On this page we describe the annual tasks tending the vines and maintaining the structure that supports them. We cover
Pruning: cutting back last year’s shoots
Grafting: adding new cane buds (possibly from a different varietal)
Trellis Management: maintaining the structure that holds up the vines
Shoot Management: managing the individual shoots
Cluster Thinning: thinning out unwanted berry-clusters
We conclude this page with a note about Data Management.
Pruning is about cutting back last year’s canes to one or two buds where new shoots are expected to grow in the current season.
Since 2014 we prune in two steps – before we pruned in one. In the first round, in February, we cut last year’s canes down to 6-inch stubs. In the second round, in March, we cut the remaining stubs leaving a 2-bud spur on nodes around 6 inches apart. In both rounds, after cutting each row, we paint all cuts with a solution of Topsin M WSB (Thiophanate-Methyl Fungicide, EPA No. 73545-16-70506) by United Phosphorus to prevent infection with Eutypa. Following the second round, we spray the entire vineyard with Rally 60W to further protect against Eutypa. In 2015 we started using a new protectant Vitiseal Safecoat (by Vitisal International LLC, http://www.vitiseal.com/Home.html ), which proved to be more effective than the Topsin / Rally combination; it claims to not only seal but also fight Eutypa and other wood diseases and cankers. Rain spreads the Eutypa and canker spores which infect the cutting wounds. The two steps allow starting pruning early, beginning of February, while it still rains. Infections don’t invade the wood more than 1 inch per month; thus any new infection can be safely cut off in round two in late March. The following pictures illustrate the before and after step 1 and step 2
We learned about the hazards of Eutypa the hard way. In 2008 & 2009 we decided to prune the vines back more than before, but we did not know about the danger of Eutypa infestations when leaving large cuts exposed without protection. As a consequence practically every vine got infected. It took over 6 years to detect and cut out the bulk of the infected arms, and we lost over 50% of the fruit-bearing potential in 2010-2015 until new growth replaced what needed to be cut out. The following graphic illustrates the extent of the damage done by early 2013; it shows the percentage of Eutypa infected cordons cut out and replantings due to gopher and Eutypa damage. We continue to have to cut out infected cordons.
For pruning, we use electric pruning shears (Electrocoup F3010 by Infaco) as they make cleaner cuts and are less fatiguing than hand clippers. On completion, we chip all cut off
On completion of pruning it useful to reattach the arms to the guide-wire. I used a battery powered tying machine (A3M v2.0 by Infaco) for very loose ties of young arms in the past, but the metal wire turned out to be more harmful than useful. So now, I tie the arms with a plastic tie by hand or with one of the two tie-tools pictured on the right .
Grafting is about inserting a dormant bud into a cut on a live vine during late winter / early spring. The bud is encouraged to connect and grow into a new cane by pruning off the stem of the live vine just above the inserted bud. The primary purpose of grafting is to switch the clone or varietal of the vine.
We have not done any grafting yet, so no further info.
We deployed two different trellis systems: quadrilateral for the lower vineyard and bilateral for the upper vineyard. We started out with over-the-canopy nets deployed at veraison and removed after harvest. Because they are a pain to put on and take off, we replaced them with permanently installed side-nets in 2016-2019. The trellis also carries the irrigation hoses. So, altogether it’s a complex system of poles, wires, hosed and nets which takes a fair amount of upkeep. The maintenance is best performed after pruning when the vines are compact without shoots, and the ground is still soft.
Shoot Management is very labour intensive and covers a multitude of tasks:
Shoot Thinning: eliminating excess new shoots
Cane Positioning: positioning shoots vertically between trellis wires without crossing each other
Lateral Removal: removing secondary shoots which crowd the canopy
Leaf Thinning: removing leaves in the fruit zone
Hedging: limiting the length of shoots to 3-4 feet.
