Growers urged to try mechanical way
Marlborough grape growers and wine companies are being encouraged to trial a mechanical thinning programme on a small section of their vineyards to thin vines and manage botrytis.
About 35 people attended one of two one-hour presentations at the Marlborough Research Centre on Tuesday to learn more about the technique. New Zealand Winegrowers and the Ministry of Primary Industries Sustainable Farming Fund provided funding for the research.
Among the research team are Marlborough Plant & Food Research scientist Mike Trought, assistant scientist Sue Neal and consultant Mark Allen.
Mr Trought said research over the past six years, including two years of commercial mechanical thinning, showed that thinning between fruit set and pre-bunch closure was a very viable and effective way of reducing crop levels. Yields looked as though they would be slightly higher than usual this year, which was part of the reason the workshop was being held, Mr Trought said.
"Yields are looking above average this year, so we're looking at alternatives for moderating crops and improving quality."
Due to the changeable weather, which posed a higher risk of botrytis, and predicted higher yields, this year was a good opportunity to consider trialling a few rows or a couple of hectares, Mr Trought said.
Mechanical thinning was a non-chemical and cost effective method of opening up the bunch, resulting in a thicker skin on the fruit and reduced risk of botrytis at harvest.
Mr Allen also discussed the technicalities of mechanical thinning such as how to set up the harvester, appropriate beater speed and the formula for calculating how much fruit to remove. Damage to the fruit was unavoidable, Mr Trought said. "There will be a certain amount of bruising to the fruit and a certain amount of ‘squishiness' in there."
Other types of thinning - cane cutting or bunch thinning by hand - left tight and susceptible bunches.
- The Marlborough Express