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Green Again! Vintage Update 3-6-2014

Much needed rain has replenished our soil moisture, reinvigorated our ground cover, and made significant contributions to the reservoirs and ground water supply in north coast vineyard regions.  However, this wet February has only partially alleviated the severe drought in California that began in 2012.  And, for the 2013 growing season, as an example, Oakville in the heart of Napa Valley, has received a little less than 14 inches of rain, which is approximately 55% of an average year’s rainfall. 

It is a relief for growers to at least begin the 2013 growing season with a full soil profile, as severe water stress at budbreak can cause root attrition and restrict vegetative growth.  Replenishment and water availability later in the season may continue to be a concern, and water conservation and efficient water use for viticulture need to be implemented.  Applying water at key phenological events, such as flowering, and before heat waves will be key to surviving a drought vintage.

The wet weather has warmed the atmosphere, and between the periods of rain, we’ve had plenty of sunshine.  This has caused one of the earliest budbreaks on record.  Chardonnay and Pinot noir have already begun to grow, particularly young vines and vines in warm pockets.  But, even later varieties such as Cabernet are experiencing bud swell.  Therefore, it is time to check wind machines and frost alert systems and prepare for what could be a long frost season. 

Growers who choose late pruning to delay budbreak and avoid frost, or to avoid Eyutypa, will need to finish pruning in the next couple of weeks.

Cover crops and weeds have germinated and grown with the wet and warm weather.  It is time to begin weed control.  Once the ground is dry enough to avoid compaction, mowing and cultivation should be implemented.  Early winter frosts damaged many cover crops, and this late wet weather has caused many weeds to grow.  This, coupled with the potential for low water availability later in the season, should lend some consideration to cultivating in permanent cover crops.  By cultivating, a grower can avoid competition between the cover crop and the vines for the scarce water.  Cover crops can be re-established in the fall, once the drought is over, or whenever the grower feels it is appropriate.

Welcome to Vintage 2014!

Vintage Update 1-17-2014- Time for a Rain Dance

Although sunny, 70 degree weather is glorious for enjoying the outdoors, it is a serious concern for the 2014 growing season.  Record drought has left many reservoirs unfilled, groundwater levels low, and has dried out soil profiles, causing cover crops to struggle at best. 


Some growers have been irrigating, and perhaps if water is abundant, you may want to consider that.  My feeling is that we want to get the soil profile full before budbreak, so beginning irrigation a few weeks before anticipated budbreak is a good idea.  Irrigating now is potentially not as strategic if irrigation water is limited, as the water will drain or evaporate and not be utilized by the vines.  However, as roots awaken pre-budbreak, it will be important to provide adequate soil moisture to avoid root attrition.

 

Prior to bloom will be another critical time to provide soil moisture.  If vines are experiencing a severe deficit at bloom, set will be affected and yields can be very low.

 

In addition to being thoughtful and judicious about irrigation, it is a good idea to consider other techniques that may reduce water demand or conserve water.  This may be a year to cultivate permanent cover crops to avoid competition with vines.  Many cover crop has been damaged by frost or hasn’t grown well so far this year, and this may be a year to consider discing it and replanting in the fall. 

 

Perhaps consider investing in wind machines in vineyards that use sprinklers for frost protection.  Although wind machines won’t help if temperatures drop too low, they will be useful when temperatures or close to or just slightly below freezing. 

 

Plan ahead to implement protocols to assess vine water status and availability since strategic irrigation is going to be critical.  Sap flow sensors will be useful to determine vine water status during the season, as will pressure chamber leaf water potential readings.  Neutron probes are useful, even now, to determine soil moisture levels and replenishment rates.

 

The bright side of all the dry weather is the ability to get a lot of pruning completed.  Eutypa and Bot canker are dispersed by rain and moisture, so presumably that should be less of a concern.  I still recommend some pruning wound protectant to heal the wound quickly and prevent the possibility of infection.  Click here to learn more about cane pruning and cordon pruning.

 

Stay tuned for more vintage updates, and let’s hope we get some rain for all of California’s sake!

