Vintage 2013 - Pre-Harvest
We are now about 45-60 days from grape harvest. It is a good time to assess how the vineyards are looking and what challenges are ahead. Harvest in McLaren Vale is expected to begin the middle of February with Chardonnay and Sauvignon Blanc. Shiraz harvest is likely in the last week of February running to the middle of the month.
Crops are very low and this will increase the speed of ripening and bring on a rapid harvest.
|PIC: A chardonnay bunch with some powdery mildew infection on berries - 8/1/2013. Note that hot weather in the last few weeks has not ‘killed’ this powdery. (c) James Hook|
Assessing vineyard ripening this week has been difficult as it has varied from site to site. Some vineyards have advanced quickly in the last week, with 30-50% Veraison (EL-35) occurring over the week, while in others the vines seem to have stayed the same. For example in Willunga some vines have not significantly coloured in the last 7 days and are only at 1-2% Veraison.
Extremely hot conditions on Friday the 4th of January caused heat stress where high temperatures on plant surfaces ‘burn’ vine leaves and fruit. CropWatch's weather station at McLaren Vale recorded temperatures of 40.2oC, while temperatures inside the vineyard were in excess of 45oC.
We think variation in ripening has been caused by the extreme heat. In some parts of the McLaren Vale GI fruit development has sped up in response, while in others the vines processes have stopped and berries have not progressed into colour change.
The good news is while hot day and night temperatures have affected the health and appearance of most of vineyards in the McLaren Vale Wine Region the damage is low. This is remarkable considering the extreme temperatures.
Less than 5% leaf and fruit damage has been seen. Sun damaged fruit will shrivel and dry out before harvest and will not affect fruit quality.
Where leaf burn has occurred vines still have enough functional leaf to ripen their crop. Grape quality is largely unaffected as minimal leaves have been lost the vines ability to ripen fruit is only slightly reduced. One observation is burn is worse on eastern side of the canopy and areas of low airflow.
Keeping control of powdery this season has been relatively easy due in part to a drier than average spring.
The attached photo is of powdery mildew near CropWatch McLaren Vale's Range weather station. An infection of powdery has affected all of the ‘shot’ berries. It shows you that disease was very active 4-6 weeks ago and powdery is very good at finding a way to infect fruit. This is in an otherwise well tended and healthy VSP vineyard with an open canopy.
If you are seeing signs of disease it is an indication that your spray protection practices, especially coverage, are not up to scratch. Diseased fruit this season is a sign of poor management.