Winemakers, Watch Out for Candida Mycoderma, p.1
Oak From Forest to Glass, p.2
Winery Sanitation, p.3
Bird Control for Vineyards, p.5
Grape Insect Pests, p.8
Please visit our web site at: http://www.oardc.ohio-state.edu/grape

What is Candida mycoderma? Candida is the primary Genus of yeast that causes "Film Yeast" in our wines. Mycoderma is a general term for a mixed population of several different yeast, molds, and bacteria that contribute to film yeast. A term otherwise known as "wine flower" describes this aerobic yeast which gives a chalky fragile white film on the surface of wines. These species of Candida can utilize ethanol as a source of carbon and form a film or pellicle on the wine surface. They are strongly oxidative and lead to a decrease in ethanol content along with an increase in acetaldehyde concentration. This acetaldehyde content contributes to an objectionable oxidized flavor. Acetaldehyde is also an intermediate component of acetic acid formation by acetic acid bacteria.

It is essential to prevent film yeast from forming in your wines. Since Candida needs aerobic conditions to live, it is crucial to keep oxygen from attacking your wine. This is done by keeping your head space to a minimum. Transfer lines, pumps, and receiving tanks may be purged with an inert gas such as nitrogen before use. Also, by keeping your tanks and barrels filled to the top will prevent oxygen from attacking your wine.

A second important step in preventing film yeast from occurring is with the addition of sulfur dioxide. Special attention should be given to your concentrations of "free" sulfur dioxide. Under most conditions, maintaining 25 to 40 ppm of "free" sulfur dioxide will protect wines in storage from film yeast, bacteria and other microorganisms. By doing this you will be well on your way of producing a sound quality wine.

Cellar temperature is a third factor in helping to prevent film yeast formation. Temperatures above 12°C (54°F) are more favorable for film yeast formation. Therefore, keeping your wine storage temperatures below 12°C will be an important preventive measure. The cooler that you can store your wines, the more beneficial it will be toward producing a stable wine.

B.W. Zoeklein, K.C. Fugelsang, B.H. Gump, F.S. Nury, 1995.Wine Analysis and Production. New York. Chapman & Hall, 14:220-221.

M.A. Amerine, M.A. Joslyn, 1970. Table Wines. Univ. of Cal. Press, Berkley.

A symposium discussing the use of oak in wine is scheduled July 14-16, 1999 in St. Louis. This event will precede the annual meeting of the American Society for Enology and Viticulture-ES, which begins July 17. The symposium will bring together suppliers, winemakers and research personnel to discuss the practical applications of oak in winemaking. It begins July 14 with a tour (for the first 200 registrants) sponsored by World Cooperage of their forest and production facilities. The program continues July 15-16 with discussion of the following topics:

- Chemistry and composition of oak wood. Characteristics of various oaks (American, French, etc.), and their sensory significance.

- Wood transformation during natural seasoning of oak wood and its influence on wine composition and sensory qualities. Influence of leaching, chemical oxidation, hydrolysis, and chemical transformation. Microbial activity and wood maturation. Optimal conditions for wood maturation. Influence of flora on chemical composition of oak wood.

- Effect of heating and toast levels on composition and organoleptic characteristics of wine.

- Extraction of oak wood constituents during wine maturation and their contributions to wine aroma and flavor.

- Barrel fermentation and maturation of red wine.

- Barrel fermentation and maturation of white wine.

- Sur lie and wine flavor.

- Principles and practices of sur lie aging of white wine with emphasis on: Influence of yeast fermentation on volatile oak extractives, and influence of lees contact time and stirring regime on wine quality.

- Modern methods of cooperage production.

- Microbial contamination and rehabilitation of barrels.

- Barrel alternatives in wine production.

- Barrel management in the cellar:

Buying, treating, and conditioning of new and used barrels.

Handling and storage of full and empty barrels.

Barrel defects, repair, and maintenance.

Barrel cleaning and sanitation; using ozone as a sanitizer.

Ullage, topping, and racking.

- Conducting oak trials in the winery.

Winery Sanitation by Roland Riesen

Proper cleaning and sanitation is more important than ever before in maintaining wine quality. Uncontrolled growth of microorganisms can eventually lead to product deterioration and spoilage. The following is a review of winery sanitation and cleaners adapted from Wine Analysis and Production (Zoecklein et al., 1995). Reprint from "Vineyard & Winery Information Series" (May-June, 1995), with permission of Bruce W. Zoecklein, Department of Food Science and Technlogy, VPI & SU - 0418, Blacksburg, VA.