 

Vintage Update 9-6-2013- Getting Hot & Heavy

The 2013 vintage heats up as the weather warms this coming weekend.  Many wineries in Napa are well into the white wine harvest, with Chardonnay and Sauvignon Blanc tasting great at higher than expected yields.  Pinot Noir harvest is also ramping up.  Many wineries have even harvested their first blocks of Bordeaux reds, especially from early blocks of Merlot. Word on the street is that quality is very good and quantity has been slightly or in some cases significantly above average. 

 

All of the warm and sunny weather we have had all year has advanced ripening so that vineyard blocks are being harvested a week or more earlier than an average year. The recent heat has increased sugar accumulation, but the cool nights have helped to retain acidity.  Peak phenolic development is delayed slightly compared to sugar accumulation so it is not surprising that winemakers waiting for phenolic profiles and flavor concentration may pick at higher Brix this year.

 

The heat has also compressed ripening across all vineyards and varieties.  The least ripe Cabernet that I work with hails from Howell Mountain and is already 22 Brix!  That means the wineries are going to be very busy in the next few coming weeks, and if the weather stays warm to hot, most grapes will likely be harvested in a compressed period the last three weeks of September.

 

The forecasted heat wave scheduled for this weekend into early next week is concerning.  There are a lot of grapes on the verge of maturity, where sugar accumulation (phloem transport) has slowed or stopped, and they are susceptible to shrivel.  Vineyards with underdeveloped canopies or row orientation that exposes grapes to the hot afternoon heat are very susceptible to heat damage at this time.  Irrigation, shade cloth and sprinklers can help mediate the risk if available. 

 

Even if grapes are protected in this heat, this intense heat is going to compress the ripening even more across vineyards and varieties.  Tank space, labor, and winery logistics are major challenges to a compressed harvest. 

 

This is the most exciting and most nerve-racking time in the vineyard.  The grapes are close to maturity, and anticipation brims for the harvest.  Vintners are excited about the quality, but nervous about getting all these grapes harvested so quickly.

Vineyard Update 8-13-2013- Harvest 2013- An Early But Slow Start

Harvest has begun in Napa Valley and the surrounding north coast viticultural areas.  Earlier lots of sparkling wine, lots picked for rosé, and some blocks of white grapes destined for lower alcohol wines have already been harvested.  The recent moderate weather has slowed ripening down a bit, and the harvest begins early, but at a slow pace so far.

 

Due to lovely weather during bloom, we had a uniform set in most blocks, and also experienced a uniform veraison.  The only challenge has been that as veraison progressed, some of the clusters most exposed to the hot afternoon sun during the late June/early July heat wave are showing delayed ripening and poor color development.  It is a good idea to remove these clusters, or the most exposed wings of the clusters, during the final green drop, which growers should be finishing up now in red varieties.

 

The color drop is an ideal time to remove clusters lagging in development. It is easy to create protocols.  As an example, if you only want to remove a small amount of crop as a touch up, which should be the case if you did the first thinning pass properly (removing most clumps, large wings, and fruit from weak shoots prior to veraison) then you can tell the crew to thin any cluster that is still 50% or more green when only ~5% of the clusters will qualify, meaning 95% of the clusters are 50% or more through veraison. 

 

If you need to thin more for contract or winery targets, or vines seem stressed and/or ripening is delayed, you can do this at 80% veraison, instead of 95%.  This is a good time to also clean up any crowded areas that have developed once berries have sized, by removing wings or clusters from the centers of the clumped areas.

 

Although we had a nice, uniform set, it looks like we will only have an average or slightly above average yielding vintage as the berries have remained small. Small berries are likely a result of the drought year, but this should be ideal for concentrated wines.  I don’t anticipate the vineyard yields to be as high as 2012 and less thinning was required in high end blocks.

 

It looks like it’s forecasted to heat up at the end of the week, so harvest may also heat up next week.  Right now, Napa Valley is brimming with positive anticipation!

 

To learn more about the start of the 2013 vintage, here’s a report on a Napa Valley Grapegrowers recent press harvest conference where I spoke with some of my colleagues.

Vineyard Update 7-19-2013- Harvest Approaches

Napa Valley’s vineyards endured an intense heat wave that lasted about a week and ended on the 4th of July.  The vines survived surprisingly well, with damage limited to very sensitive varieties like Petite Sirah, and vineyards that suffer from low vigor, with extreme sun exposure and little or no irrigation.  Although temperatures cooled from the extreme heat, we continue to have average or above average temperatures and long, sunny days.

