At this stage, most are hopefully finished with shoot thinning and tucking and now are doing some remedial canopy work – such as fruit-zone leafing and canopy hedging.
Remember – intensive leaf removal is best done early (i.e. peppercorn to pea size berries at latest) in order to acclimate fruit to the radiation and temperatures experienced outside of the canopy. However, it is never too late remove fruit-zone leaves -this practice aids in air movement through the fruit-zone, which reduces drying time, allows better fungicide coverage on fruit, and ultimately aids in disease management. Given that fungal disease management is perhaps the most important focus of eastern US vineyards, fruit-zone management is of paramount importance. The pictures below show a cane-pruned Merlot vine in which two leaves were removed from the fruit-zone at about the pea-size berry stage. This fruit-zone is well-, but not overly-, exposed.
Shoot hedging is also of paramount importance at this time of year. One could remove fruit-zone leaves, but not hedge or trim laterals on the canopy, and the net benefit would be zero. It is not hard to imagine how the canopy on the left (pre-hedging) has greater leaf and fruit-zone shading and humidity buildup within the canopy compared to the canopy on the right (post-hedging). The canopy on the right will ultimately be in better shape late in the season when healthy foliage is required to ripen fruit. If left unattended, the canopy on the left will have a higher likelihood of developing downy mildew issues and late season fungal disease rots on fruit. Last, it is important to remember that once shoots are hedged and apical dominance is broken, lateral shoot growth will be induced (see data below collected from Sauvignon blanc vineyard this week showing that unhedged shoots have shorter laterals than hedged shoots). Thus, bi-weekly trimmings will likely be in order after the first hedging event – particularly if the periodic rain events continue.
On top of all of this, many are still within the critical time frame to manage fungal diseases on fruit. This spring is shaping up to be one in which folks are spraying in between rains (at least here in Georgia). Those who have been on top of their spray program will reap benefits later in the season when the ideal environment for fruit rots comes as a function of softening berries, increasing sugars, and decreasing acidity.
I would again encourage all to check Dr. Mizuho Nita’s blog regularly throughout the season and follow his advice: https://grapepathology.blogspot.com/
Good luck out there.