Dr. Dave Miller Michigan Wine Blog
Fall is my favorite time of the year. Summer heat gives way to crisp autumn mornings with fog in the lowlands and bright, warm afternoons that were just made for football. Fall leaves, apples, pumpkins and of course grape harvest are all part of this wonderful time. Another part of fall is rain that sometimes lasts for days. The weather pattern that parked over the southern end of Lake Michigan for the last week of September this year is an example of just how cloudy, gray and wet it can be when the weather pattern changes from summer to fall.
I am often asked how the rain affects grapes and wine quality. A good question since we associate warm, sunny days with grape ripening. Is it possible to produce good wines from a rainy fall? The short answer is “yes”! We have produced some outstanding wines in challenging years. Witness the 2009 White Pine Reserve Riesling. It is a classic Riesling that was produced in one of the wettest, coolest years on record in Michigan – 2009. How is that possible? We know that leaves make sugar when the sun shines on them so what happens when it’s cloudy? In fact, leaves cannot handle all of the energy that they absorb in full sun. The chloroplasts in the leaves get rid of the excess energy through fluorescence at certain wavelengths, a phenomenon that can be measured with the right equipment. That being the case the energy absorbed by leaves on a cloudy day produces a fair amount of sugar. So grapes and other fruits can continue to ripen under cloudy conditions. Rain presents a different challenge. It promotes bunch rots and, vines take up water after a rain and it dilutes sugar and flavor in the grape berries. If there is any damage on the grape skin from any time during the growing season it can now become the point where the skin breaks as berries swell with water uptake. The work we do all summer long managing canopies to expose fruit pays off now. The exposed fruit dries quickly when the rain stops. Sunshine on berries actually kills fungal hyphae or the fibrous strands fungi use to penetrate fruit tissues and begin the infection process. When done properly the summer work pays off now by keeping the berries from splitting and preventing or slowing the onset of bunch rot. As long as the fruit is clean and there are leaves, the grapes can be left in the vineyard to continue ripening. The forecast is for sunny and warmer weather. That will allow the water to evaporate from the soil and from the berries. Now the processes of sugar accumulation and flavor development will continue. The cool conditions we have had so far help the fruit retain its natural acidity which leads to the distinctive crispness we all associate with Michigan wines.
So don’t despair that rain is in the air. While it’s not as desirable as a dry vintage, the conditions encountered thus far in the 2011 vintage are manageable with good vineyard practices. Give us some warmth and a little sunshine to dry things out and we will give you some great wines!
White Pine Winery will introduce the 2011 white wines in April 2012 so stay tuned.
Dave Miller PhD
October 2, 2011
Grapevine Canopy Management: The Key to Fine Wine at White Pine Winery
It’ hard to believe that it’s already August and more of summer is behind then ahead. If you look at the local vineyards it’s amazing how much the grapevines have grown in the last 4 weeks. The vines grow so much that we have to get into the vineyards now with work crews to perform what is called “Canopy Management”. Grapevine canopy management involves several operations designed to open the canopy and expose the fruit. The grapevine “canopy” is another word for all the leaves and shoots that make up the vine as we see it in the vineyard. Grapevine canopy management is another tool in our collection of Sustainable Practices. Sustainable practices are intelligent operations that reduce the need for pesticides and produce better fruit and wine (see my last blog on sustainable practices).
The first technique used in canopy management is shoot thinning. Shoot thinning reduces the shoot number per unit canopy length thereby reducing canopy density. In addition to reducing canopy density, thinning shoots also removes the clusters on those shoots. Excess crop reduces the aroma and flavor intensity in the wine. When a balance between leaf area and fruit is achieved the end result is a better glass of wine. Shoot thinning is actually done in mid to late June depending on the season and variety.
The second operation in Canopy Management is hedging the vines. This is done to remove any shoots that have overgrown the trellis and are hanging out in the row, shading the lower vine canopy. Once hedging is done the vine rows look like a formal hedge in an English garden with their beautiful recti-linear leaf canopies.
The last operation is leaf removal. In this operation a crew goes through the vineyard and pulls leaves that shade the grape clusters, exposing them to the sun. It may not seem like a big deal in the heat of summer but as the days grow shorter, the sun angle is lower each day and the nights are cool and long, the clusters need all the heat they can get to ripen. Think of a morning in early October when everything is damp with dew. Exposed clusters dry within minutes of the sun striking them. Clusters shaded beneath leaves may stay wet more than half the day. Wet, cool grapes are the perfect breeding ground for fungi that cause cluster rot. Removing leaves not only promotes fruit ripeness, it also reduces bunch rots by changing the cluster environment. As I mentioned in my last blog, Sustainable viticulture involves various enlightened practices, one of which is canopy management. By using the techniques of canopy management we reduce the disease pressure on fruit clusters thereby reducing the need for fungicidal sprays.