This has brought us an early veraison.  Even in later blocks of Cabernet, we are seeing the first signs of veraison and some blocks are well on their way! 

Hopefully growers made their first pass at thinning, and are now planning for the veraison green drop.  After the first thinning pass, it is worth doing another cluster count, and perhaps cluster weights to see the impact of thinning and how cluster weights have increased since lag phase.  If you take cluster weights now, you will need to factor % veraison, prior historical harvest cluster weights, and observations on cluster and berry size to determine the multiplier used for final cluster weight. 

Getting an updated crop estimate will help determine how much additional thinning is desired for the green drop.  If you are at 4 tons per acre and have a goal of 3 t/ac, you will want to remove 25% of the clusters.  The crew can be instructed to enter the block at 75% veraison and take off the greenest clusters.  It helps to give them a target, such as 3 to 4 clusters per vine.  In some cases, thinning only a small percent of the clusters that are most lagging in development will make a big impact.  Remember that the more important thinning pass is the first pass during lag phase, since early thinning will make a bigger impact on accelerating ripening and enhancing uniformity, and require less thinning overall. 

Mildew pressure was high this year, but for those growers who are on top of it, they should be clean and nearing their last mildew sprays as berries become less susceptible to mildew after veraison. 

Once all the vines have been thinned, the main focus will be on judicious and timely irrigation to prevent shrivel and heat damage.  Some growers may use shade cloth in advance of heat waves.   Avoid excessive irrigation to maintain small, concentrated berries.

As we finish thinning, it’s time to get our cellars prepped for an early harvest!

Crop Thinning for Yield Management in High Quality Vineyards

A viticulturist's goal is to create vines that are balanced. One of the main balances in the vineyard is the balance between the vegetative growth and the reproductive growth of the vine. The vegetative growth of the vine includes the elongation of shoots, the development of leaves, and lateral shoot growth. The reproductive growth is cluster development.

With vines of low vigor, there could potentially be too little vegetation to ripen the fruit. Conversely, in high vigor situations, the clusters can be shaded and the vines continue to focus on vegetative growth to the detriment of ripening fruit. In both cases, the results can be underripe fruit. However in the lower vigor situation, the vines may also have overexposed fruit that shrivels due to sun exposure before the vines are optimally ripe, resulting in a mix of underripe and overripe flavors.

There are techniques, such as irrigation and fertilization that can be used to increase vine vigor in low vigor situations. There are also methods to reduce vine vigor, including withholding irrigation and fertilization, and using competitive cover crops. But, for a given level of vine vigor after shoot elongation has completed or once berry development is in the lag phase of growth, a viticulturist needs to decide the appropriate crop level for that vine.  This level depends on the quality goals of the viticulturist, as there is generally a correlation between higher quality and lower yields. Of course, too much thinning is a waste of money and can actually hurt wine quality if sugar accumulation outpaces other parameters of fruit maturation in a very low yielding vine.

Before determining the thinning protocol, it is important to get an idea of the crop by doing crop estimation. In some cases, there may be a target yield for the block that is created by the winemaker or winery contract in the case of fruit that is sold to another party.

Once you have an idea of the size of the crop, and how much you would like to reduce that crop, you can develop a protocol that is clear for vineyard workers to follow. One standard protocol that the industry commonly uses is to thin the crop based on the shoot length. For example, you may choose to remove all fruit from shoots less than 18 inches long, and leave only one cluster on shoots between 18 and 24 inches. Shoots that are longer than 24 inches can retain two clusters.

These length parameters can change depending on how aggressive you want to be. For example, if you want to leave less fruit, you can say that shoots shorter than 24 inches will have no clusters, shoots shorter than 36 inches can have one cluster, and shoots taller than 36 inches can retain two clusters. 

Even though carbohydrates can move throughout the vines and resources from larger shoots can ripen the clusters on shorter shoots, this type of protocol is still useful as a simple method for reducing crop on vines that have weak shoots, which usually indicates that they won’t be able to ripen a large crop. 

