What held up this year's harvest?

It's been a season of extreme, sometimes isolated, weather events - with some vineyards hit hard by storm and hail damage; others contending with floods; and some recording high temperatures. Despite all this, many growers are expecting it to be a season that delivers on both quality and quantity.

We've asked a group of experts from around the country to comment on what's impacted vintage this year and to give us an outlook on what to expect in the coming season.

Marcel Essling, Senior Viticulturist at the Australian Wine Research Institute, gives a national overview while we take a look around the country with Colin Bell in Western Australia, Mike Hayes in Queensland, Marty Smith in Tasmania, Ian Macrae in the Riverland and Andrew Mclean looking at regions in SA, NSW and Victoria.

Q. What impact did the winter season have?
ME: Ample winter rainfall occurred in many regions. This is positive because it leaches salts from the soil profile. Vines need cold temperatures to go into dormancy and this winter the requirements for dormancy were met.
AM: Most viticultural areas experienced either their wettest or second wettest winter on record. On top of this, wet conditions were experienced at both the end of May and September in these regions, making the completion of pruning quite difficult for many growers.
Most growers finished pruning in a timely fashion, although there were a significant number of blocks in the Riverina that were pruned later than normal, some even post bud burst due to wet ground. Budburst in these blocks occurred a week or two later than the region average due to the late pruning (with a few outliers even further behind due to being pruned post budburst).
MH: Not as much as what I thought. I thought it would have been worse as there was a bit of later season frost. We have a frost machine that we normally turn on one or two times a year, we had to turn it on nine times this year.
IM: The winter was colder and wetter than average. The wet winter meant that less water needed to be applied than necessary during this period to keep soils moist and for salt leaching. At that time, irrigators were facing the prospects of severe restrictions on water allocations.
The wetter winter was helpful to reduce water use and save water for the irrigation season.
MS: Winter was warmer than average but extremely wet. The main issue was vineyard machinery access for barrel pruning, Klima pruning and herbicide. We also lost a lot of pruning days to rain.
The wet ground also caused a lot of problems when trying to get early fungicides on.
CB: The 2016 winter and spring were more in line with long-term averages and less typical of the last eight years. The spring was cool and overcast with few sunny days which is likely to reduce fruitfulness in 2018. The region received close to 1200mm of rainfall, with lower average maximum and minimum temperatures in comparison to the last 8 years.

Q. Summer seemed to be reasonably mild and very wet, apart from the extra fungicide and herbicide applications required, how has this impacted on vine growth/canopy structure and fruit development?
ME: In a typical year, it is the drying out of soils that stops shoot growth and signals the vine to ripen fruit. The high levels of soil moisture seen this season meant few constraints on shoot growth and this required increased canopy management such as trimming.
It is likely that where shoot growth continued late into the season, ripening will be delayed.
AM: Conditions have been variable across lots of viticultural regions, where relative humidity has been at levels in most regions far greater than normally experienced. With good soil moisture profiles to start the season and consequent good canopy growth, the humid (and in some regions wet) conditions and better canopies have created high disease pressure in many regions, particularly for powdery mildew in more susceptible varieties.
In reference to the warm inland regions, the switch between cool conditions (and rainfall in some areas) and the current hot weather means that growers are very carefully monitoring water applications to maintain current fruit quality throughout the current weather event successfully.
Whilst some of the late varieties in cooler regions may run the risk of senescing prior to desired sugar accumulation, overall yields look like they will be in line with long term average and prospective fruit quality looks to be very promising, with the potential of an exceptional year in some regions.
MH: We just got out highest temperature on record, getting above 40 degrees. Average has been, quite warm, slightly below cropping temperature. Around 34-35 degrees, which is warm for up here. Carried out our normal spray regime, I prefer preventative programs, organic as possible.
As much as you can stay organic you're doing a good thing, prevention rather than cure.
IM: The summer has been mild and rainfall has been about average. Humidity has been uncharacteristically high for the Riverland for summer. The mild and humid conditions have not only favoured diseases such as powdery mildew but also pests. Vine scale, mealy bug and erinose have not been seen in such high numbers for years.
The mild and humid conditions have promoted continued canopy growth, requiring constant trimming to maintain open canopies and direct vine energies into fruit development rather than vegetative growth.
Fruit development stages and ripening is now at least three weeks behind last season.
MS: The good soil moisture from the rain has taken the pressure off irrigation but has produced some very big dense canopies. We will have a huge focus on trimming, lateral removal and leaf plucking from now on.
CB: The Margaret River region has had a milder year in comparison to short term averages. South Western Australia have not received unseasonal rain with observations been close to long term averages. Late summer in the South West is susceptible to northern low pressure systems moving heavy rainfall down the west coast.
Margaret River, Growing Degree Days (GDD) up to 31 January, equated to 910, below the short-term historical mean of 1034 (Witchcliffe station 2005-2016). The coldest season in this data set is the 2006 Vintage, which had accumulated a GDD of 759 up until the 31st January.
Veraison has been delayed in early varieties, but less so in later varieties.
Margaret River is predicting a later start to vintage and a smaller gap between the harvest of early and late varieties. A more compressed vintage.

Q. What impact does a 'later' 2017 season have on next year?
ME: A two or three week delay to harvest (compared to recent years) is not likely to have much impact on next year. In most regions, there will still be enough time post-harvest for functioning leaves to store carbohydrate reserves before leaf fall.
One factor from this season that could impact the next is the weather experienced around flowering. If conditions were cool and overcast, inflorescence initiation in next year's buds will be fewer than if the conditions had been warm and bright. This will have implications for bunch number per shoot next year.
AM: A later 2017 vintage shouldn't see too much of an impact on the majority of regions. The main risks tend to lay with the cooler regions and their late varieties where the opportunity for carbohydrate storage may be reduced.
MH: I'm an optimist, I always on the bright side. I'm drawing a long bow here but with climate change we will be slightly dryer, and producing really high quality wines.
IM: The later the season, the later grapes are harvested, the less time there is for carbohydrate restoration. This can potentially adversely affect early season vine growth and early inflorescence development.
MS: The average conditions at flowering will knock around our bunch numbers for next year, particularly in our key varieties of Pinot Noir and Chardonnay. That seems a long way away though, need to get this vintage out of the way first!
CB: It's likely to have poor fruitfulness due to cool overcast spring conditions

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