Doing the extra work to manage the vine canopies yields many benefits in terms of disease control and wine quality. Properly done, canopy management in summer makes for a better glass of wine at harvest and that my friends, is what it’s all about.
Dave Miller PhD
White Pine Winery
July 31, 2011
We are just beginning to release our white wines from the 2010 vintage. The 2010 Dry Riesling has intense aromas of Granny Smith apples and pear with mouth watering acidity for great structure. It is the perfect accompaniment to summer salads, jerk chicken or by itself in your favorite spot for relaxing after a long day in the heat.
Coming in August: 2010 Pinot grigio. I think Michigan Pinot grigio's are as good as or better than Pinot grigio from anywhere in North America. The 2009 was crisp and fruity with an austere edge created by the cool ripening conditions that year. 2010 was a much warmer year and the wine shows this. Loaded with Pinot grigio's classic honey dew melon and pear aroma's and flavors, the 2010 is soft but still shows the crisp acidity that makes Michigan grigio's so classy. Another great white to enjoy ice cold after a long, hot day at the beach or touring the countryside. It pairs perfectly with local perch or planked whitefish.
We'll keep some cold for you!
Sustainable Vineyard Management at White Pine Winery
6 July 2011
Dave Miller PhD
Owner / Winemaker White Pine Winery
I am often asked the question by customers if we plan to go organic in our vineyard production system. It’s an excellent question with an interesting answer. The idea of producing grapes and wine organically is certainly attractive. Using only naturally occurring substances to control fungi, insects and weeds and minimizing the impact we have on the environment is a noble idea and seems to make sense. It must be less expensive, right? The reality in southwest Michigan is, without some of the commercially available compounds to combat fungi on foliage and fruit, we would not have a wine industry. The reason is we simply have too much humidity – in the form of rain and good old high humidity – for natural fungicides to work. A study was done on Long Island where Chardonnay grapes were grown organically. The vines not treated with synthetic fungicides lost 75% of their crop due to bunch rots making the remaining 25% of the fruit extremely expensive. High fruit cost equals high wine cost. Can you imagine paying 4 times more for your favorite Michigan wine so it can be produced organically? Even if consumers were willing to pay the higher cost there is still no guarantee that the grapes would ripen to acceptable levels for wine production before rot sets in.
So if we can’t produce wines organically in an economically viable way, is there anything we can to minimize the environmental impact of our vineyard operations? In fact there is and we do everything possible to promote what are known as “Sustainable Practices”. Sustainable Practices or sustainable viticulture is a common-sense approach to managing vineyards that reduces the environmental impact of the operation and, in many cases, the carbon footprint as well. Let me demonstrate how sustainable viticulture works with an example. In the old days a grower would add as much as 200 pounds per acre of actual Nitrogen (N) to a vineyard to promote vine growth. The growers often applied the N in April because they had time on their hands before bud burst or the start of growth. The vines typically performed well and everything seemed fine. As concerns about the environment grew in the 70’s and 80’s people started questioning long-standing traditions such as the timing and amount of N application. Research showed that vines typically begin taking up N around bloom or in late June. That meant that applying N in April gave up to two months for the N to leach through the soil into the groundwater or volatilize from the vineyard as a gas before the vines actually started to absorb it from the soil. The amount in the soil when the vines needed it was greatly reduced from the originally 200 lbs / acre. Further work also showed that vines only needed around 40 to 60 lbs of N per acre depending on the operation and the amount of crop removed from the vineyards every year. So growers began adding just the right amount of fertilizer to their vineyards (i.e. around 40 lbs of actual N) in late May to early June. The vines continued to be healthy, the growers saved lots of money on unnecessary N applications and there was less N leaching into the groundwater, running off or volatilizing.
Nitrogen fertilizer requires large amounts of energy to produce so using less reduces the carbon footprint of the operation. An added benefit of proper fertilization is that the vines don’t grow excessively. Nitrogen promotes vigorous growth in plants including grapevines which can lead to dense leaf canopies. An over-dense vine canopy makes it difficult for pesticide sprays to reach the clusters of grapes. It also shades the grapes from the sun which is the most powerful natural fungicide known. When fruit is shaded from the sun it not only is more likely to develop bunch rots but, it doesn’t ripen as well and makes a poorer quality wine. So by simply reducing the amount of N applied to vineyards growers reduced the impact on the environment and set their vines up to produce better wines. That is a sustainable practice in action. There are many other sustainable practices that use similar common-sense approaches to vineyard management such as monitoring forecast models to predict when certain diseases or insects infestations are more likely to occur. I’ll write more about those in future blogs.
