Summer field visit

By Bart Arnst, Viticultural Consultant

Mission Estate  Vineyard, 14th February 2011

A scorcher of a day which had field day participants looking for shade. The latest of the series of field days planned to show interested parties the progress of the Organic Focus Vineyard project.

Caine Thompson (Mission) and Jonathan Hamlet (Villa Maria) began by giving an overview of the project to date. Caine discussed the comparison blocks and the differences he was seeing plus the cost differential to date (organic slightly cheaper).

The vineyards recently have been monitored for pest and disease by an independent body. Terry Fraser from Fruition reported a lower incidence in powdery mildew in the organic sections. No downy mildew was observed.

All regions have had a high level of powdery mildew pressure this vintage, so it was pleasing to see these results.

All varieties were well into verasion, all canopies looked good and the bird pressure had begun. Jonathan was quick enough to capture an errant blackbird; the method of dispatch was not witnessed.

Points risen pre the vineyard walk and discussion were:

1. The use of sulphur and copper in an organic system.

Firstly, it is important to note that both these elements are allowed in organic systems; they are acceptable up to certain levels by the organic certifying bodies throughout the world.

There is no doubt that excessive use will create long term problems with soil health. Copper is measurable in soil tests and will be monitored. Sulphur is often added to fertiliser in the form of prills.

We aim to reduce all inputs over time, however we must remember that this is the first year of conversion and there will be a degree of nervousness by vineyard management and the wine company’s management so we have no problems “playing it safe” with our spray program and using these inputs.

As growers move forward through organic conversion we tend to gain more confidence in the process, the products available and the site’s ability to cope with the change in farming techniques. I would expect to see a reduction in sulphur and copper use over time, and/or alternative product inputs.

2. Vigour differences.

The Pinot Gris showed a stark difference between the conventional and organic in vigour.

The conventional appeared to have gone into a vegetative phase and will require another trim. This fresh growth can also lead to more powdery mildew pressure; not necessarily to affect fruit but certainly to add to increased disease inoculum for the following season.

3. Crop levels.

Visually all comparison blocks appeared to be cropping at similar levels. This has also been Caine’s assessment.

The vineyard walk was followed by undervine mowing and cultivating demonstrations. Five separate units were available to view and we thank those who took time out to provide this operating display: DearTech (undervine mower), Braun (undervine cultivator), Stortford Machinery (Tournesol and Ecology), and Moteo Ridge (Ridgeback).

And finally thanks to HortiCentre who provided the hot and hungry with the appropriate nourishments with a BBQ and drinks at the end of the day.

Field day demo: DearTech undervine mower

Field day demo: Results from the Tournesol weeder

About organicwinegrowersnz

Organic Winegrowers New Zealand (OWNZ) is an incorporated society for organic and aspiring organic grape and wine producers. We work to encourage and support the production of high quality organic wines from New Zealand, through education, research, networking, and advocacy.
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