vines were in terms of vegetative growth. This was pronounced in the Pinot Gris, with the conventional block requiring an extra trim to control the excessive vigour, compared to the organic block which didn’t require any further trimming. This same pattern was also observed in the Sauvignon Blanc, but to a lesser extent in the Chardonnay. During our sampling, which was carried out independently by EIT, we noticed that this vegetative response also correlated with a difference in brix between the organic blocks and conventional blocks. In both the Pinot Gris and the Sauvignon Blanc, we noticed at each of the five maturity tests that the organically grown blocks were significantly riper right through until harvest. Both the organic Pinot Gris and Sauvignon Blanc were approximately 0.5 brix higher than the conventionally grown blocks. However in the Chardonnay the conventional and organic were very similar. We think that this shows a direct correlation with the influence of controlled vigour on advancing fruit ripening.
Secondly, we found that berry size and average bunch weights were very similar between both organic and conventional regimes. In this first year of the project, there was no loss in yield growing organically as compared to conventionally across each of the varieties, which we were pleased about.
Thirdly, a big question mark we had going into this project was that of pests and diseases and their control under an organic management regime. Fruition Horticulture assessed powdery mildew in February and found that across all blocks, crop loss due to powdery mildew was under 1% across all varieties and growing regimes, which was very encouraging.
With significant wet weather events continuing through early March, I was concerned how all of the blocks would hold up when exposed to such severe botrytis pressure. Again Fruition assessed botrytis and sour rot, and again both regimes reported good botrytis and sour rot control. There were no significant differences between either growing regime, which really highlighted the importance of canopy management and the role it plays in botrytis control, but equally importantly this showed how well the organic blocks held up under significant disease pressure.
The decision was made to harvest all the blocks when the forecast showed another significant wet weather event forecast for a few days in the later part of March. We decided to harvest all varieties and blocks, which all ended up coming into the winery around the 21 brix mark. Actual harvest analysis was performed separately for organic and conventional varieties, along with harvest yields and juice analysis, all of which will be presented at an upcoming field day in June and again at Bragato in August.
The other big question we had was around the costs of growing organically. All of this information has been collected throughout the season and I’m looking forward to presenting this soon once final analysis has been made.
Overall I’m really pleased with the season and the quality of the fruit grown under an organic growing regime and am looking forward to what the next season brings!
Many thanks to Bart Arnst for his mentorship and guidance through year one, which has helped make this an enjoyable experience, and also to Jonathan Hamlet and Rebecca Reider for their continual support.