Equipment, irrigation regimes, buckwheat & vigour comparisons

By Max Marriott
Assistant Vineyard Manager

The field day at School House vineyard on Tuesday the 12th of February provided an opportunity for growers from around the region to see various forms of machinery in action that are typically used on organic vineyards. Under-vine cultivators, inter-vine mowers, silerators, compost spreaders and other bits and pieces were on display, each with their own pros and cons. After introductions on the equipment from the respective vineyard managers, and witnessing the efficacy of each implement, the consensus from all present (some 50 local growers) was that each piece of equipment has a predisposition for certain sites, soils and management regimes.

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Grant and I had an opportunity to address and update the group on the season’s progress at School House vineyard. The pruning regime had essentially been the same for both sets of organic and conventional blocks, with some more aggressive pruning (to vigour) in areas that suffered stress the previous year; namely bony parts at the bottom end of the vineyard and sections of the organic 777 clone. There was no damage from the frost in early November and bud break was even across both the organic and conventional blocks.

As for irrigation regimes, readings from both blocks indicated similar water requirements, though as the season progressed higher amounts of vigour – and growth – in the conventional blocks necessitated slightly higher water needs. A brief trial in November (October was cool and wet) experimented with irrigation soaking – reduced frequency, higher doses – to encourage deeper water penetration and promote subsoil root exploration (particularly for the organic blocks that had weed competition to deal with). However, the sheer nakedness, lack of OM and sieve-like qualities of these soils prevented any short term (let alone long term) water holding ability, and as a result the irrigation regime was switched back to a regular frequency with smaller doses. With a dry, very hot December and 15 irrigation stations to contend with, the system was at times running 24/7.

Buckwheat doing its job

Buckwheat doing its job

Buckwheat and Phacelia were intentionally drilled late as an experiment to avoid the vagaries of spring frosts. In hindsight, this was fortunate given the (ground) frosts on the vineyard in early November. The buckwheat strike was excellent once supplemented with well-timed rains in early January, whereas the Phacelia was less successful. As the key attractor for parasitic wasps, it was desirable to have the buckwheat in good shape this season after frosts culled the previous season’s population. Visually, it’s been interesting to note a reduced incidence of leafroller caterpillar, though more thorough analyses will be forthcoming from Fruition’s assessment team in due course.

The most obvious difference between the two regimes has been vigour. Certain pockets of conventional vines across the vineyard have been too vigorous, and certain organic vines have not been vigorous enough. The 12 rows of organic 777 have been particularly low in vigour (evident in 2012 by its reduced cropping rate to approx. 4t/ha), and on consultation with Bart Arnst, these twelve rows will form part of an in-house trial where we will experiment with some interrow cultivation on several rows (which could include ripping to break up compact layers underneath tractor tracks), blood and bone on several rows and then a control. It’s thought that the timing of under-vine blading/mounding could also be at play, along with weed mats surrounding vine trunks that will require hand weeding.

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