Wine grape growers need to think ahead to the 2015 growing season
Battling back from winter injury with appropriate vine canopy management will get vines ready for the next growing season.
Vine canopy management decisions will vary a bit by location and cultivar, but for vinifera varieties in general, the goal this year is to get the vine ready for a good year in 2015. Ideally, we would like to see an ample quantity of good diameter canes arising from the base of the vine when pruning time comes around next year. In order to achieve this, many growing shoots must be maintained on the vine for the rest of this growing season. If only a few shoots are alive or are kept during suckering, the entire resources of the vine will be distributed into just a few growing points and the end result will be large diameter “bull” canes. According to Michigan State University Extension, these are not desirable for being the fruiting wood for 2015 because of poor production, hard to manipulate, and less cold-hardy than ideally-sized canes. Even though it will looks like a dense, tangled mess, keeping most of the basal and trunk suckers in place for this growing season is highly recommended.
There are a number of questions which come up in this situation.
How many growing points is enough?
We don’t have a particular reference to turn to for an answer, but the likely answer is “As many as you’ve got.” Consider an established vine in a typical year – it would be supporting the growth of 20 or more shoots along the fruiting wire, each bearing two to three clusters, and they still grow enough that we have to top hedge the shoots. In order to distribute the vine vigor well and avoid bull canes in this growing season, the target would be to grow at least as many shoots on the vine in 2014. If nothing is alive along the fruiting wire, then shoots from the base and trunk of the vine need to be kept in place. On vines where there are ample shoots, the selective removal of surplus shoots could be considered. At the research vineyard, we recently “cleaned up” the base of vines, removing shoots growing in errant directions and helping the retained shoots to grow upwards with twine loosely tied around the entire mass of shoots.
Should the fruit be removed from the shoots arising from the base and trunks?
De-fruiting the dense growth of sucker shoots would require a great deal of labor. Consider the pros and cons of this action. Leaving the clusters on will help control vine vigor and reduce the severity of the potential bull cane problem. Fruit maturing in this area of the vine will be difficult to protect from pests and diseases. Would this fruit end up being of harvestable quantity or quality, especially considering the difficulty of your labor force to pick it?