New Web Site for the Viticulture & Enology Extension Team, p 2
Sorbic Acid as a Preservative in Wines, p. 3
Lemberger, p. 3
New Winery Workshops, p. 5
Good Cellar Management to Avoid Microbial Spoilage, p. 5
Dealing With Winter Injury on Grapes, p. 8
Grape Disease Notes, p. 10
Upcoming Meetings, p. 12
New Web Site For The Viticulture & Enology Extension TeamA new web site (http://www.oardc.ohio-state.edu/grape) has been established for the Viticulture & Enology Extension Team web page entitled "The Ohio Grape Web". You will find several of the topics that were available at the old site are included, as well as several new hot links to other web pages. We felt that our grape growers and winemakers should have access to current and up-to-date information. You will find information on: insect and disease management, establishing vineyards, weather, survey results, Viticulture & Enology Extension Team members, calendar of meetings and events, Vine Grant Program, grape acreage report, Ohio State University Extension bulletins, ATF, OARDC Grape Branch, and many other important topics.
"The Ohio Grape Web" can be found at (http://www.oardc.ohio-state.edu/grape).
SORBIC ACID AS A PRESERVATIVE IN WINES I. GENERAL PROPERTIES
By Jim Gallander
Since several of our wineries use sorbic acid as a preservative in sweet table wines, it is important to have a good understanding of its main characteristics. Sorbic acid is widely used in many food products to control yeast and mold spoilage. This agent has a very low order of toxicity, and findings have indicated that sorbic acid is metabolized like other fatty acids to carbon dioxide and water. Sorbic acid is an unsaturated, six carbon fatty acid, which is similar to those found in edible fats and oils.
Sorbic acid and its salt, potassium sorbate, have broad-spectrum activity, mainly against yeast and molds. They are much less active against bacteria, and should not be expected to protect wines from bacteria spoilage or malolactic fermentation. This preservative works best below pH 6.0 and is relatively ineffective above pH 7.0. Wine pH values are usually within the range of 3.0 to 4.0, which is highly desirable for sorbic acid activity.
Potassium sorbate is often used to treat wines, because sorbic acid has a lower water- solubility. The solubility of sorbic acid in water is 0. 1 5%, by weight (20oC) as compared to potassium sorbate at 58.2% of 20oC. This salt is a white, crystalline powder and should be stored below 100oF and should not be exposed to moisture, heat, or light. Containers should be kept closed and away from cellulosic materials. Also, paper, cloth and other absorbent materials soaked with sorbates may ignite spontaneously. Both materials, sorbic acid and potassium sorbate, can cause eye irrigation. In case of eye contact, flush with water for 15 minutes and get medical attention.
In the next issue, we will discuss the use of potassium sorbate in treating sweet table wines. This will include the chemistry, levels and disadvantages of using sorbic acid in wines.
Lemberger by Andy Troutman
Note: Andy Troutman is the vineyard manager at The Winery at Wolf Creek, Norton, OH.
The 1998 harvest was extraordinary in many ways. In our vineyard, all of the varieties ripened unusually early, and in most cases, with extraordinary high levels of soluble solids. Rot was minimal and red varieties had magnificent color. Lemberger, was no exception, and is one particular variety that over the past several years exhibits these qualities annually.
Lembergers origin is disputed. It was derived from Vitis vinifera, which some ampelographers claim to be originally French. Some claim that it is a lost Gamay Noir clone. The greatest production of this variety is in Austria were around 6,250 acres are cultivated under the name Blaufrankish or Blauer Frankisch. Lemberger is also grown in the warmer parts of Germany as Blauer Limberger and in Hungary as Kekfrankos. The New World cultivation is centered in the Niagara escarpment of Ontario and the Yakima Valley in the state of Washington. A few plantings exist in the Finger Lakes region of New York and Virginia.
