Ough and Ingraham (1) conducted a study to test the yeast-inhibiting properties of potassium sorbate in sweetened wine in the presence of adequate levels of sulfur dioxide. Using a white wine, they reported that inhibition of yeast growth and fermentation was found at relatively low levels of sorbic acid (80 ppm). These results are slightly lower than those used in most commercial wines. The discrepancy might be explained by differences in wine pK alcohol concentration, level of microbial contamination, and yeast strains. Therefore, the recommended levels of sorbic acid in most table wines are generally within the range of 100- 200 ppm. With these levels, it is important to use an adequate level of sulfur dioxide and use proper vinification procedures to reduce yeast populations, such as filtration.

Since potassium sorbate does not contain 100% sorbic acid, it is essential to know the percentage of sorbic acid in this salt. On an equivalent weight basis, potassium sorbate has about 75% of sorbic acid. Therefore, higher amounts of potassium sorbate are required to obtain the same activity of sorbic acid. The following equation may be used to calculate the amount of potassium (K)-sorbate for treating wines.

Wt. of K-sorbate = Y x 3.8 x 1.34 x Z 1000

Where: Y = Volume of wine in gallons

3.8 = Conversion factor to change gallons to liters (L/gal)

1.34 = Conversion factor to change sorbic acid to K-sorbate

Z = Desired ppm (mg/L) of sorbic acid to be added

1000 = Convert mg/L to gms/L

Example: For a 125 ppm sorbic acid treatment, calculate the weight of K-sorbate to be added to 500 gallons of wine.

Wt. of K-sorbate = 500 gal. x 3.8 L/gal. x 1.34 x 125 mg/L 1000

BATF rulings indicate that finished wines shall contain not more than 300 mg of sorbic acid per liter of wine. In the next issues, we will discuss the disadvantages of using potassium sorbate in treating sweet table wines.

1. Ough, C. S. and L.J. Ingraham. 1960. Use of sorbic acid and sulfur dioxide in sweet table wines. Amer. J. Enol. Vitic. II: 1 17-122.

 

 

We are pleased to offer a workshop devoted to wine analysis by various laboratory techniques. One must not underestimate the importance of precise laboratory analysis in the production of a sound quality wine. It is essential that you utilize laboratory procedures to their fullest potential. This I 1/2day workshop is designed for winery personnel who would like to improve their testing procedures to ensure the production of good quality wine. In addition to the laboratory sessions there will be short lectures given on specific topics that correlate wine making and laboratory analysis. Adequate time will also be given toward answering specific questions.

Location: Department of Horticulture & Crop S6ence OSU/OARDC, Wooster, Ohio

Topics: pH, Titratable acidity, Brix

Free & total sulfur dioxide (Ripper method) Alcohol, Malolactic fermentation

REGISTRATION: Fee $60 per person. This fee includes: refreshments, laboratory analysis manual, laboratory use of equipment and chemicals, and other required items. Due to the amount of laboratory space available, the number of persons attending the workshop is limited to 16. There is still some space available at this time.

Registration will be accepted on a first-come-first serve basis. Pre-registration was required by May 10, 1999. However depending on availability, you may still be able to reserve a reservation by calling or e-mailing Todd Steiner or Roland Riesen at the OARDC by May 14, 1999.

Contact: Todd Steiner, phone: 330-263-3816, e-mail:steiner.4@osu.edu

Roland Riesen, phone: 330-263-3814, e-mail:riesen.1@osu.edu

In my last story about Lemberger I made several mistakes about Germany's wine geography. Fortunately Dr. Thomas Henick-Kling from Cornell University, a native from Baden Wiirttemberg (!), was kind enough to provide me with the correct answers and additional information about the state's viticulture.

The main cultivation area for Lemberger is the state of Baden-Wurttemberg (and not Wiirttemberg) with its capital Stuttgart (and not Baden-Baden, which is famous for its spas). There is no Lemberger planted in the winegrowing area of Baden, but it's the second most widely planted red variety after Trollinger - which is almost red - in Wurttemberg.

-10,000 ha (24,000 acres) of vineyards (1 993) with 18,500 growers producing 1 .4 million hi (37 million gallons) of wine oust over 5011/c red; Germany: less than 20% red).

-nearly 85% of wine is produced and marketed by cooperatives.

-35% of wine is sold through grocery stores, 30% through wine stores, and 35% direct to restaurants and private customers.

WHITE WINE PRODUCTION:

- 25% Riesling, 2,375 ha (5,700 acres), largest acreage of all grape varieties.
Soil: deep Keuper soils. Average Brix (1998): 19.