If shoot length is relatively uniform, but you want to reduce the crop by a certain percentage, you can choose to create a protocol to leave a certain amount of clusters per vine. For example, let’s say your average cluster count is 20 clusters per vine, and you are estimating that that will yield 4 tons per acre based on lag phase and historical cluster weights. If your target yield is 3 tons per acre, you can choose to thin to 15 clusters per vine.

For young vines, or vineyard blocks that are weak, you can choose to thin to one cluster per shoot. This is often done in very high-quality farming where the winemaker wants low yields, and is an easy parameter for workers to follow.  Short shoots should still have all fruit removed.  In cordon vines, another common parameter is to leave three clusters per position.  In a fruitful year, most shoots will have two clusters, and a cordon with two shoots per position would have nearly four clusters per position.  By reducing this to three, you will reduce the crop by approximately 25% and reduce congestion.  Be sure to have a good idea of the number of clusters per position and what percent reduction you will therefore achieve before implementing a protocol like these.

In some cases, the crop that set may be relatively in balance with the vegetative growth.  In this case, you may simply want to position fruit so it is all hanging freely.  This may require the occasional removal of a cluster in a crowded area, or the wing of a cluster in a crowded area. 

In fact, cluster shaping should be considered in very high quality farming situations.  If you keep a close eye, wings or tips of clusters may develop at a different rate than the majority of the cluster, and removing these parts of cluster can enhance uniformity and accelerate ripening of the remaining of the fruit.

Speaking of enhancing uniformity and accelerating ripening, another thinning pass is often suggested during veraison.  Once the clusters have achieved more than 50% veraison, you can get a better idea of final crop size and vine health.  If further adjustments are warranted, veraison thinning can be employed to remove the clusters that have not started veraison.  If you only want a minor adjustment, then thinning the 5% of clusters lagging in development at 95% veraison is an easy protocol.  For those wanting a larger adjustment, the protocol can be to thin the lagging fruit earlier, say at 80% veraison. 

Keep in mind that the later you thin the less impact you will have on the vine in terms of reallocating vine resources to enhance uniformity and accelerate ripening in the remaining fruit.  So, by thinning earlier, you can conceivably thin less!  By thinning early, you waste less of the vine’s resources that are removed by dropping crop and instead these resources can ripen remaining fruit and go to vegetative and root growth. 

As always, the extreme is not ideal.  Thinning too early is not a good idea, so unless the vineyard is very weak, you probably don’t want to thin fruit in high quality sites until you have reached lag phase and berries have completed their first phase of berry growth that is critical in determining final berry size. By lag phase, you can get a reasaonable crop estimate, decide how much to thin and don’t overdo it, which is a waste of money.  Also, thinning before lag phase can cause the vines resources to oversize the remaining berries, so using the extra crop as a sink during the first phase of berry growth can be beneficial in keeping berry size small for high quality vineyards.

As with many vineyard practices, crop thinning is an art and a science, a combination of intuition and experience.  Vine balance can be subjective to a degree, so keep in mind quality and economic goals when making your thinning protocol.

 

Vineyard Update 6-18-2013- Full Speed Ahead!

Lovely warm weather, with long days full of sunshine, has been the norm lately on the north coast of California.  The vines are loving it! 

 

It is amazing to see how quickly the vines have been growing this year, and we are a couple of weeks earlier than an ‘average’ vintage. Shoot elongation has slowed or growers have started to hedge, and the vines are shifting focus to berry development. Although cluster counts are high, and clusters are long and branched, set was not great in many vineyards particularly in Bordeaux varieties, and clusters tend to look loose.  Berry size looks like it could be large, based on the development we have already seen and the high seed counts. 

 

We are entering the lag phase of berry growth. The lag phase is a period of slowed berry development that follows the rapid period of growth after berry set.  The rapid growth after set is characterized by cellular division, and is a key determinant in the final size of the berries.  At lag phase, the berries are about half of their final weight, so it is a good time to do your crop estimation by counting and weighing clusters in each block. (See my previous post on crop estimation).  Lag phase ends at veraison, when the second phase of rapid berry growth begins.  This phase is characterized by cellular expansion, when berries fill with water and solutes. 