Lemberger, grafted on 3309C, was first planted in the Wolf Creek vineyard in 1994 on the recommendation of Canadian growers. Our vines are planted on a 9 X 5 spacing in a shallow Loudonville silt loam soil that slopes ~ 3% to the South. The vines (trained to a mid-wire cordon and vertically shoot positioned) are vigorous, upright and fruitful. In the past two years, the vines have been pruned to three node spurs, and depending on vine vigor, the fruit has been thinned to one or two clusters per shoot. Leaves around the fruit zone are also removed before veraison to improve fruit color. Lemberger breaks bud near the first of May, which is early compared to other varieties at our site. Compared to other vinifera, it has good disease tolerance and in only a few years has powdery mildew infections on leaves been observed. Veraison, in Chambourcin fruit, usually begins around the last week of August or the first week of September, and harvest begins around the last few days of September to mid October. Lemberger is generally harvested at the same time as Chambourcin.
Lemberger is fairly winter hardy compared to other vinifera in our plantings.
Cornell has determined -7.1 oF its median freezing temperature. From experience at our site I would rank it closer to the hardiness of Chardonnay. It is also capable of producing large yields, up to ten tons per acre in Germany and Washington, although five to six tons is probably more realistic. I believe (totally my opinion) this large fruiting capacity, and the vines high vigor can make up for a great deal of bud loss do to winter injury.
Perhaps, the main drawback is the name, Lemberger. There is potential for varietal excellence, unfortunately it is cursed with a name similar to a rather infamous cheese. The solution may lie in either reintroducing it under a new proprietary name or blending it with other wines. Perhaps the best solution is consumer education about the variety, and this may only occur if more Lemberger is planted and subsequently available on the market.
The wine quality of Lemberger is reportedly fair to excellent. Most examples are medium bodied with substantial approachable tannins, deep color, and medium acid. It is, however, made into a variety of styles. In cooler climates or in cooler years, much of it is turned into a light fruity early drinking red. In warmer areas, specifically the Yakima Valley, the predominant style is heavier, with some oak aging. Examples from Washington and even Canada have revealed Lembergers potential to age well if properly treated. Along with varieties like Cabernet Franc, it has some of the best potential for quality red wine in the region.
1. Kaiser, Karl. 1996. Lemberger, Zweigelt, and Dornfelder performance of little-known European jewels in Onatrio. In: Ohio Grape Wine Short Course Proceedings. p. 50.
2. Pool, Robert. 1993. Vineyard management. In: Vineyard and Winery Management. May/June. p. 60.
3. Robinson, Jancis. Vines grapes and wines. Reed Consumer Books Ltd., London. pp. 220-221.
New Winery Workshops by Roland Riesen
1. Wineries Unlimited, March 14-17, Lancaster, PA. Organized by Vineyard and Winery Management. For information call 800-535 5670.
2. Planning & Financing, Establishing & Expanding Vineyards and Wineries.
28th Annual New York Wine Industry Workshop, Geneva, NY, March 22-24.
For anybody serious about grape growing and winemaking I strongly recommend this workshop. Every year it covers pertinent, practical issues presented by top experts from industry and academia. It provides an excellent opportunity to interact with the Finger Lakes grape-wine industry, and visit vineyards and wineries to observe and discuss firsthand how this area has managed to establish itself in the elite of the grape growing and winemaking regions. At this years workshop the following topics are covered:
an overview of vineyard enterprises
developing a business plan
financing and other considerations in planning a new winery
site selection and pre-plant preparation site requirements
planting and training
vineyard design options
site selection and winery layout: sales, wine production, warehouse: separate or combined building?
planning for worker protection, worker safety
and much, much more!
Contact Roland Riesen, 330-263 3814, firstname.lastname@example.org for registration information.
Good Cellar Management to Avoid Microbial Spoilage by Roland Riesen
Ever had a sluggish or a stuck fermentation despite having added yeast nutrients? Ever wondered about certain aromas and flavors in wines, some good, some bad, some downright ugly, the origin of which you couldnt explain? There is a good chance that these incidences have to do with microorganisms (yeast and bacteria) used in your winemaking process. It is important to know the impact of these microorganisms and how to control them with your cellar management. Some of these microorganisms are important in winemaking and do not necessarily result in wine spoilage. There are many possibilities for negative and positive flavor modifications. Recent advances in research have shed some light on these issues. In this article I summarize the aspects of yeast in the alcoholic fermentation (1,2,3,4). In the next issue of Vineyard Vantage, I will address the microorganisms involved in the malolactic fermentation.
