An unusually dry winter has caused concern across California.  Areas received less than 10% of their average rainfall in December, and virtually no rain has fallen yet in Napa Valley in 2012. 

This year’s La Nina season is clearly different from the others, and it is unlikely that we will be able to catch up to an average year even if we have above average spring rainfall.  California has not experienced a drought since the years leading up to and including 2009; let’s hope that we don’t have a return to drought conditions.

The upside of this is that we have been experiencing lovely, crisp sunny days and have been able to get a lot of pruning done.  Additionally, there has been less of a concern of fungal pathogens, such as the canker diseases Eutypa and Bot canker, that are dispersed via rainfall and can enter the vine through its pruning wounds. 

It is still recommended to prune as late in the season as possible when the spore counts for these diseases are lower.  If that is not possible, it is recommended to pre-prune cordon trained vines, by removing most of last year’s growth, and leaving 10-12” canes.  If an infection occurs, it will be cut out when the final pruning cut is made.  Pre-pruning speeds up the final pruning pass, and if a grower is delaying making this pass as long as possible, it may be essential for it to be quick, especially if spring rains are occurring as bud break approaches. Cane pruning is less susceptible to these canker diseases.  Regardless, all pruning wounds should be treated to prevent these diseases.

Pruning is the most critical practice in the vineyard for achieving vine balance.  Two few buds selected can lead to overly vigorous growing points that remain in a vegetative state and shade and do not properly ripen grapes.  Conversely, too many buds can cause a lack of sufficient vigor and the resultant vines will be overcropped and suffer from ripening and concentration issues.  Pruning can be quite technical and crews should be trained to adjust their pruning techniques on an individual vine basis.

Weed control is another winter practice; however, the lack of rainfall has led to little ground cover, both desirable cover crops and weeds.

The recent forecasts have storm systems dipping into our area the second half of the month.  Let’s hope we get some good storms in!  Better now than in the spring!