California is experiencing its fourth consecutive year of drought. So far 2015 vintage is even earlier than last year, which is logical considering the faster heat accumulation recorded during the first four months of the year. Consequently dates of budbreak and bloom are on average 2 weeks earlier than 2014.
“More water and higher winter temperatures”
During wintertime (Nov. 1st– March 1st), vineyards in Napa actually received more rain than in 2014 (450mm in 2015 vs 350mm in 2014), setting the stage for a potentially larger canopy development.
Since budbreak, we observed a higher accumulation of rain water, higher than last year, leading to a relatively high soil moisture content during the rapid phase of leaf area development.
When comparing thermal time accumulation between Nov.1st and March 1st, there is 20 Degrees Days (base 10degrees Celsius) difference between 2015 and 2014. That means that we’re roughly looking at seven days ahead of 2014.
As a result of more elevated minimal temperature during the winter and higher soil moisture content, we expect a higher microbiological activity (i.e. potentially higher soil mineralization rate). This should lead to more favorable conditions for early plant nitrogen uptake compared to 2014.
This potentially will increase the photosynthetic activity of the leaf area when it gets fully active.
Given those preliminary results, and if conditions at set are still favorable, we could expect higher yields in 2015.
To be followed…