The goal of shoot management is an even and airy canopy with evenly distributed grape clusters each getting approximately the same exposure to the sun. Proper airflow limits mildew infections, uniform sun exposure helps all fruit to mature at around the same day (harvest day)
Our vines have very vigorous growth due to the choice of root-stock, the climate and the fertility of the soil. The advantages are that the plants can recover well from diseases and the many shoots provide more options for positioning; the disadvantage is that the vines need a lot of spring thinning and pruning because they produce far too many new shoots every year.
We start to shoot thinning in late April when the longest new shoots are ~ 2 feet. The goal is to eliminate all new shoots which are not positioned well or are deemed excessive for the ultimate density of grape bunches desired. We try to keep one spur with 2 canes every 8 inches. We further cut out all fruit on the small shoots which we do not expect to grow enough to ripen the fruit fully.
Thinning by hand is labour intensive and can often not be justified in commercial operations – the first round takes me about 45 hours for the lower vineyard. The following pictures show the before and after for a single vine:
This is also the perfect time to inspect the vine for Eutypa or “dead-arm disease”. The symptom to look for is stunted shoot growth with small yellowing leaves. Eutypa is a fungus which attacks the wood of the vine and ultimately kills the plant. Early detection and removal of the infected wood are essential if you want to save a plant. For more detail see this webpage: http://www.extension.org/pages/31525/eutypa-dieback-or-dead-arm-of-grapes, We had a lot of Eutypa in 2009-11 after we pruned the vines too aggressively without protecting the open cuts. Whenever any cut is made we now paint the open wound with a solution of VitiSeal which not only protects the wound (defensive) but supposedly also fights the already established fungi (offensive). The following pics show a typical progression of cutting out Eutypa
Cane positioning is about putting all canes between the guide wires, so they point up vertically and do not cross each other. We usually start in early May when the shoots have reached an average length of ~2 feet. Ideally, the first round is done before bloom so that the flowers don’t get disturbed by the abrupt movements and develop successfully into berries. The purpose of cane positioning is threefold:
first to create an airy canopy, so infections by powdery mildew are less likely, and spraying is more effective;
second to give all bunches approximately equal exposure to sun and shade, so the grapes develop more evenly; and
third to manage and equalize the length of each cane, again to manage balanced maturing of the grapes.
The first round of cane positioning takes me about 12 hours for the entire vineyard. We put the canes between the bottom guide wires which are then held together with C-clips.
As the canes grow, more rounds of positioning are required over the next 6 weeks to do the same with the middle and the top guide wires.
Lateral Removal & Leaf Thinning
Our vines have a lot of vigour which needs to be contained and channelled into producing optimal grapes. Earlier in the year, we contained growth by eliminating shoots which the vines pushed out beyond the 2 buds we pruned to grow new canes every 8 inches. Now we need to contain the growth on these canes we decided to leave standing. Unattended these canes will not only grow and carry 2-3 bunches of grapes and 10-12 leaves each to support them, but each cane will grow additional “lateral” canes at each leaf joint – and if not removed, each of these lateral canes would, in turn, grow to carry second tier bunches and leaves. So we need to pinch off all laterals at each leaf joint before they get big. Doing so opens up the canopy again for air circulation (which helps to prevent mildew), and it forces to vines to channel their energy to the primary grape clusters.
At the same time we eliminate all laterals, we continue with positioning the canes between the upper two guide-wires and we remove the first 2-3 leaves on each cane (up to and including the leaf opposite the lower bunch) to expose the grape bunches to direct sunlight which promotes tannin development and to prevent leaves getting tangled into bunches. The pictures on the right show a typical “before and after” on a single vine.
We start hedging when 50% of the canes have grown more than 2 foot beyond the top guide wire. Lateral removal is critical for effective hedging – if laterals had not been removed before, a cane which has been topped of would accelerate the growth of the laterals at each leaf node, and these laterals would grow secondary grape bunches. The consequence would be a very dense canopy with fruit of uneven maturity.
Lateral removal and leaf thinning are usually started in mid-May during full bloom. It is very labour intensive, taking me about 100 hours for the entire vineyard in two rounds. Hedging is a continuing effort until nets are put on because smaller canes continue to grow until they pass the ones that have already been hedged.
