With the ever increasing daylight hours as we enter the spring season, the vines are showing signs of bud-break and the promise of new growth and another cropping cycle. Many vineyards in the Margaret River Region that have early varieties such as Chardonnay are already showing new green shoots, while later developing varieties such as Cabernet Sauvignon are just showing some bud movement, at this early stage referred to as “wooly bud”.
There is no set rule as to what constitutes the right temperature or length of daylight to start the process of budbreak. Instead, there are hypothetical requirements of winter chilling that will place the buds in dormancy and this is necessary before the buds will break. After chilling, buds will resume growth once the environmental conditions become favourable. Certainly, there is good reason to understand that healthy and well nourished vines will respond differently compared to vines that may have been stressed in the previous year and that other cultural practices such as the timing of pruning may also affect the timing and success of bud-break. For instance, later pruning may result in later bud-break and this is a strategy that a viticulturist can use to some advantage.
In Margaret River, the start to spring can be quite cold, wet and windy. This isn’t so good for budbreak and the newly emerging shoots can be damaged For this reason; early varieties such as Chardonnay may be pruned as late as possible (pruning can be left as late as wooly bud in some vineyards) to delay the onset of bud-break. The intention by the viticulturist is to target less damaging weather by offsetting budbreak by a week or two later into September.
As you could imagine, it’s not always achievable to hit good weather and this year’s cold and wet start to spring is proving a difficult challenge. In many vineyards, we accept seasonal variation and work with the variation to create the best result through to vintage. We trial many different strategies and continue to seek out solutions to reduce risk and increase the success of budbreak and shoot growth in difficult years. Some of the more successful strategies I have observed include physical wind barriers and site selection. I have seen great success with planting trees as wind breaks and even tall cover crops such as cereal rye to reduce wind velocity, some vineyards use shade cloth material attached to the upwind side of the vine trellis as a more permanent barrier to wind. Site selection is important when planning a vineyard and a elevated rocky site for a vineyard may improve the absorption of heat and provide a longer period of warming temperature in the early vine growth period. The importation of rocks to absorb and hold temperature is a traditional method that has been used with success in some of the older vineyards. There are other effects from site selection that can improve success. Row orientation in line with prevailing wind (lets the wind pass through the vineyard), providing a north facing slope to capture the sun to improve heat load and providing well drained soil to improve soil temperature and root development early in the growing period are all quite practical steps in improving early season bud development and vine growth. Somewhere in this matrix of variables there is another solution to improve yield and quality and the viticulturist continually seeks out any opportunities!
Recently there has been a revelation with the promotion and use of kelp extracts to help condition the new vine growth from the harmful effects of cold and windy weather. We already know that kelp extract would help condition the vines to hot weather but hadn’t fully understood the benefits kelp can bring to offset the effect of cold temperature and the stress on the vines early in the growing period. There are many different kelp products available and we need to better understand them, especially in regard to viticulture and quality wine production. Kelp is possibly the fastest growing of all plants and considering the cold saline water environment in which it grows, has developed the ability to survive and proliferate. The harvesting of kelp from castings on the beach or harvested from the ocean as a renewable resource, lends great hope to the sustainability of supply and environmental consideration in using kelp. It would be most interesting to assess the benefits that some kelp products can bring in promoting root development, shoot growth and bud fruitfulness under difficult growing conditions. If I have learnt anything in the past few years, it has been not to discount or rubbish any natural (organic) concept and to better understand the benefits of organic and biological principals. We may think we have invented something new…but in fact we may simply have reinvented something that was well understood by our forefathers but lost in time.
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.