Grapes Beginning to Ripen Sept 10, 2011

The grapes are starting to colour up and soften and the sugars are starting to accumulate.  Its the time of year to set the bug and/or bird netting out so the critters don't devour your grapes.  Visually, the vines are showing some signs of water stress, particularly the Ravat 34.  For certain I've over cropped the Ravat variety this year and some shoot thinning was required to help relieve some of the stress.  The vineyard has entered into a drought situation as there has been no usable rainfal since July 21st.  Usable rainfal is that which falls in such amount as to enter the ground and replenish soil moisture.  The only moisture the vines have access too is dew which forms overnight and settles on the leaves.  Long range forecast looks like a possibility of rain in about a week.

Analysis of the various varieties shows some are advancing to maturity faster than others, here is a list of average Brix measurements and observations taken on September 10th;
Lucy Kuhlman, Brix 12 - seeds turning brown, softening
Marechal Foch, Brix 10
Triompe D'Alsace, Brix 8 - *still irrigated
Colmar Precoce Noir, Brix 9.5 - *still irrigated
Leon Millot, Brix 11 -  seeds turning brown, softening
Ravat 34, Brix 7
Petite Milo, Brix 10.5 - softening
Cabernet Foch, Brix 7
Cabernet Libre, Brix 9

Lucy Kuhlman pictured below;

Leon Millot pictured below,

Ravat 34 pictured below;

Clearly the earlier Kuhlman varieties (Lucy Kulhman and Leon Millot) and Petite Milo are ripening the fastest.  Interestingly, Triompe D'Alsace and Colmar Precoce Noir are said to ripen even earlier then Leon Millot yet they are behind Leon Millot visually (skin colour and seeds) and by way of sugar accumulation.  However, the Triompe and Colmar have been provided regular irrigation and show no water stress.  Some literature articulates that deficit irrigation at veraison to harvest hastens maturity in grapes.  It is possible, and appears that the irrigation these varieties are receiving has slowed their rate of maturity in comparison to Leon Millot.