Tuesday, May 24, 2016

Green Pruning

So I wrote in a previous blog that I leave extra buds when we do the first pruning just in case the winter was harsh and killed off many of the dormant buds or in case we were to get a late spring frost. Leaving the extra buds provides some degree of insurance against these possibilities as there are more buds that could possibly survive and produce some grapes or even secondary buds producing a smaller crop.  However, if all the buds including the extra ones that I leave produce a good cane with proper flower clusters I would need prune off many of the canes to bring the extra canes back to a "normal" cane count in order to produce quality fruit that will ripen on time. (If I were to leave all the extra canes the vine would be over-cropped and be slow to ripen and may actually not winter well as the vine does not get enough time to shut down into dormancy before the cold winter hits).

So what is normal bud/cane count? I use quotations around "normal" because I'm not so sure there is a normal bud/cane count.  You'll often read documents that provide recommended bud counts to leave for various grape varieites.  For instance a document may say that for St. Croix to leave 30 buds for the first pount of prunings then and extra 10 buds for each pound of prunings after that to a maximum of 50 buds etc etc. Often these measures dont tell you all you need to know to make a proper determination like what if your vine has 8-10 feet of trellis length. While 10 feet is unusual, at 10 feet of trellis length the bud count I mentioned above would probably leave 5 buds per foot when the vine could probably grow best at about 6-7 buds per row foot. Variables that affect growth include soil type, the fertilizer, length of season, vine type, irrigation, training method etc., as all of these will impact what the optimum balance is between bud/cane count and quality fruit production. So while the bud retention counts per pound of pruning is a good method its really just an approximation - a place to start - then you'll have to tinker with it to determine what is optimal.

So getting back to green pruning - when I did the first dormant pruning in March I may have left 10-12 buds per trellis foot on some vines but in the end I only want to retain 6 buds per trellis foot.  So now it is late May and risk of frost is gone, bud break has occured, and the canes are all about in the 3-5 leaf stage. I can see what canes are healthy and what ones are not. Some canes may be stunted or have poor flowers or no flowers at all and others may be fine.  In doing the green pruning I want to keep the good healthy canes and prune away the canes that are stunted or with poor or no flowers. I'll prune away until I achieve the desired 6 canes per trellis foot. See the pictues below;
Good cane with 3 nice flowers

Poor (or No) flowers on a cane
Stunted cane with 1 flower cluster
Sometimes nearly all the buds will produce nice canes and flowers and the temptation is there to leave them and produce this great big crop, but as I mentioned before if you do this it will delay the ripening and may also cause the flowers to produce straggly poorly filled clusters.  The vine simply doesnt have enough nutirents or energy to get all the flower cluster to full production.  Also, if you are trying to use a long cane pruning style for your vines you will find that if you leave too many canes that they simply wont grow long enough for this style and they are not as winter hardy so they have a tendancy for greater die back in the winter.  This makes it really hard to employ a long can pruning styles.
These canes shown here are going to be thinned out a bit even though they are all excellent with great flowers. So while all these canes are great its not a choice of which ones are better than the others - in this case I'll prune ones away so that there is greater space between the remaining canes that will allow better sunlight exposure and air flow.

Thursday, May 5, 2016

Bud Break 2016 2-3 Weeks Early

Since weve been growing grapes at Arrow Lakes Vineyard the bud break usually happens 14-21 days into May.  So what happens is the earliest varieties are at full leaf stage (about 75% of the buds) and the later varieties are a few days if now nearly a week behind.  For instance Petite Milo is always the first to bud out and get to full leaf stage, Castel, Foch and Marquette are next followed by Vandal Cliche, Leon Millot, Ravat 34, Acadie Blanc, Evangeline and Triompe D'Alsace - in pretty much that order.

This year as of April 30th, several of the vines are at full leaf stage including Petite Milo, Foch and Marquette.  Castel is mostly there and Leon Millot not far behind,  The Ravat 34 are not yet with full leaf open and the same goes for Acadie Blanc.  The Evangeline and Triompe are the latest to get going and ironically both about the earliest to ripen - both these varieties are great for short seasons with the potential of late frosts.

The other good news is the vines are super healthy, best every for bud and cane survival.  For the main red varieites we have bud survival is probablt 95 % on Foch, Marquette and St. Croix and 85-90% for Castel and Leon Millot.  Bud survival on Ravat, Acadie, Petite Milot and Evangeline are all 85-90%.  Foresure the mild winter is a key here but so is the fertilizer that we've been providing the vines the past few years and in particular the irrigation supplied last year in conjunction to these things.

Acadie Blanc