All posts by Pietro Buttitta

These are very brief but serve as a good reminder to get ready for bud break, familiarize yourself with potential sprays, and get to know the Gubler-Thomas mildew model which can help indicate times of high pressure. Mildew lives all around us in the environment and is impossible to eradicate, so at best we keep it at bay until the grapes reach about 12 brix and become immune. A wet early season (like last year) increases the chance of infection, and spray intervals may need to shorten to keep up. It doesn’t hurt to go look at leaves and berries with a magnifying glass!

Oh, and if you don’t want to spray for mildew, plant hybrids like Baco Noir and Lenoir that are mildew resistant due to domestic grapevine genes. I have had some really tasty Baco Noir from Sonoma County recently.

As we start getting closer to harvest, it is a good time to review berry sampling, and how to get the most representative samples possible from your vineyard. In the attached video Chris Chen walks you through the steps, but to summarize, you need at least 50 different berries (preferably 100) from 50 different bunches (preferably 100) and from within different zones on each bunch. Some from the sun side, some from the shade side, some from bottom, middle and shoulders. Grapes on a single bunch can vary by up to 5 brix, so you want to equalize it out. Also don’t wait until the end of the day, it is best to sample at the same time you would be picking!

Also, I was playing with the idea of an informal winemakers meeting to go over possible winemaking decisions and what the options might be for those who are making their own wine. If there is an interest, just let me know. – Pietro

We are entering the period when your canopy growth starts to slow (keep an eye on those shoot tips for an indicator) and then the vine switches to fruit ripening rather than producing leaves to feed sugar to the fruit. It is critical in this period to keep an eye on water stress. In a perfect world you would not need to apply water until the berries have fully sized up and formed hard seeds, or even better until veraison, but steep hillsides, thin soil, stressed vines, and many other factors will change that. Some of you may even need to apply a little drip now, though we shouldn’t go too crazy with the water until the vine is firmly working on maturing fruit rather than growing leaves and longer canes.

This article posted by the Lodi Growers Association is a great overview with pictures to help remind you what to watch for and what your vines may be thinking about right now. The season has been pretty gentle so far so things should be looking good, but water stress, mildew control, and canopy control are the three fundamental things we need watch for a healthy crop. Please walk your vines often and communicate with your crew if you see anything mentioned in this article. – Pietro

RIPENING PERIOD STRESSES: RECOGNIZING THE ONSET & MINIMIZING THE IMPACTS – PART ONE

Hi everyone, Pietro here with a couple vineyard and winemaking topics. Now that your vines are growing and we have had a few warm days you should be seeing some real growth happening. This is a reminder that you should be spraying approximately every two weeks (more often in wet or foggy locations) to control mildew, which grows whenever the temperature is between 70 – 85F. You should also be suckering the trunks of the vines while the suckers are soft and snap off easily – I buy a 10-pack of cheap gloves with rubber palms for this, and then move up to your fruiting cordons or canes and shoot thin those as well. If the suckers become too large, their removal damages the vine with rips and tears that leave exposed wood for diseases. Here are a couple pictures borrowed from Penn State and Lodi Winegrowers:

On to the technical stuff! Last week UC Davis held a presentation of current research topics at Greystone in St. Helena on both winemaking and viticulture research. I highly recommend attending these meetings since they are affordable and quite interesting. There will be one on June 4^th at the legendary Oakville growing station focusing on vine growing which is linked here. I would attend if I could, perhaps you can catch a ride with Bill Saupe. Below is my summary of the presentations from last week.

1. Red Blotch – This is something we have in our Lake County vineyard that is spreading throughout California. A link has been established to native California grapevines which suggests that it has been here all along. It is spread by TCAH (Tee-ka) otherwise known as the three-cornered alfalfa hopper. The hopper does not travel far and lives mostly below the canopy in ground cover, but moves up to feed. 