Grape & Cane Thinning
The goal of grape thinning is to optimize the quality of grape bunches that the vines are believed to be capable of bringing to full maturity. The final quality depends on the current state of the bunches as well as on the capacity of the vines to fully mature them. The weather year to date defines how much crop and what quality of bunches are available now; the age of the vines and the arms defines what amount of grapes the vine can expect to fully mature assuming average weather patterns during the remainder of the year.
Our target is to harvest 1.2 tons of grapes for our own wine production and sell the remaining crop to a local winery. We estimate that in a great season with mature, healthy vines throughout, the vineyard should be able to produce about 2 tons, or 2.7 tons/acre, of high-quality grapes. In an average year, we are happy with a harvest of 1.2 to 1.6 tons/acre. Eye-balling the current crop load and comparing that estimate to the target significantly influences how aggressive we are at dropping bunches at this time.
Our general rules for dropping bunches and canes are:
We drop bunches which have reduced or mediocre fruit set (i.e. not well developed or damaged fruit)
We drop all bunches on canes which are now less than 1 foot long (i.e. the cane would not have the capacity to mature the fruit). We also cut out the weaker of two canes on a node if either of them is less than a foot long (the idea is to focus the vine’s energy on growing what is needed next year).
We drop all bunches except the best developed on canes which are now between 1 and 2 feet long (i.e. the cane would not be able to mature more than one bunch)
We drop all bunches except the two best developed on canes which are now over 2 feet long, except for extremely strong canes which are allowed to carry a max of 3 bunches if those bunches are well separated in space.
We cut off pronounced wings on all remaining bunches (berries on wings tend to mature later rest of bunch)
Clearly, these rules have room for interpretation. The interpretation in any one year depends on how much excess fruit the season has produced to date and how much tonnage we want to drop overall.
The picture illustrates the health of the vineyard in early June 2013. It shows the average lengths of the canes for each side of each plant. Clearly the short canes are mostly on the young vines (which were replanted a few years ago due to gopher damage) or on the new arms (which grew to replace the Eutypa cut-outs)
At Veraison the grape berries turn from green to purple-blue as the chlorophyll is replaced with anthocyanins. This turning of colour provides an excellent opportunity to compare the maturity of the grapes across the vineyard. Ideally, veraison should happen for all grapes at the same time, but it does not – some turn colour early, others turn colour late. Because we will pick the matured grapes all at the same time, we end up picking grapes at different levels of maturity. To narrow the range of final maturity at picking time, it is advisable to drop the first 5-10% of bunches that have turned colour and, a couple of weeks later, drop the last 5-10% of bunches which are still green. Doing so should narrow the range of grape maturity left on the vine. This assumes that the early birds would not slow down their development and the late bloomers would not accelerate their maturing and catch up.
The following graphics show the progression of veraison in the vineyard from July 21 to August 4, 2013. On July 20 only 1% of berries show blue colouring. By July 26 that percentage increased to 20%. By July 30 60% of berries have turned and by August 4 the level of veraison has reached 86% on average.
Note, the development is uneven: the short rows and the east side of row 1 lag behind in development about 5 days. One potential remedy for next year is to start pruning the short rows first, before long rows (in 2013 we pruned from south to north).
The graphic on the left shows how veraison progressed in 2013. The mid-point at 50% veraison happened around July 29.
With veraison 90% complete, we start cutting out the remaining green grapes – green thinning so as get more even maturity for the remaining grapes at harvest time. The general rule is to cut out all bunches which at this point show no sign of veraison. The following graphic shows the crop load on each vine after grape thinning. The loads are graded 0 (for no grapes on the vine) to 8 (full grape load).
All plant management tasks are recorded in the database through the “INPUT: VineyardActions” – layout. Other than the date of the activity and the time it took to complete, we record no data except occasional commentaries. These tasks do not lend themselves to a lot of measurements. Here is a screenshot of the layout recording cluster thinning for August 20, 2018, in the short rows of the lower vineyard. Upon entry, the layout shows aggregate manhours spent on the vineyard blocks and for the task type.
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Last updated: December 28, 2018