Chris Cooper and Rob Saunders, vine specialists in the Hutchinsons Horticultural team, discuss the season to date in vineyards.
The ideal flower initiation conditions from 2017 combined with the warm spell of weather we have all been enjoying has resulted in the best crop set that has ever been seen in the expanding GB wine grape industry, and crops are growing well. Vines are generally well adapted to dry conditions with good root systems that scavenge out water and nutrients.
There are a couple of stress points to look out for, following the dry conditions. The first is in new vines, planted in May and have had no rain at all since.
- If weed control has been carried out well, the vine is not directly competing with weeds and should have grown away. If weed control has been poor, the vines themselves suffer from competition.
- In year three when the vines will typically carry its first crop of fruit. With excellent crop set the question arises is there any need for thinning? Theory says that each bunch of grapes requires 10-14 leaves to capture sufficient sunlight to ripen the fruit. Rob reports he has seen one plant with 44 bunches! There were certainly not over 600 leaves on that plant to provide the optimum photosynthetic power! Selective green harvesting is the option in this case.
- To obtain a good yield, good canopy management and bunch management are required and help restrict any spoilage due to diseases such as Botrytis. Air movement within the canopy is therefore important.
Vigilance is still required, with powdery mildew putting in appearances in some vineyards, on-going issues with the pests infrequently encountered in the UK at this time of year such as caterpillar and vine leaf blister mite and the potential of heavy rain to trigger botrytis and downy mildew infections, harvest is still a way to go. Wasps are already seeking out ripening grapes as are birds, badgers and deer.
Viticulturalists believe the crop is going to be a bumper one, but one never knows until picking is finished, with harvest dates similar to unfrosted vineyards in 2017. The added good news is that flower initiation for the 2019 season will have been good, one season at a time.