The challenge is that there is a 3-year latency period from the initial vine infection. So if you are seeing that characteristic red-leaf all of a sudden, you were probably infected three years ago, and it has spread. We have vines in Lake County that came with red blotch as dormant grafts due to bad nursery practices, and it is spreading through insects.

Davis now recommends pulling individual vines if a singular isolated example shows up, but if two or more are present, they recommend pulling all vines within a 30’ radius and replanting. There is no known cure, and the vine decline is variable in speed. We have vines that top out at about 22 brix (photosynthesis shuts down) but I feel that they still contribute to the final blend. At some point they no longer will, and disease spreads in the meantime. Pulling vines is hard.

• Sensory evaluation – Many of us taste wine in barrel and sometimes create blends on the fly, this is part of the business. The key is knowing what sensory threshold you are bad with and making sure you have someone with the opposite tasting profile when testing. For example, 50% of the population can’t smell “rose” (b-damascenone) in wine, and the sensory threshold ranges in the 50% that can smell it by 100,000x!!! I am sensitive to VA but not some brettanomyces byproducts.

The big takeaway for me was a reminder of how important a reference standard is, which means first that when tasting with others we need to agree on what our words mean first off, for example consumers often confuse acid and tannin, and many will say a wine is “dry” when it is actually sweet but tannic. For ourselves as winemakers working on blends or questionable barrels, an easy trick is to compare with another sound bottle. For example, if you are trying to work Merlot into a tannic Cab within a Bordeaux framework, you really should pop open a benchmark Bordeaux-blend bottle, verify that it is sound, and use it as a springboard for comparison. We all get tunnel vision, whether in the cellar, at a wine competition, professional tastings or other critical tasting moments, especially in a room filled with barrels and bad lighting. Set yourself up for success and fight cellar palate by knowing your own blindspots. Tasting in threes is a good policy as well. Every blend, like every dish, gains something and looses something when blending. It could be something measurable like acidity, or the story of a vintage, and tasting with a few colleagues with different sensibilities and a shared language is helpful.

• Smoke – We all have measurable smoke in our 2020 wines. I have it in my Lake County wines and the nearest fire was much farther away than Lamorinda had it. In fact, I tasted it in all the 2020 Lamorinda wines with the wine panel. A few new compound families have been discovered, and new synergies between low-levels of compounds such as fruit masking have been verified. In tests fresh smoke only needs ten minutes to absorb into a grape berry next to a fire. Of course, our challenge was long, low exposure to smoke that had diminished compounds. Further complicating low-level exposure is the human factor due to a taster’s sensory threshold (yes many scotch drinkers don’t notice smoke) and specific enzymes within saliva. Also limiting skin contact beyond fast whole-cluster white winemaking doesn’t do much since more smoke compounds have been discovered within the grape pulp much more rapidly than previously thought.

The general guidelines if we have a fire-year still hold the same though. Assuming the fire is more than a few miles away you have choices like just making white wines, avoiding toasted new oak barrels or chips, minimize pressing, leave a little sugar which keeps some of those compounds bound, or build a red so big that it “floods the zone” with other flavors so that smoke is suppressed as a sensory experience. Also, grapes vary wildly in their susceptibility with Petit Verdot, Mourvedre and Pinot Noir being very sensitive, Sangiovese and the high side, Cab and Merlot are medium, and some cultivars like Barbera are strangely low. It has no correlation to skin thickness, and the science is still out on how the bloom helps in the process. In their tests they found smoke compounds within the pulp after just 20 minutes, way faster than previously thought, and pre-veraison grapes are still susceptible!

• Soil minerals – An ongoing study measuring identical Pinot Noir clones and roots planted across seven different regions. This is essentially a how-do-we-get-terroir study, and indeed since minerals act as enzyme cofactors, different fruit expressions seem to result as well, as much as weather can be eliminated as a factor. Obviously limiting other environmental factors is a challenge here. Minerals also have a strong influence on a wine’s reduction/oxidation potential as we know, and very mineral wines can be highly reductive as Clark Smith has been saying for decades (read your Postmodern Winemaking book, then use the knowledge for different goals) with very different expressions and needs. This study is ongoing, but unfortunately has some very strange parameters, so we will see what and how useable the end results might be.