The Good - Desired Yeasts in Winemaking
To avoid microbial spoilage, strains of Saccharomyces cerevisiae or Saccharomyces uvarum must become dominant during the alcoholic fermentation. Both species reduce the likelihood of spoilage by other yeasts and by acetic and lactic acid bacteria. Dominant means, that other yeasts are, in contrast to previous theories, always present during the entire course of the alcoholic fermentation, but at a lower cell number thus reducing their flavor contribution. The winemaker has to create the most favorable conditions for the two preferable yeast species to dominate: moderate fermentation temperatures, preferably 60-80oF, high cell density at inoculation, favorable must composition, pH 3.0-3.4, no temperature shock before and after inoculation (no more than 4oC or 7oF change in one hour), moderate additions of SO2 (20-50 mg/L). Today approximately sixty strains of S. cerevisiae and two strains of S. uvarum (S6U and W15) are produced commercially. S. uvarum strains form 0.5 - 2.0 g/L more glycerol (increasing viscosity and mouthfeel) and as much as 200 mg/L more 2-phenyl ethanol (rose-like aroma) than S. cerevisiae strains. The impact of these substances is evaluated differently by different individuals.
The Bad - Yeasts That Can Cause Problems
Saccharomyces bayanus yeasts (e.g. Prise de Mousse [EC 1118]) have been popular for many years for use in sparkling as well as in still wines, and for the cure of sluggish and stuck fermentations based on their expectation of reliable, fast and complete fermentations through their fast dominance of the yeast population and their higher tolerance towards SO2 and alcohol. Recent research results however suggest that this practice maybe problematic. All commercial wine yeasts are glucophilic, which means that they use glucose faster than fructose. Sacch. bayanus yeasts are three to five times more glucophilic than S. cerevisiae thus decreasing the glucose to fructose ratio faster (metabolizing glucose faster) which can actually lead to sluggish and stuck fermentations! Therefore sluggish and stuck fermentations due to high residual concentrations of fructose are more successfully cured by S. cerevisiae or uvarum than by S. bayanus strains. However, stuck fermentations with high SO2 content (added by the winemaker or produced by the yeast) are better cured by Sacch. bayanus strains because of their higher tolerance towards SO2. The use of S. bayanus for alcoholic fermentations can also lead to problems with a desired malolactic fermentation (MLF). Dependent on the strain and the fermentation conditions between 20 mg/L and 60 mg/L SO2 is formed. This compares to 10 mg/L SO2 or less for S. cerevisiae or uvarum. The higher concentrations can lead to a much delayed or even completely inhibited MLF because Oenococcus oeni (formerly Leuconostoc oenos) are particularly sensitive to SO2 requiring 10 mg/L or less free and no more than 40 mg/L total SO2. In contrast Pediococcus (or the "ugly" bacteria) are more tolerant towards SO2. Remember also that the action of SO2 is pH dependent, being more inhibitory at lower pHs.
The Ugly - Undesired Yeasts in Winemaking
Indigenous (native) fermentations (fermentations without inoculation by a yeast starter culture) have caught renewed attention (and "caché") particularly among wine critics. The indigenous yeast flora is dominated by Hanseniaspora uvarum (or its imperfect [non-sexual] form Kloeckera apiculata) which can constitute up to 90% of the total population - independent of the wine growing region. Some of its strains are capable of complete alcoholic fermentations, even in grape musts which have been pasteurized! H. uvarum produces 20 to 70 times more volatile acid (acetic acid) than S. cerevisiae which can decrease the fermentation activity of the inoculated yeasts and lead to sluggish and stuck fermentations. Studies have shown that acetic acid in wines is mainly formed by indigenous yeasts, primarily H. uvarum, and never by bacteria such as acetic acid bacteria! These bacteria did not develop in grape must or later during the course of the alcoholic fermentation. The acetic acid can be transformed to its esters in the presence of alcohol. These esters can support the flavor of the wine but at high concentrations they can be objectionable. "Desired esters" are described as fruity, tutti fruity, bonbon, banana, pineapple, etc. "Undesired esters" are described as organic solvent, chemical, nail polish remover. If the ester concentration is too high the wines are considered sensorially defective. It is important to note that the ester formation is uncontrollable and unpredictable! Ester formation in wine has nothing to do with variety specific aroma! In addition the ester aroma is very short lived (from less than six months to one year). Hanseniaspora uvarum is always present in grape must. Therefore successful fermentations (indigenous and inoculated) are characterized by the dominance of S. cerevisiae very, very early during the course of the alcoholic fermentation. Favorable conditions for this to happen can be obtained by adding SO2 to the must at crushing, "clean" racking, warming the must to at least 60oF (15oC) before inoculation, a pH of at least 3.1 and the inoculation with an active selected starter culture of S. cerevisiae with a high cell density. Temperature shocks during the alcoholic fermentation have to be avoided. It is known that a decrease of 7oF (4oC) or more in one hour or less results in a drastic inactivation of the S. cerevisiae yeast starter population.
