Much of the southern part of Australia is currently experiencing a very dry winter, with many regions having received less than 40% of their normal winter rainfall to date.
Insufficient winter rainfall creates a range of challenges for grapegrowers. These include dry soil profiles in spring and dams that may not have filled due to low water run-off during winter. There are several steps that growers can take to manage dry conditions, depending on their circumstances.
If irrigation water is available during winter
When irrigation is available during winter (for example from a bore or piped from the Murray River), then the best advice is to maintain some moisture in the soil profile by applying irrigation throughout winter. Trials have shown that waiting until spring to fill the soil profile can result in excessive vegetative growth and reduced yields. As temperatures rise in spring and the canopy starts to develop, close attention should be paid to soil moisture, as regular irrigation is likely to be required much earlier than in a wetter season.
If only limited irrigation water is available
If the soil profile is dry and only limited water is available (e.g. from an on-farm dam), then the use of this water needs to be carefully budgeted. A small canopy will use less water, so irrigation should be avoided until canopy growth has stopped. Depending on the amount of water available, irrigation can be applied strategically to prevent defoliation; this would often start sometime between fruit set and veraison. The aim of any irrigation applications is as much to sustain the vines as it is to reach a target yield. Blocks with a better return may also be prioritised over blocks where the value of the fruit is likely to be lower.
Vineyard floor management
Cover crops and weeds compete with vines for valuable water. In a dry winter cover crops should be slashed, rolled or a desiccant herbicide applied earlier than usual, to help conserve water. Dry springs are also associated with an increase in frost risk. Midrow cover crops should be kept short in frost prone areas.
Other useful resources
- Maps of rainfall patterns from the Bureau of Meteorology.
- A series of spreadsheets from CCW Co-operative Ltd to help with irrigation budgeting
- A recent article written by authors from SARDI and the CSIRO: Bonada, M., Petrie, P.R., Edwards, E.J., McCarthy, M.G. The impact of winter drought on vine growth and wine quality. Aust. N.Z. Grapegrower Winemaker (644): 41-43; 2017. This article can be ordered from the AWRI library.
- Marcos Bonada’s presentation from the 16th AWITC: ‘Assessing the impact of winter drought on vine balance and root activity’.
The AWRI helpdesk provides technical support and advice to Australian grapegrowers and winemakers. Contact the AWRI helpdesk on (08) 8313 6600 or email firstname.lastname@example.org.