Chris Cooper and Rob Saunders, vine specialists in the Hutchinsons Horticultural Team, discuss the season to date in vineyards.
The 2019 crop doesn't look as abundant as 2018. Generally, individual flowers in bunches have thinned out, allowing plenty of room for grapes to expand into, and although in certain areas in certain varieties fruit set is variable there are still healthy numbers of bunches to be picked this year.
Bunch closure is upon us and will be followed quickly by veraison. These are key times to prevent the mildews from getting out of control and treat to inhibit the development of botrytis. Achieving good cover is the challenge - don't skimp on water volumes or spray until run-off, good canopy management helps.
Flowering and fruit set are behind us, ripening some way off, but considerations of harvest intervals are already constraining product choice, with the 56 day limit applying to many mancozeb containing products.
Options to control powdery mildew have increased this year. WineGB applied for an Extension of Authorisation for Minor Use (EAMU) (2990/19) for Vivando (metrafenone) which has recently been issued; it is highly effective with a unique mode of action providing another option for anti-resistance strategies. Working with Landseer, Systhane (myclobutanil) has also been fully approved for use on wine grapes. The rate of use of Systhane is, in our view, still rather low but activity can be enhanced using Potassium Bicarbonate.
Ripening is a little way off; growers should be vigilant and trap for Spotted Winged Drosophila (SWD) in order to understand the pest pressure on their own site. Following an application submitted by WineGB, an emergency EAMU (2995/19) has been granted for Exirel (cyantraniliprole). For more information on SWD, growers should refer to the excellent AHDB website or notes in the WineGB Green Book.
With the season being later than 2018, growers will be looking to enhance brix levels to facilitate a timely harvest. Leaf function is key here and the protection, nutrition and maintenance of the canopy is the best starting point.