In fact this is a topic I want to explore in the future for Lamorinda when we finally get monthly winemaker tasting together – I have done a few in Napa where we bring a bottle that we like and a “problem child” bottle and discuss, it is hugely interesting. How can we get a longer mineral finish into wine is the holy grail from my perspective, and a next level to reach for us, and this is a viticultural issue first and foremost with increasing mycorrhizal fungi growth in the roots. This can take us into topics like organics, weed control, mineral availability and all sorts of questions we need to spend a day discussing…

• Native California yeast strains – The topic of “natural” or spontaneous (uninoculated) fermentations continues. Yeast do breed and cross in nature. A large study has found a few interesting things, the first being that native oak trees are reservoir and incubator for saccharomyces yeast. The second is that a massive wine yest gene experiment has found that there are three clusters that have appeared consistently, one cluster is a huge family that isn’t particularly strong on oak trees, a second cluster is our inoculated strains which are mostly European isolates/selections, and the third cluster is the evolving interaction of these two groups, leading to an arguable California oak-derived synthesis of native and European yeast! This family is growing and evolving rapidly in winemaking areas.

This kind of cool (or dangerous) as yeast evolve rapidly, and native oaks are acting as a giant petri dish that may have some local terroir residue. 

Much of this research also looked closely at Twomey fermentations in their two winery locations nearby. Of interest, what they found in the second half of the fermentations as the wines go dry, is that the “in-house” cultured yeast – and they had particularly strong cultured yeasts like EC-1118 and Uvaferm 23 present in the cellar, in fact did not carry out the bulk of the work in fermenting to completion. The spontaneous ferments had a 1 or 2% population of these strong commercial yeasts, but in fact it was these hybrid local yeasts and spontaneous actors that did most of the heavy lifting, and had significant effect in DNA analysis. The price was a little more VA, and the big question remains of how much sulfur gives a level of security and how much destroys the native yeast mix. Some people go spontaneous but add 50ppm SO2, which is pretty much guaranteed to incapacitate most of the delicate spontaneous yeast and stuns everything until in-house sacch. yeast takes off, while 20 ppm is a common “soft” approach, mostly to suppress LAB, though wine pH and temperature are hugely important, as well as fruit quality. There can also be a moment of fear when your carefully maintained and barely-starting ferments go through an ethyl acetate day, which is produced by many of the wild yeast living on grapes. More damage = more sulfur or some other microbial inhibitor.

One last interesting yeast point, AMH yeast was used as a control, and the spontaneous ferments all went faster than the AMH fermentations. I have had trouble with AMH when it conflicts with another yeast strain since it is very sensitive and can go supernova as it fights it out with a stronger foe. That this particular yeast strain is indeed so slow is a usable bit of info for winemakers if you want a real low and slow inoculated fermentation – I love my slow 20-day ferments for Italian-style big reds. Just don’t mix it with other more vigorous strains.

• Pietro

(I wrote up a little vintage report – hope you enjoy and find something discussion-worthy. I would love to chat at some point with everyone and see your vineyards! – Pietro)

What a difference a year can make. In the span of just a few years we have gone from the notion that all California vintages are pretty much the same to the feeling that no two are alike. The Lamorinda AVA in Contra Costa county is fortunate to sit between two competing climate forces in the cooler Berkeley and Oakland Hills/Eastern Bay area to the west with water-influenced temperatures including fog and some volcanic elements, and the warmer inland Contra Costa AVA to the east that has its own unique diurnal pattern. Through the abundant small valleys running every direction in Lamorinda, the maze of aspects and slopes helps to crystalize unique terroir pockets through nearly exclusive hillside viticulture. Cooler spots to the east can still achieve ripeness with good afternoon sunlight, cold air drainage and warmth for reds, while warmer spots to the west enjoy evening cooling and wind that can moderate daytime high temperatures. It is an AVA in which almost any cultivar can perform well in and there is still a vast amount of exploration to do.

