With flowering completed and fruit set established the grapes are now increasing rapidly in size and filling bunches. The 2008/09 growing season has created a few challenges with unusually poor flowering in some vineyards which has resulted in far fewer berries on bunches than what would normally be expected. These “shot” berries are flowers that fail to develop into normal berries and sometimes end up simply falling from the bunch. This poor fruit set resulted from problems associated with pollination or fertilization at flowering and in this season was most certainly caused by cool and wet conditions at flowering. In the past we have seen the results of poor flower set due to very cold night temperatures, and this is sometimes overlooked as we can experience warm days but with quite cold nights. These shot berries may still grow into very small, round and seedless fruit but are generally not attributed into the weight estimates conducted in the vineyard prior to harvest. The Gin Gin clone of Chardonnay is renowned for regularly producing these small berries (referred to as “Chickens”) and these small berries are seen as being instrumental in the quality attributes for winemaking in this variety.
Associated with this phenomena of shot berries this season, has been the emergence of what is known as the Apple Looper. This small caterpillar like grub has been the subject of many reports of losses to berries in vineyards this season. The looper has a like for the small undeveloped berries and has been chewing their way through bunches voraciously, causing surface damage to larger developed berries and stalks along the way. Not a lot is known of this pest in grapes and we are not sure if this is a seasonal pest as a result of unusual seasonal weather conditions or something that will need to be expected in future years? Many growers have simply monitored the looper in the vineyard and found that the losses don’t warrant control; other vineyards have had ongoing losses and have implemented a control program.
We are now entering the period in which berry softening, increasing sugar and colour change in red varieties occurs, this period of change is called “veraison”. Through the early period of veraison, the viticulturist will assess evenness of bunch ripeness and then decide whether bunch thinning to even up crop ripeness and/or to reduce crop to promote sugar accumulation will be necessary. Much of the fruit removal is done to promote even ripeness of bunches and the even distribution of crop within the canopy, these adjustments help with managing and increasing the chance of producing a quality crop of fruit.
Another important job for vineyard managers at this time is to forecast the crop weight. This isn’t an exact science and relies on some experience to predict yields. Many managers will mark data panels across the vineyard as permanent assessment sites. The data panels will have the bunches of fruit counted and then a sample of berries weighed, the sum of which is calculated and multiplied by the vines per hectare and a adjustment in weight added for future sugar accumulation and seasonal variables. A deduction is then also made for stalks if the fruit is to be machine harvested and then another reduction can be applied for potential juice or berries lost during harvest….. At the end of this process we hope to be close to the total harvest tally. Not always precise but none the less an important tool in predicting the need to balance crop yield to vine health and also to allow the winery some planning for vintage.
Courtesy of the Margaret River Wine Industry Association
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.