Week 9 (Aug. 12 -16th)

Grape berries grow at different rates during the growing season. Cell division is complete within a few weeks after fertilization, but cell expansion continues throughout the entire season. The process is represented by a sigmoidal curve, meaning that cell expansion begins rapidly, has a "lag period", and then finishes rapidly. During the lag period the plant focuses all of it's energy and resources to the development of root and shoots. Once these are established, the pipework and solar panels (or power and glory), the plant transitions to devoting all of its resources to expanding and ripening the fruit until harvest.

This further illustrates what is going on with the vine during the growing season. Notice how anthocyanin levels increase  after the lag phase. Anythocyanin makes the grapes red and sugar makes the berries sweet, however flavor compounds don't start accumulating until the berry has begun to shrink in size at the very end of the growing season. This is why growing grapes is tricky in northern climates. Early frosts sometimes determine when a grower must harvest even though grape quality (for wine flavor) isn't to its prime yet.

During this dry spell we need to water young vines with the "water wagon" on a weekly basis. Since they have yet to develop fruit, young vines devote all their energy to vegetative growth. This means that their roots and shoots are constantly expanding, so they need constant water supply. We don't want to over-water young vines, however, as this would encourage their roots to remain shallow in the soil. Shallow roots make vines more susceptible to drought and winter damage.

We are now constantly netting vines as they ripen their fruit. For the high cordon trellis systems like this we drape the net over the top, where on the VSP trellis systems we connect the top of the net to the fruiting wire. For both systems we cinch the bottom up and twist-tie it closed.

Check out the damage that occurs when the birds get to the grapes before we're able to net.

I was fortunate enough to cap off the week by volunteering at the fifth annual Cold-Climate International Wine Competition at the U of M. I spent the day opening bottles, pouring glasses, and carting around full and empty flights of wine to and from the judges. It was an exciting day, as us volunteers were able to sample the wines once the competition was complete. Not only that, we were allowed to bring home the "back-up" bottles of each non-medal-winning wine :)