Even though everything "natural" sounds very appealing with an intriguing touch of romance, in winemaking it may lead to a decrease in wine quality. The grape growers and winemakers have it in their hands to create a favorable environment for the microorganisms to optimize wine quality, sensorial enjoyment and - financial return.
Gafner, Jürg. 1998. Microbial Stress Aromas. New York Wine Workshop. April 3-4. Geneva.
Gafner, Jürg. 1998. Reduced Sulfur Off-Odors, Fatty Acids, Esters, and Fuel Oils. New York Wine Workshop. April 3-4. Geneva.
Gafner, Jürg. 1998. Good Cellar Management to Avoid Microbial Spoilage. New York Wine Workshop. April 3-4. Geneva.
Riesen, Roland. 1992. Undesirable fermentation aromas. Proc. of the Wine Aroma Defects workshop. July. Corning, NY.
DEALING WITH WINTER INJURY ON GRAPES
by Dave Ferree, Maurus Brown, and Dave Scurlock
Thus far, we have enjoyed a mild winter with little bud mortality even on Vinifera cultivars. We had a long fall with many sunny days so the vines hardened and went into dormancy well supplied with carbohydrates.
All studies on grape hardiness emphasize the importance of ample tissue carbohydrates in helping vines cope with cold temperature. Carbohydrates are stored primarily in the roots, but important reserves are also stored in the trunk and canes. These carbohydrates are mobilized in the spring and are the building blocks for new growth. A portion of the reserves is used in respiration as the vines break dormancy. If reserves are inadequate due to excessive canopy shading, overcropping, drought or other stress, then there will not be adequate reserves available for early growth and development. Stressed vines dont harden properly and thus, wood quality is reduced and early winter temperatures can kill a greater proportion of each cane.
Thus, cultural practices that encourage a good canopy light environment result in an ample supply of carbohydrates that enhances cane hardening in the fall and vigorous growth in the spring. Many training systems such as the Geneva Double Curtain, Scott Henry, etc., improve light penetration in the canopy. Shoot positioning or leaf removal around the cluster promotes even distribution of light, particularly on the basal portion of the canes. Controlling insects and diseases that damage leaves also promote a build-up of carbohydrates that allow the vine to harden properly. Avoiding over-stimulation of vegetative growth through maintaining modest nitrogen levels, not applying nitrogen after June, and balanced pruning also foster the development of wood that can tolerate low winter temperatures. If nitrogen levels are too high or vines are pruned too hard, "bull cane" growth occurs which is less hardy than more modest growth.
If a cold temperature event occurs, how should you go about evaluating the level of injury that has occurred? Since cultivars differ widely in their sensitivity to cold damage, it is important to sample cultivars separately. Select canes that you would plan to retain as count wood from random vines throughout the vineyard. Allow the wood to thaw and remain at room temperature for several days before cutting. Buds are the most sensitive to cold injury and can be assessed by cutting at the mid-point across the bud. An uninjured compound bud will show the primary bud (largest in center), secondary and tertiary buds (smaller on either side of primary) as light green. They will be brown to black if killed by cold temperatures. If less than 20% of the buds have injury, no adjustment in pruning should be done. If 50% of the buds are injured, the number of count buds left after pruning should be doubled. You may want to use the following formula to adjust the number of buds that should be left if vines are winter damaged.
