Troublesome or difficult seasons are an unpredictable but inevitable part of viticulture and winemaking, even in the seemingly ‘blessed’ regions of Western Australia. The aforementioned seasons are primarily characterised a combinations of high or low temperatures, and/or dry or wet growing and/or ripening seasons. These kinds of seasons can not only present potential issues pertaining to fruit and wine quality, but yield and long term vineyard health and management costs.
The above mentioned issues need not necessarily become a reality. Through adhering to tried and tested viticultural basics and management strategies, troublesome seasons need only be that, and great seasons all the more gratifying and memorable.
We have compiled a checklist in order to provide a basic set of parameters to follow, and concepts to keep in mind with the oncoming season.
It is important to have a regular nutrition program in order to top up levels of basic nutrients and trace elements. A small amount applied often is the best approach, especially when tied in with petiole analysis each year at 50 % flowering and soil analysis every 3 years. Nutritionally depleted vines have lower carrying capacity, are slower to ripen and have increased risk of disease and insect attack. A balanced nutrition program is essential to profitable viticulture.
Trellis and irrigation
Clips and wires need to be in place and working. Missing post or clips place greater stress on surrounding infrastructure and increase failure of the system. An open and suitably solarized canopy architecture is fundamental to wine quality, long term fertility and well as a strong management tool for pests and disease. Sections of vines which roll due to missing infrastructure create unacceptable quality issues.
Working irrigation, with uniform delivery volumes is a critical management tool in most WA vineyards.
A permanent ryegrass and clover cover crop is one good option to nourish the soil, improve drainage, increase soil carbon, nutrient recycling and improve vineyard access. These systems, with sheep grazing or slashing with undervine placement of the mid rows have created many sustainable farming systems.
It is important to control grass weeds such as Kikuyu and couch grass which will deplete vine capacity, nutritional health and often contribute to late season stress and humidity aka mould issues. Early management of these aggressive species gives most economical results.
Pruning and canopy management
Pruning is a critical control point in the system. Kliewer from California, Smart and Robinson from Australia, and Intrieri from Italy have described various idealized parameters for vine performance. Fortunately, these independent researchers have very similar conclusions. The observed vineyard is compared to the ideal using numerous indicators (Table 1).
ummer, with around 90% less rain for than the long-term average. Those who risked all by waiting for the Indian Summer, were rewarded with tannin ripeness and the retention of the most beautiful fruit perfumes at relatively low sugar levels. The vibrant purple reds are now maturing in French oak, along with many Chardonnays, while some of the aromatic SBS styles are about to be bottled. We believe that 2017 will become known for fragrance and softness.
The 2017 vintage also highlighted the importance of best practice vineyard management, focusing on the basics of open and well solarised canopies, with balanced crop loads, so that the fruit could ripen at a reasonable pace. As we approach the pruning season, it is time to focus on getting the architecture of the canopy correct, and setting the foundations for the 2018 vintage.
After budburst, go into the vineyard and count the emerging shoots. If the number of (potential) shoots is to specification, then the pruning has been successful and no more action is required. If the bud numbers are over the specification by an unacceptable level, (often caused by non-count shoots), then implement shoot thinning. Removal of the shoots from the 1st leaf stage to 10 cm is the cheapest and most beneficial method to reach specification.
It is important to note that the decision for shoot thinning at the early stage must be balanced with the risk of early season hails. For example, in an early bursting variety like Chardonnay, the shoot thinning may be delayed, where as in a late bursting variety like Cabernet, the shoot thinning can be earlier.
This is important for both spur and cane pruned vines. Thinning of non-count shoots on cane pruned vines is critical for both quality, productivity, and risk management. It is also important to shoot thin early so as not to waste energy which can be used to ripen fruit.
Pest and disease management
Many of the wines we produce are exported to various other countries; hence it is critical to follow the AWRI Dog Book (Agrochemicals registered for use in Australian viticulture) for the relevant season.
We recommend a 60 WHP for sulphur sprays as elemental sulphur is a primary cause of reduction in wines, a problem which often cannot be corrected, or the corrective measures strip the wine of aromatics and flavour. In some cases, the wines become completely faulted and not fit for commercial use.
No sulphur post-Christmas for whites and last sulphur for reds by 15 January is a sensible ball park, similarly the last sulphur of the season should be at sensible and relatively low levels to reduce residues, reduction issues and sulphur x sunburn of the fruit.