But first, some data from the last three years using Rutherford as a proxy for Lafayette. Rutherford is not as hot as Calistoga or St. Helena, and not as cool or Bay-influenced as Oakville, . The numbers for Healdsburg/Windsor as Chalk Hill or easter Russian River Valley, Rutherford, and the Lafayette Reservoir tend to be roughly comparable, so that is what is used below on the temperature charts.

Looking back, 2022 was a very strange year after the almost rainless 2021 that was awarded the driest year on record for the Northern California. The crop was also pitifully small in the North Coast. 2022 had pretty good rainfall, a moderate budbreak with unusually warm temperatures in the Spring, but into August it was running abnormally cool and almost two weeks behind, and there was a lot of work being done to choke back canopies growing vigorously from late rain and to keep mildew at bay. We were settling in for a cool vintage. Then at the start of September a record-breaking heatwave hit for a week touching 118F in many areas, followed by heavy rain (2+ inches) in many locations that put the vines back into a growth cycle, further degrading fruit quality despite a blissfully perfect ending to the season. There was much internal discussion on the destruction this level heat caused to grape chemistry, and some wineries won’t release 2022 wines. Here (I hope these temperature maps upload) is what that temperature curve looked like:

2022 Growing degree days (GDD) approx.: 3200

In 2023 things changed again with one of the coolest and latest vintages on record, bolstered by heavy rain in the winter that pushed crop load upward. Disease pressure was extreme with mildew and botrytis a constant threat without temperatures above 85F to suppress it, and mildewed grapes were refused all over Sonoma County, and high VA fermentations were a problem everywhere. The Lamorinda AVA fared well since hillside vineyards are naturally limited in their water availability, and the leaner canopies lowered the disease threat along with the AVA’s  abundance of grapes with small clusters and lack of heavily-cropped white grapes. All those valleys also promote airflow which is always helpful with mildew pressure, and though temperatures were low there was a good amount of hangtime, allowing ripeness to build slowly with moderate sugars, and good weather through October was just what was needed.

2023 Growing degree days (GDD) approx. 2700

But 2024 was a different story all together yet again, and very unusual. Much like the scorching 2020 vintage that had similar heat which was evidenced by fires throughout the state, the 2023/24 winter had heavy rainfall, well above normal in many areas with fully loaded soils. It came out of the gate hot and fast, and as the grapes approached veraison most growers in Lamorinda were already watering regularly and we were seeing lots 100F days. Some areas in Lamorinda touched 100 degrees over 40 times, and though one heat wave has become the new normal, two in late season, especially back-to-back AND in October is extremely unusual. However, there is also a subtle fortunate feature that has not been mentioned in vintage reports thus far – the evening temperatures were actually a little lower than normal relative to the daytime heat, creating a moderating effect that helped the vines recover, especially in Lamorinda.

2024 Growing degree days (GDD) approx. 3700

Viticulture: Overall Lamorinda grapes did very well for a challenging vintage. Canopies were mostly filled out thanks to good rainfall, though this can be limited by steep hillsides, and good rainfall helps continue root growth in the spring leading to stronger vines. The grapes in cooler areas such as Moraga and Orinda had it a little easier, but even hot vineyards looked good, though the constant heat stress made for a state-wide light crop. The double heat whammy in late September and October was stressful, and during the second spike in October some saw their fruit increase one degree brix per day, but despite some acid softening and low nitrogen, grapes that had been take care of made great wine with ripe fruit and good structure. When you have two heat spikes, there is only so much you can do.