For example, if the normal count would be 30 buds, and you have 30% injury, the formula would be:
Adjusted Bud Count = Number of buds normally kept x 100
100% - (% of buds killed)
= 30 x 100
= 0.43 x 100
= 43 buds should be kept
If the cold event is more severe, then cane injury can occur. Often can injury is not visible until sometime in March when vines begin to deharden. Making a 2-3 inch cut removing the bark along a cane can be used to help assess damage. If no injury has occurred, the tissue should be bright green. Injured tissue will appear brown. Cane injury occurs because the cambium, which has tissue with active cell division occurring, is killed and since it is the only source of new xylem and phloem, no new tissue is generated. Cane injury is normally not uniform and additional canes are generally left during pruning. Often the best approach is to spur prune, as the basal buds are often more hardy than buds further out on the cane.
If the cold event is very severe, trunks and cordons can be killed. This type of injury is more common on young vines often on the southwest side of the trunk. Trunks may split when injured, but this doesnt always happen. Injured trunks are prone to the infection by crown gall, which often develops during the growing season following the injury. Since trunk injury is seldom uniform across the vineyard, one of the best means of lessening the impact is to have multiple trunks. When injury occurs, cut out the injured trunk and replace it with a shoot developing just above the graft union.
In summary, several cultural practices can be used to lessen the effects of winter injury. Cultivars known to be sensitive should be pruned last and hardy cultivars pruned first. If injury has occurred, spur pruning can be used as basal buds often survive. Good canopy management practices such as training systems that keep the canopy open to light and shoot positioning should be used to optimize carbohydrate levels and promote hardening in the fall. Crop load should be adjusted to vine size to prevent overcropping and carbohydrate depletion. Maintain good insect and disease control, which promotes optimum leaf performance. Nutrition, particularly nitrogen should be adequate, but not excessive. On cultivars prone to injury, multiple trunks and ample renewal spurs should be used to develop spare parts. With vinifera cultivars grown on rootstocks, hilling soil over the graft union is essential to preserve living tissue for regeneration if a severe temperature event occurs.
Although this has been a mild winter to date, we hope this review of how to assess and deal with winter injury is useful. It may help in selecting wood during pruning and in handling vines during the coming growing season to prepare them for next winter.
GRAPE DISEASE NOTES by Mike Ellis
Most grape growers are familiar with the new fungicide (Abound). Abound is the first of a new class of fungicides called strobilurins to be introduced for use on fruit crops in the
United States. Abound was first registered for use on grapes in 1997, but was first introduced and used widely by Ohio grape growers last year (1998). Although most growers are familiar with the use of Abound on grapes, I would like to briefly review its use recommendation prior to the 1999 growing season.
Abound is registered for control of black rot, downy mildew, powdery mildew and phomopsis cane and leaf spot. Abound is most effective against black rot, downy and
powdery mildew. Although it has activity against Phomopsis, it is not as effective as mancozeb or Captan for control of Phomopsis. Therefore, in the very early sprays for control of Phomopsis (one to six inch shoot growth), the use of mancozeb or captan alone is recommended (I prefer mancozeb). These fungicides are cheaper than Abound and more effective against Phomopsis. For wine grapes that are highly susceptible to powdery mildew, early season control of powdery mildew is critical. Ascospores (primary inoculum) for powdery mildew are discharged in the spring when we have one tenth (0. 1) inch of rain with an average temperature of 50oF. This can occur quite early in some growing seasons; Thus, early fungicide applications for Phomopsis must also provide control of powdery mildew. For these early sprays a combination of mancozeb at 3 lbs per acre plus Rubigan at 3 oz per acre is a good fungicide choice and is fairly economical. The use of mancozeb alone (on Concords or where powdery mildew is not a problem) and the use of mancozeb plus Rubigan on wine grapes (where powdery mildew is a problem) for the first two sprays of the season should be very effective.