 


Lag phase is also a good time to do the first pass of yield adjustment.  Removing fruit from weak vines, weak shoots, and areas of congested fruit is a good idea.  There are all types of protocols, such as removing all clusters from a shoot less than 18” in length, allowing 1 cluster for shoots between 18-24”, and allowing 2 cluster for longer shoots.  Another option would be to take the total number of clusters down to a certain number of clusters per shoot or vine.  Thinning early allows the vines to focus on the remaining fruit, and on root and shoot development, which is particularly important for weak vines.  Early thinning of clumped areas helps because it is more difficult, and dangerous in terms of rot development, to thin once the grapes are soft and juicy.  Stay tuned for an upcoming post dedicated to cluster thinning.

 

This is also the time to adjust the amount of sunlight on the clusters if it hasn’t been done already.  Getting the clusters acclimated to sun exposure early will protect them during heat waves later in the season.  But be careful not to over-expose the grapes.  The weather has been trending hot and dry this year, and canopies are less developed due to drought conditions and a condensed growth period that led to many vineyards getting suckered ‘late’ in terms of shoot elongation.  Minimal leafing is recommended, only lower leaves and interior leaves from congested areas.  Most canopy work should focus on the removal of lateral growth, and even that is limited this year due to the lower vigor.  Leaving a leaf layer to protect the grapes is a good idea this year.  You can always remove it later if we get into a cold spell, but you can’t put it back on if we have a heat wave. 

 

Although early irrigation was essential in many vineyards to get sufficient vegetative growth, it is a good idea to impose a water deficit in the early phase of berry development through lag phase if possible.  This will limit berry size for higher quality winegrapes.

 

Vineyards are looking good, with a nice balance of moderate but not excessive vegetative growth and a potential for an average or slightly above average crop in most locations.  Let’s hope this weather stays nice and warm, and that we don’t have any extended heat waves.  That would make me, and the vines, very happy!

Vineyard Update 5-15-2013 Keeping Up With the Vines!

Record-breaking hot weather this spring has rapidly advanced grapevine maturation.  Bloom arrived a couple weeks earlier than average, and a few weeks earlier than the last few cooler, late vintages.  By now, most of the Napa Valley is blooming, with the later mountain Cabernet sites just starting to take off.

 

This condensed period of growth is a concern for vineyards that have not established enough shoot length prior to bloom. Judicious early season irrigation has paid off in building canopies in a record-breaking dry spring. Some fertilization has helped; I chose to fertigate my vines early with organic fertilizers, and some new, developmental blocks with organic fertilizers plus an application of a more concentrated synthetic fertilizer. 

 

Cordon vines are showing more uniformity of shoot length this year, while cane pruned vines have a higher abundance of short shoots.  In all blocks, but especially in the cane-pruned blocks, it has been helpful to sucker as early as possible.  Anything (early suckering, fertilizers, early irrigation) to help achieve the shoot length and canopy growth has helped this year!  Good luck finding labor though, as the labor shortage continues, driving up labor prices and making it hard to fill out labor needs. 

 

The demand for quick and early suckering has been challenged by windy conditions that have required early shoot positioning, pulling scarce labor resources away from suckering, especially in windy areas and in varieties such as Petit Verdot that are prone to breakage.  Some damage has been seen already from this dry, windy year.  But most importantly, let’s hope that the few early fires we had are not an indication of many more to come.

 

The shoot length and canopy development is even more of a concern this year due to the potential for a lot of grapes out there! In most vineyards, clusters are plentiful and often large and branched.  As we are blooming, the vines are already committing valuable resources into this extensive reproductive growth, and pulling resources away from canopy development.  This is essentially the opposite challenge from what we’ve had in 2010 and 2011, with wet springs causing excessive vigor and lower fruit production.

 

Every season brings its own unique set of challenges, and this one will do the same.  However, so far, if growers are on top of it, the stage can be set for a good vintage.  Ideally, we will have a good set (let’s keep our fingers crossed for continual good weather), and with the imposition of a timely and careful water deficit in the first phase of berry growth, we will produce lots of small berries, better for concentrated wines.  This will help us protect this highly scarce resource this year; a few deep early season irrigations should hold most vineyard for a while as long as we don’t have any heat waves. Growers should work on maintaining canopies as best they can without overirrigating, and then judicious thinning can achieve vine balance appropriate for canopy development. 

 

Weather has been perfect for the development of powdery mildew, so make sure to keep on top of it in your vineyard! 