Vineyards that did not fare well generally had either mildew problems, irrigation issues, or improper netting. Despite the heat (mildew does not grow above 85F) we still saw quite a few vineyards that had fruit damage due to early season mildew. This was a very wet spring which is always challenging, possible issues due to shading and proximity to trees, insufficient spray application (which is very hard to do by hand in all of these tractor-less steep vineyards) or not rotating chemistries, like using sulfur, then an oil, and then biologicals or strobilurins. Mildew creates microscopic holes in berries, which creates all sorts of problems, and it can be seen as grey or black specks on the fruit and in the clusters on stems, or mold-like spots on leaves. It has a musty, white pepper smell as well. It is always present and grows between 70-85F and without full sunlight, we just keep it at bay with most sprays. Some growers experienced heavy insect damage, but this was likely due to improper mildew control early in the season or predation. Some mildew in May easily leads to perforated sugar-filled berries in August that insects can smell, and that grape sugar in broken berries or on stems that have had the grapes pulled off send out a feeding beacon to all sugar-loving insects and even birds, not to mention sugar that ferments and then turns into vinegar and all sorts of microbial mayhem. Sound fruit should not experience any insect issues if the birds are kept out, but once berries are broken, it will all go downhill rapidly.

If one thing was clear for late season grape growers (Cabernet Sauvignon and in cooler pockets) it is that once you are behind on irrigation, it is impossible to “catch up” again. Drip irrigation can help keep vines stay a little more comfortable during a heat event, but it is impossible to apply enough water to negate the heat. A second heat spike only compounds this, especially with vines are at the end of their cycle when they just want to sleep. On this topic growers are advised to always watch the 10-day agricultural forecast, make sure that vineyard managers have checked all irrigation lines and that all controls are working properly, and visually check and confirm the system is functioning whenever possible. Coyotes love to chew through drip lines, hose ends can blow off, sun exposure can crack risers, and all sorts of problems can appear from nowhere. Hillside drip irrigation does not allow for much soil penetration either, so while your friends in Rutherford might get away with 4 gallons per week per vine in the last month before picking, you on a hillside will need far more, possibly 15 gallons per week per vine leading up to harvest. Remember that we are largely on sandstone and clay here, which has limited water-holding capacity depending on the amount of clay in your particular vineyard, and organic matter is hard to build in these hills, so holding onto the drip is a challenge. Former seabed ironically doesn’t hold much water, especially on steep hillsides, and I have noticed a few vineyards with the wrong rootstocks for hillsides (101-14 in particular) which will require even more water. Planting vines close together (most plantings are very close in Lamorinda) requires even more water to boot compared to wider distances between vines. The thinking on tight vine planting has changed a lot in the last 15 years.

Lamorinda is also unique in the necessity of bird netting. With so much beautiful woodland surrounding the vineyards it is also a paradise to birds, skunks, foxes, ground squirrels, deer, turkeys, and every type of animal that also loves sugar-rich grapes. Tightly secured netting is a must, but before the netting goes up at veraison, the canopies must have all the final work and tuning done first, meaning that final shoot thinning and any fruit thinning (not too much of a problem on hillsides) all needs to be done before the nets go on during or immediately after veraison. Walking the vineyard to check irrigation lines and check netting closures are always a good (and relaxing) idea.

There also a predominance of spur pruning in the area that makes for an interesting topic. Some cultivars like Syrah and Sauvignon Blanc are usually cane pruned, and in Bordeaux most Cabernets and Merlot are cane pruned as well in their wetter climates, but I have yet to see a single cane-pruned vine in Lamorinda. If you suspect trunk diseases like eutypa, or any sort of disease-related decline in your cordon arms, it may be time to gently go back to creating a new arm from a cane. Though many diseases generally come from neighboring vineyards which is not a problem in Lamorinda, the woodland also harbors fungal pathogens. The last 10 years a wealth of information has been published regarding a new understanding of vine pruning that prioritizes protecting the vines and building them for resilience that is worth investigating for vineyard owners who want to get their hands dirty. Wetter/cooler spots like in Orinda might want to consider the viability of cane pruning if disease pressure is a constant problem. You can even go half-and-half to experiment.