Strong alkalies, including NaOH (caustic soda) or KOH (caustic potash), and sodium carbonate (Na₂CO₃) are the most commonly used detergents. Both NaOH and KOH have excellent detergent properties and are strongly antimicrobial. Unfortunately, they may also be corrosive, even to stainless steel, if recommended application levels are exceeded. Handling strong alkalies requires use of protective gloves and eyewear.

Sodium ortho- and meta-silicates (Na₂SiO₃) are less caustic than NaOH and have better detergency properties. They are also less corrosive. Where the organic load is not heavy, mild alkalies such as sodium carbonate (soda ash), or trisodium phosphate (TSP) find application. Sodium carbonate is an inexpensive, frequently used detergent. Unfortunately, in hard water Na₂CO₃ contributes to precipitate formation.

Acids are used in specialized detergent formulations to reduce mineral deposits and soften water. Maximum effectiveness occurs at pH 2.5. At low pH's, acid solutions are very corrosive toward stainless steel (and other metals). Phosphoric acid is preferred because of its relatively low corrosiveness and compatibility with nonionic wetting agents.

Once deposits are removed and the surface is visibly clean, it can be sanitized. Two general categories of chemical sanitizing agents are currently in use: the halogens, including chlorine and iodine, and Quaternary Ammonium Compounds (QUATS). Additionally, some winemakers attempt to use sulfur dioxide as a sanitizer agent.

Chlorine in its active form, hypochlorous acid (HOCl), is a powerful oxidant and antimicrobial agent. Molecular hypochlorous acid is present in highest concentration at near pH 4, decreasing rapidly with increased pH. At pH greater than 5, hypochlorite (OCl^-) increases whereas at pH less than 4, chlorine gas (Cl₂) increases. Neither chlorine gas nor hypochorite have been shown to be active against microorganisms; however, both are very corrosive. Formation of chlorine gas is also a safety issue. Because there are still substantial amounts of HOCl present at pH greater than 6.5, sanitizing operations are typically carried out in the pH range 6.5-7.0.

Chlorine is an oxidant whose activity will prematurely degrade if organic residues (reflecting inadequate cleaning) are present. Therefore, proper cleaning prior to sanitation is essential. Reaction time for chlorine is temperature dependent. Up to 52^oC (125^oF), the reaction rate (and corrosive properties) doubles for each 10^oC (18^o) increase in temperature.

Sanitizing surfaces requires active chlorine concentrations of 100-200 mg/L. Although chlorine is compatible with stainless steel surfaces at recommended levels, severe oxidation (pitting) may result from use of larger amounts. Upon completion of the operation thorough rinsing is required to remove remaining sanitizer.

Formulations including iodine and nonionic wetting agents are called iodophors. Iodine (I₂) is the active principal and thus iodophors are most effective in the pH range 4 to 5 where the concentration of I₂ is maximum. To ensure activity, formulations typically include phosphoric acid. The sanitizer has the advantage of low use levels. A concentration of 25 mg/L of iodophore is equivalent to 200 mg/L chorine. Iodophores are frequently used for bottling sanitation, followed by a cold-water rinse.

Compared with OHCl (hypochlorous acid), iodophores are not as readily degraded by organics (dirt) and are nonirritating at recommended use levels. I₂ becomes volatile at temperatures greater than 49^oC (120^oF). Formulations containing iodophores may stain polyvinylchoride and other surfaces.

In some cases, winemakers use SO₂ as a sanitizing agent. The effectiveness of SO₂ against microbes is pH dependent. Depending on the physical properties of the surface and level of organic debris, circulating a solution of 10 g/hL SO₂ (or 20 g/hL potassium metabisulfite) and 300 g/hL citric acid at 60^oC (140^oF) may be effective.

Hot (82^oC/180^oF) water or steam is an ideal sterilant. It has penetrative properties, works against all wine/juice microorganisms, is noncorrosive, leaves no residues and is relatively inexpensive. Where hot water is employed to sanitize bottling lines, it is recommended that temperatures greater than 82^oC for more than 20 minutes be used. The temperature should be monitored at the farthest point from the stream source (i.e., the end of the line, fill spouts, etc.). When steam is used to sterilize tanks, the recommendation is to continue until condensate from valves reaches temperatures greater than 82^oC for 20 minutes. Dismantling valves, racking arms, etc., is desirable for cleaning and sanitizing.