At White Pine Winery’s Sophie’s Vineyard we have only used Nitrogen fertilizers during vineyard establishment and to replace N lost to grape harvest. After a small crop year we add no fertilizer. So when you savor your next glass of Riesling or Pinot grigio from White Pine Winery or another local producer you can rest assured that the growers and vintners are doing all they can to minimize the environmental impact of their operations.
Replanting Vines Maintains Wine Production for Years to Come in White Pine Winery’s Sophie’s Vineyard
6 June 2011
Dr Dave Miller
Springtime brings so many things – relief from a long, cold winter, anticipation for warm days, cookouts, swimming, camping, hiking, biking, open windows at night, no school for those climbing that ladder. For those of us in agriculture we see the promise of another crop. In the wine business we think in terms of “another vintage” and hope that each year will produce stunning wines that will be the envy of the world. The source of each vintage is the grapevines growing quietly in the vineyards. If anything happens to the vines then we won’t have grapes for winemaking, which brings me to my point: vine replants.
In Sophie’s vineyard on our property near Lawton we grow Riesling, Cabernet franc and Regent. The vines were planted in 1999, the year our daughter, Sophie, was born hence the name. Since then we have lost some vines to various maladies and it was really starting to reduce the production potential of the vineyard. To make matters worse there was a problem called “Crown Gall” that was in some vines a few years ago and was now spreading through the Riesling block. I decided to pull the trigger and remove all the affected vines and replant this year. Now you may think that replanting Riesling is as simple as calling a nursery and ordering Riesling vines. In fact it is much more complicated than that. To begin with, the scion (as the upper part of the vine is called) is going to be Riesling but there are a number of Riesling “clones” from which one might choose. Each clone has specific characteristics in terms of growth, cold tolerance, growth habit, cluster morphology, and, most importantly, wine quality. Each of the clones has been isolated from vineyards primarily in Germany and verified as being different from other clones of Riesling. Each of the clones is propagated by cuttings of one-year-old wood and so they are clones in the truest sense – they are identical to the original, mother vine. What is fascinating is that Riesling first appears in the literature in Europe in the 10th century. So the vines we are growing today are direct, clonal descendants from those vines grown hundreds of years ago. The same is true for all of todays grape varieties – Chardonnay, Merlot, Pinot gris etc. although few of today’s varieties date back as far as Riesling. Today’s Riesling clones are sourced from the Geisenheim institute which maintains mother blocks of hundreds of varieties and their clones. In the US we all plant materials originating outside of the country must pass through one of three plant quarantine stations run by the USDA. The main quarantine for grapevines is at UC Davis in California. UC Davis maintains a program known as the Foundation Plant Service that certifies grapevines are a) the correct variety and clone; b) free of virus and bacterial disease, and; c) available as propagation wood for nurseries in the US. They maintain a website called the National Grapevine Registry that is the source for information on grapevines in the US and one of the best sources world-wide. Check it out at http://ngr.ucdavis.edu/ .
All grapevines with European parentage (Vitis vinifera) must be grafted to a rootstock. That’s why we differentiate between scion and rootstock. The rootstocks used protect the vines primarily from a root pest called Phylloxera. The rootstock also influences the vines growth or “vigor”. There are many commercial rootstocks available with varying characteristics but that’s a topic for another blog. Selecting the correct rootstock is extremely important for the success of the vineyard. Keep in mind that we typically want a vineyard to bear fruit for at least 15 years and it takes four years to get the vines into production. With that kind of a time commitment we want to be sure everything is done right the first time.
Getting back to my replants for this spring, I called an excellent California nursery, Vintage Nurseries, and ordered Riesling clones 239, 198 and 110 on Couderc 3309 rootstock. The salesman informed me that they were sold out of Riesling 239 for this year – not unexpected as it makes superb wine. I was also informed that all of the vines on C3309 rootstock were sold out. Shoot! That’s why I usually like to order a year in advance. However, there were vines of Riesling 198, 110 and clone 90 on 101-14 Mgt rootstock. That is my next choice of rootstocks as it’s from the same parents as Couderc 3309. I placed my order and we planted the vines May 29th. Young vines require lots of TLC to help them grow big and strong and that’s exactly what they will get. I can almost taste the wine now….
Now we can insure full crops of Riesling for years to come. As I worked in the vineyard I looked at the young shoots growing and thought, “This is going to be an excellent vintage!”
p.s. Check out Riesling at the National Grapevine Registry and you can begin to get a feel for the world of grapevines out there. ( http://ngr.ucdavis.edu/)