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Wet year provides valuable comparison in netting trial

RD&A News | March 2021
12 Mar 2021
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A drought year followed by a wet year has provided a valuable comparison for the Greater NSW and ACT Regional Program’s ongoing netting demonstration trial.

2020 was a perfect year to showcase the benefits of netting in the Hunter Valley and Orange, protecting fruit from heatwaves, sunburn and bird damage.

Black and green nets provided greater protection than white netting, which provided protection levels similar to the control (un-netted). 

But would the results change dramatically in a wetter year?

This year’s significantly wetter season with above average rainfall in both the Hunter Valley and Orange provided some interesting answers, says Darren Fahey, Development Officer – Viticulture, NSW Department of Primary Industries.

The research team applied netting at both sites at full bunch closure and left them on until commercial harvest date.

They found:

  • Solar radiation was reduced by 56 per cent under the black netting compared to the uncovered row at the Hunter Valley site during both measuring periods.
  • Solar radiation was reduced under green and black netting by 34 per cent and 38 per cent, respectively, compared to the uncovered row at the Orange site. Interestingly this result was only apparent during one of the measuring periods.
  • Overall, there was a declining trend for intercepting solar radiation from white, green then black netting respectively at another sampling point in Orange.

But it is bunch weights that really impressed.

‘At the time of writing, yield assessments for the Hunter Valley Shiraz site showed significantly increased bunch weights in all net treatments compared to the control, from 11 per cent under black net up to 22 per cent increase under the green netting’, Darren said.

Netting did not have any influence on berry weight and there were no significant differences in temperature or humidity at the Hunter Valley site.

Vine leaves in all treatments showed signs of downy mildew. Bunches from the un-netted rows had a higher proportion of shrivelling, raisined and diseased berries, whereas bunches with black netting had a higher number of small green unripe berries.

(Orange Chardonnay is yet to be assessed at harvest and grape quality from both sites are still yet to be analysed).

Biodiversity trial

Building on its biodiversity demonstration trial, a further four biodiversity plots were planted last year across the Orange region, in another regional program activity.

Previous research by Mary Retallack of Retallack Viticulture showed that introducing native flowering plants to the vineyard offers many benefits, from increasing beneficial predatory insects such as lacewings and ladybird beetles to providing pollen, nectar and shelter.

A selection of native grasses, flowering shrubs and small trees from locally grown provenance collected seed was planted at Philip Shaw Wines and Nashdale Lane Wines in April 2020.

‘The plots were laid out with ground covers and grasses at the boundary edges, small spikey shrubs towards the middle and trees down the centre line of each plot.

‘This type of planting is designed to attract birds and insects as they pass the low growing edges (ground covers and grasses) into the protective area (spiky shrubs) and the inner sanctum (trees) providing a habitat haven’, said Darren.

Baseline monitoring of insect populations was undertaken just after planting and ongoing year monitoring will allow the team to assess and compare changes as the plants develop.

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This content is restricted to wine exporters and levy-payers. Some reports are available for purchase to non-levy payers/exporters.