The most critical time for controlling most grape diseases is from immediate pre-bloom through 2 weeks after bloom. I would like to see Abound start to be used during this period. The first Abound spray could be made around the initiation of bloom or shortly after, with a second spray 10 to 14 days later. Abound cannot be applied more than twice (2 times) without alternating its use with another type of fungicide. After two sprays of Abound, mancozeb plus Rubigan (the most economical) or mancozeb plus Nova or Procure should be used in one or two sprays (I prefer two) starting at 10 to 14 days after the last Abound spray. You can then switch back to Abound for another one or two sprays, if you wish. This approach to using Abound is expensive, but should result in excellent disease control on highly susceptible varieties.
It should be remembered that Abound can only be applied six (6) times during the growing season and has a 14 day PHI (can be applied up to 14 days before harvest). It may be wise to save one or two Abound applications for use later in the growing season for control of powdery or downy mildew on highly susceptible varieties or very late maturing varieties.
Abound is registered for use on grapes at the rate of 11 to 15.4 ounces per acre. The 11 ounce rate (with thorough spray coverage) should provide effective disease control when used on a 10 to 14 day spray interval. In university tests, the 14 day interval has provided good contact.
Remember that Abound is very phytotoxic to McIntosh or McIntosh related apples. If you use Abound in your spray tank, do not use the same sprayer on apples, even after the sprayer has been thoroughly cleaned. Obviously any spray drift from grapes to apples must be carefully avoided.
There are many strategies that can be considered for the use of Abound fungicide on grapes. The information provided above is simply intended to be food for thought. One important aspect of using Abound that should be kept in mind is fungicide resistance management. Especially for wine growers that have a long history of using the sterol- inhibiting fungicides (Bayleton, Nova, Rubigan or Procure), it is important to introduce new fungicide chemistry into the spray program to prevent or delay the development of fungicide resistance (primarily in the powdery mildew fungus) to these fungicides. Abound is a new class of fungicide chemistry and is ideal for this purpose.
As always, if you have any questions related to grape disease management and the use of fungicides, contact Mike Ellis at 330-263-3849 or E-mail: email@example.com for additional information.
New Strobilurin Fungicides
As mentioned above, Abound (azoxystrobin) was the first of a new class of fungicides (the strobilurins) introduced in the U.S. for use on fruit crops. Abound is a product of Zeneca Agricultural products. Other Agri-chemical companies in the U.S. are also developing this new class of chemistry and should be introducing other strobilurin fungicides in the near future. Sovran (Kresoxim-methyl) produced by BASF and Flint (Trifloxystrobin) produced by Novartis are two new strobilurin fungicides that could be registered for use on grapes within the next year (1999). They are similar to Abound in their spectrum of disease control on grapes. It should be noted that even though these fungicides are all in the same class of chemistry (strobilurins) they do differ somewhat in their spectrum of activity. This means that they all may have good activity against powdery mildew, but one may be slightly more effective than another. As this type of information becomes available, we will make it available to grape growers. If and when, these new fungicides are registered for use on grapes in Ohio, we will use this newsletter to inform grape growers as soon as possible.
March 22-24 In-depth Fruit School and 28th Annual New York Wine Industry Workshop Lakefront Ramada Inn, Geneva, NY. Contact Thomas Henick-Kling (315-787-2277) for details.Topic:Planning, Financing, Establishing and Expanding vineyards and wineries.
March 25 Ohio Grape-Wine Short Course Planning Meeting. Ohio Wine Producers Association is hosting a strategic planning meeting for the 2000 Short Course at the AmeriHost Inn off of I-71 on State Route 13 near Mansfield. RSVP to the OWPA phone: 440-466-4417 if you plan to attend.
Any information provided in this newsletter regarding procedures, products or equipment are provided solely for informational purposes and are not intended for advertisement and endorsement of any procedures, products or equipment, nor criticism of procedures, products or equipment not mentioned. The authors, The Ohio State University, Ohio State University Extension, and Ohio Agricultural Research and Development Center assume no responsibility for the implementation of procedures, products or equipment mentioned in this publication. Readers should follow manufacturers label for specified directions and recommendations.
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