- Kemer: Trollinger x Riesling, appr. 1000 ha (2,400 acres), developed at Staatliche Weinbauschule Weinsberg.

- Muller-Thurgau, 950 ha (2,300 acres).
Soil: deep fertile soils. Average Brix (1998): 17.5.

- Slivaner, 475 ha (1,140 acres), matures 10-14 days before Riesling.
Soil: shallow soils of Muschelkalk and Keuper, on Kocher, Jagst and Tauber rivers. -

- Gewurztraminer

- Rulander (Grauer Burgunder, Pinot Gris), very little acreage.
Soil: warm deep soils.

- Muskatteller, very little acreage.

With a new growing season upon us many of you have already applied your first fungicide application to protect new growth from overwintering disease inoculum. This is also the time to begin scouting vineyards on a weekly basis for insect pests. The following list contains a brief description of the major grape insects as well as the approximate time of the year they are active. For additional information on control recommendations, or more detailed descriptions of the insects themselves, see the following bulletins. The Ohio Commercial Small Fruit and Grape Spray Guide (Bull. 506 B2); Insect and Mite Pests of Grapes in Ohio (Bull. 730); Grape Production, Management, and Marketing (Bull. 815). These bulletins are available through your local Extension office. You may also contact us at the Department of Entomology, OSU/OARDC, phone:330-263-3725.

Activity Period Pest

April-June Grape flea beetle - Small metallic blue beetle about 3/16 of an inch long. Adults feed on grape buds and foliage. Scouting for the adult beetle should begin in April and continue through May. Larvae are present on the under side of the grape leaves in late May and early June.

May-July Rose chafer - A straw colored beetle about 1/2inch in length. It is present in areas with sandy soil. Adults emerge in late May and early June at the time of grape bloom. They feed on grape blossoms, young fruit and foliage. Adults are active until early to mid-July.

May-Aug. Grape berry moth - A small mottled-brown colored moth with a bluish gray band on the inner halves of the front wing. The overwintering generation emerges in late May and June. These adults produce a new generation, which takes flight in July and August. Pheromone traps are recommended for monitoring this pest. This is the number one pest of grapes in Ohio. Larvae are capable of inflicting severe damage to maturing grapes and also facilitate the spread of bunch rot.

May-Sept. Grape phylloxern - This small aphid like insect causes galls to form on the underside of the leaf surface. The first galls usually appear when shoot length reaches 10 to 12 inches, Early season control of this pest is crucial. Once they are well established on the foliage control methods are usually futile.

July-Sept. Japanese beetle - The adult is a shiny, metallic green and coppery brown colored beetle that feeds on the leaves of cultivated and wild grapevines. Thin leafed cultivars are especially susceptible to defoliation by this pest. Adults are active from early July till frost.

June-Aug. Grape root borer - The adult is a clear wing moth about 5/8 inch long. The body mimics that of a wasp, brown with yellow markings. Adults begin emerging in late June and early July with adult activity lasting through August. This pest is easily monitored with pheromone traps.

Changes in Ohio Vine Grant Program by Maurus Brown

The Ohio Grape Industry Committee has concluded the selection process for the 1998 Vine Grant recipients. At this time, the OGIC is reviewing the overall application procedure to determine what changes should be made to improve the process. All of us are very excited about the implementation of this program to help encourage the establishment of new wine grape vineyards in Ohio. The Vine Grant program provides a good incentive to grape growers to expand wine grape production in Ohio. This will help reduce the dependency on external wine grape sources.

The OGIC has a target of 15 new acres to be established each year under this program. Growers must follow the program guidelines to qualify for Vine Grant funding. As in the past, the Extension Viticulturist will conduct site evaluations and determine the overall qualifications of the applicant. Questions that relate to filling out the application can be directed to the Extension Viticulturist.

To maximize the success of this program, juice grape growers and other fruit growers are strongly encouraged to participate in this program. Each grower is required to implement and maintain vineyard management practices that will assure that the grapevines established under this program will be fully production for several years.

Some of the changes being considered by OGIC for the Vine Grant program are:

If you are considering applying for the Vine Grant program, be sure to contact Maurus Brown (330-263-3681 or brown.989@osu.edu) to set up a site visit. Any grower that is considering applying for a grant in 2000 should schedule a pre-approval site visit in the spring of 1999.

http://www2.oarde.ohio-state.edu/grape

Competition, Columbus. Contact OWPA at phone: 440-466-4417 and e-mail: winchell@2knownet.net for details.

ASEV at phone: 530-753-3142, fax: 530-753-3318, or e-mail: asevdavis@aol.com for detafls.

barrel manufacture, and winemaking. Contact Ellen Harkness at fax: 765-494-7953 for details.