Here we are out in the vineyard in the middle of spring and enjoying the kindest viticultural weather that I can remember in any year at this stage of vine development.
The vines are responding positively to the extended period of drying and warming soils and are free from the usual cold and windy conditions that can hamper shoot development in spring. Already we see vine shoot growth that is 7 to 14 days ahead of normal timing and an evenness of budbreak and shoot length that will provide the canopy of foliage that is all-important for ripening later in summer. Many shoots are presenting multiple inflorescence (pre flowering) bunches and this indication could be the potential for a bumper crop across all varieties for vintage 2011.
An interesting observation out in the vineyard in spring 2010 is that there is much less water shoot development than has been see in previous years. The term “water shoots” is given to the shoots that grow from latent buds (buds not specifically retained at pruning for fruit). This natural phenomenon is possibly due to the evenness of budbreak of the retained buds and vine growth performance that encourages strong shoot development free from the damage of shoot tips caused by inclement weather. The damage of shoot growing tips can result in the stimulation of latent buds and this is an evolutionary protection response, it makes grapevines very hardy plants. The net result of the current kind weather is the vine supporting the primary shoot growth and not forcing latent buds into production.
The significance of less water shoots this year is in less crowding of shoots in the fruit zone. We generally prune vines to leave 20 to 30 buds per lineal meter of row (that is on a vertical shoot positioned canopy) and then aim for the quality standard of not more than 22 shoots per lineal meter, this is manipulated by the removal of additional shoots. The purpose of regulating shoot density is to encourage airflow and sunlight into and around the fruit and this helps with disease control and also ripening the fruit. The fact shoot density this year appears to be happening naturally in many of our vineyards results in less hand work (we like that!) and importantly is the greatest potential of quality fruit for the coming vintage as a result of natural vine root and canopy balance.
Rapid growth of shoots on vines in early spring can result in much more fruitful buds for next year’s crop. The relationship between root and shoot development and the interaction with plant growth hormones within the vine root system and foliage create bud fruitfulness in the newly forming buds. Simply, when the vineyard environment provides warm and moist soils that are adequately catered for with micro-nutrient and then combined with warm ambient temperature with high light intensity, the promotion of plant growth hormone biosynthesis within the vine encourages bud fruitfulness and flower formation, all important for this vintage and also next year’s crop yield performance.
Rainfall for the period January to October 2010 is almost 200mm less than average and while there is concern with drying soils and a long dry start to spring we can see that the dams are full and the creeks and rivers are still flowing, albeit flows are much less than normal. Many viticulturists are pre-empting the use of some supplementary irrigation at the lead up into flowering to ensure that fruit set occurs in perfect soil moisture. The retention of developing berries free from “shatter” or loss will be due to the vine response to drying soil conditions. Some managers use sophisticated moisture sensing equipment, while others use less complicated methods. Personally, I prefer to use my observation of vine performance, a shovel to dig into the earth and back this up with whatever objective measurement may be useful. It is the skill of the viticulturist in understanding the individual vines response and then managing the opportunity to provide an environment that will produce fruit of the highest quality that is all important. In many of our older vineyards there is no irrigation and it is interesting to note that there is a strong relationship with these vineyards and the high quality fruit that is produced in the Margaret River wine region. Many of the older vineyards never had irrigation at development and were established using techniques that maximized conservation of soil moisture and encouraging root dispersion deep into the soil (we have seen vine roots at least 8 metres down into the clay).
These tough old vines have roots and trunks that, over many years, drought proofed themselves against variations in soil moisture and have a physical ability to produce fruit with exceptional colour, flavour and aroma. Dry-land vineyards will express seasonal weather variation in a positive manner, the end result can be exceptional fruit quality in years where the topsoil tends to be drier in the period between fruit set and veraison (berry softening and colour change) and from what we are seeing out in the vineyards this spring, we are looking at the potential for one of the truly great vintages in 2011.
contributed by Bruce Pearce
Margaret River Discovery Tours
Sean Blocksidge is the owner operator of the Margaret River Discovery Company, an avid photographer, blogger and South West WA ambassador. In 2010 he won Western Australian Guide of the Year and his tours have been rated the #1 thing to do in Australia on the Tripadvisor website for the past two years.