 

We have plenty of time for ripening if the weather stays normal, as we are currently ahead of the phenological curve. Given the less developed canopies leaving fruit exposed and the current indication for continued warm weather, I would recommend minimal leaf and lateral removal in most blocks, at least until we know more.  Let’s keep these grapes protected.  Better to have a good set and too much fruit that can be removed by thinning than lose fruit at set or through sunburn or other issues.

 

Let’s hope the weather stays warm, but not too hot, and breezy but not too windy! But then…what would we have to complain about?

Vineyard Update 1-20-2013- Winter Work

After a wet December, the dry weather we have been experiencing this past few weeks has allowed us to get a lot of pruning done in Napa!  The deluge in December hopefully released most of the canker disease, such as Eutypa, spores, and the dry weather would reduce the incidence of infection.  Since it’ still January and there may still be high Eutypa spore counts, it’s a good idea to paint pruning wounds anyway.  A new sealant is available called Vitiseal that may have longer activity than B-lock.

With cordon-trained vines, which are more susceptible to Eutypa and other canker diseases, it may be beneficial to pre-prune. By pre-pruning, the vine may get infected, but the infection is removed at the final pruning when there are less spores in the spring compared to the early winter.   Pre-pruning can be done to keep the crews busy throughout the winter and avoid having too much work to do if a grower tries to late prune all of their vines.  At least by pre-pruning, the final pruning pass is quicker.

Now it’s time to start your under the vine weed control program.  The cold dry weather has stunted the growth of weeds and cover crop.  Additionally, many herbicides, specifically systemic herbicides, are not active when soil moisture is so low.  It may be beneficial to wait until some rain replenishes the soil moisture, if your weeds are not too tall to wait.  Before applying any pesticides, check with your local Pest Control Adviser.

An alternative, which happens to be compatible with this dry spell, is using under the vine tillage equipment. You cannot use this type of equipment if soils are wet or weeds are too tall, so this happens to be a good year to get your first weed control pass done mechanically. In vineyard that are not too steep or rocky, this can be a great, sustainable alternative to herbicide.  The technology has improved significantly and many types of tillers are available.  I have been using a new Gremagna, an implement that is like a small roto-tiller and is more effective than many implements that creates a relatively narrow width of soil disruption.

For more information on under the vine tillage equipment, check out my blog post here

As we prepare for 2013, we also are reflecting on the glorious 2012 vintage.  More notes to come soon on my thoughts on how those wines are developing in the cellars. Cheers!

Vineyard Update 10-19-2012- Seasons Change

With rain pending early next week, this will be the fourth consecutive vintage with mid or early October rains.  I cannot express how important it is to keep vineyard yields down and vine balance dialed in.  (Although too little fruit can be problematic too, when sugar accumulation outpaces other ripening indices and grapes shrivel more easily under the heat stress.)

 

After two stressful, low yielding and expensive vintages, it is understandable that growers welcomed the larger crop that 2012 produced. And although we have had a warm, sunny and dry growing season, heavily cropped Cabernet ripened slowly and is showing aggressive tannins and green seeds, along with a combination of underripe and overripe characters. 


Diligent thinning in the vineyard is really paying off now.  Those Cabernet wineries that aggressively thinned their estate vineyards and worked with growers who brought their yields down are naturally winding down their harvests now, without rushing and without feeling like we are compromising quality to bring fruit in before the rain.  The combination of a great growing season with low yields and fine-tuned canopy management allow us to get the hang time we need, but harvest earlier than many.  There are a lot of wineries scrambling to pick fruit right now and their fruit is not optimally ripe because it was heavily cropped.

 

At this time, as fall colors are setting in and harvest is mostly complete, the vineyard crews are winterizing the vineyards to protect them from erosion and establish cover crops.  An early season like this is beneficial for post harvest compost applications, fertigations, etc. because a still active canopy can take advantage of some additional resource uptake, and stimulate root growth. 

 

Wineries are still busy managing their fermentations, draining and barreling down red wines.  There is going to be a lot of big, bold, beautiful and sexy 2012’s!  This year is already showing a lot of ripe flavors and big tannin wines. Even the less diligent wineries should be able to produce good wines this year, and the top vintners should produce stellar wines. 

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