Winemaking: Unlike the record heat spike in 2022 that destroyed color (anthocyanin) in grapes on the vine by cooking them in place before they were even 21 brix, it did not get hot enough for that to happen in Lamorinda. Vines can tolerate quite a few days around 100 degrees if they have had some acclimation, and since Lamorinda is a solid zone 3 in general though there are exceptions on either side, vines will usually not be shocked by heat. Grape chemistries proved to be as unique as each person’s vineyard this year, but in general acids were as expected with some low-ish from the heat but some just right, tannin ripeness was great and nothing was noticeably off. There were some late-season picks that had perfect numbers, and a couple early ones that needed a little work, so it really comes down to the owner keeping a vigilant eye on everything and a communicative crew with an expert on board to react in a timely manner to the growing season, plus the general health of the vines.

The largest challenge for us at the winery in this hot year was receiving hot grapes. If the grapes arrive over 75 degrees we might have a problem. Fermentations want to start around 60-65 degrees for red wines and hopefully cooler, and colder for whites. Please do not pick grapes after 9am on a hot day. That fruit needs to arrive at the winery cold, the colder the better. I am used to meeting the pickers to start at 4 am and using headlamps. With bird netting make that 3 am. With hillside vineyards where every picking tub must be carried up and down a hill by hand, make that 2 am. Yeasts and bacteria are always present and they grow exponentially with heat, so keep those grapes as cool as possible, and keep them out of the sun once picked!

One other anomaly was that a few vineyards with great looking fruit had peculiar sulfur issues before fermentation had even started, which may have been from molecular sulfur remaining on the grapes. If you suspect that your vineyard team is only using sulfur for mildew suppression or are still using sulfur after the berries have sized up or into veraison, you should have them rotate to something else from the list above. Residual sulfur dust can be particularly terrible in fermentations, and micronized sulfur can be a problem as well. If used as a later-season spray in tight-bunch cultivars like Petite Sirah, Grenache, Petit Verdot, Sauvignon Blanc, and sometimes Pinot Noir, you run the risk that as the berries expand to full size the sulfur can become trapped between the berries, leading to problems down the road.

With the heat it is inevitable that grape nitrogen may be a little low, and some shrivel is inevitable with extreme heat. There were a couple vineyards that came in with challenging numbers in early September. They already had high sugars, high malic acid, and high potassium and pH, meaning three winery challenges at once. These are probably traceable back to lack of water leading to vine shut down early on, and possible overexposure to sun. If you have had a few years with some sunburn or challenging numbers at pick time, let’s take a look and see what we can do.

The wine business in general: For the second year in a row wine consumption has fallen by over 10%. The Central Valley continues to remove vineyards, grape contracts everywhere are broken, and wine tourism continues to decline. I had colleagues picking up Napa fruit that was usually $8,000+ per ton for $1,000 in October. Here in the Lamorinda area we are somewhat insulated from the urban anti-alcohol movement among young consumers, and many feel that we may have reached to bottom of the decline, which would be great. Though the WHO is not going to change their anti-alcohol stance, regime change in Washington is throwing all the cards into the air once again with a mix of tariffs, possible deportations, and FDA revisions (your food pyramid and dietary guidelines including alcohol are all on the table in 2025) that will all affect the wine business deeply on way or another.

All in all, Lamorinda had a great vintage despite quite a few challenges this year. Back-to-back heat spikes is no joke, and it is possible that pest pressure was extra high this year as the ebb and flow of wildlife and insect interaction seems to fluctuate with each vintage these days. Be sure to give yourself a big pat on the back. If there are things you would like to improve upon, please discuss things with your vineyard manager during the winter, well before the vines start growing. Winter is the time to plan any changes and discuss what worked and what didn’t. I would also personally love to visit everyone’s vineyard in person and I’m happy to offer any thoughts or help in any way I can. Understanding the vineyards helps make better wine, which will only help the AVA as it continues to move forward.

Pietro Buttitta

Thal Vineyards/Local Vines

Prima Materia Vineyard & Winery

info@prima-materia.com