Following sanitation, all surfaces must be thoroughly rinsed to flush residual sanitizer and solubilized debris. Tank/hose sanitation is typically followed by citric acid rinse to neutralize residual alkali. The final rinse water should be tested for residual oxidants. This may be done in the laboratory or cellar by use of "kits" designed for this purpose. The presence of residual sanitizer can often be noted by smelling the rinse water. It is essential that all residual sanitizer be removed prior to wine contact. A very small concentration of sanitizer will cause wine oxidation!

The most frequently encountered method for evaluating cleaning operations is sensory. Visually, does the surface appear clean; by touch, does it feel clean; and equally important, does it smell clean? A slippery surface or the presence of "off" odors is indicative of inadequate cleaning or rinsing of detergent. Although a quick sensory review may be adequate for fermenters and storage tanks, other areas (e.g., bottling lines) require further examination. In these cases, follow-up microbiological examination should be conducted. A variety of tests are used and involve sampling a defined area with sterile cotton swabs, agar surfaces, or special adhesive strips.

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Crop damage in wine grape vineyards due to bird depredation appears to be more pronounced than in years past. This may be due in part to the increasing acreage of highly palatable wine grape varieties being grown. Several Ohio wine grape growers have found that birds are attracted to the early ripening varieties such as Marechal Foch, Leon Millot, and Baco noir. There is commonly an increase in bird activity in vineyards as the berries near veraison. This is a critical time to persuade the birds to move elsewhere or try to prevent them from reaching the mature berries. Most growers will sustain the greatest damage in early maturing varieties, which is certainly characteristic of all fruit crops.

Birds that are commonly observed in North American vineyards are European starling, American robin, Northern mockingbird, Northern oriole and Common grackle. Other birds such as House finch, Cardinal, Cedar waxwing, Gray catbirds and American goldfinch have also been observed in vineyards at various times. Migrating or local flocks of birds will begin testing grape berries at veraison.

Several different types of control measures have been implemented in vineyards to deter birds from feeding (6).

Bird Netting. Growers have often tried to exclude birds from the grape canopy by draping bird netting over each individual trellis row. Netting is usually rolled out between the rows and pulled over each trellis and fastened together to prevent netting from blowing off. This provides a good barrier to feeding birds. Some growers have devised mechanical rollers to layout and take up bird netting. Netting must be in place by early veraison to assure that no fruit is damaged or lost.

Visual Repellents. Some of the most frequently used devices include scare-eye balloons, mylar tape, tin pans, streamers and other shiny and fluttering objects. The effectiveness of these visual deterrents has been limited. Birds are very capable of adjusting to new objects in a relatively short period of time. This type of deterrent should only be used in a limited time frame and more appropriately should be included in an integrated bird management system.

Bird of Prey. Some growers have tried to set up nesting polls to encourage falcons and hawks to nest in vineyards. When large avian preditors are active in the vineyard, fruit eating birds will tend to stay away from the area.

Sound Repellents. Propane cannons have been randomly placed in vineyards and set to go off at designated time intervals. Alarm systems that imitate bird distress sounds of can also be located in the vineyard and will sound on a preset time schedule. Some of the more sophisticated systems can produce distress calls from different bird species, alternating the sound and length of time of each. The loud or distress noise will generally induce a panic in the birds and they take flight to avoid a perceived danger. As with the sight deterrents, birds often become acclimated in time to new sounds introduced into the vineyard. Once the birds become aware that the sound does not immediately signal an impending danger, they are less likely to take flight. These devices should be used selectively with other control measures and moved around the vineyard to reduce bird familiarity. One point of concern is that the sounds produced to deter birds often are quite annoying to neighbors living near the vineyard, so consideration should be give to the frequency and timing of when these devices are set to go off. In some cases, growers have resorted to shooting a shotgun over the vineyard to scare birds off. This can be time consuming and costly in terms of shells. Pyrotechnic pistols have also been used to create noise to scare birds from vineyards. As with the shotgun approach, the grower will have to continue scouting the vineyard for birds roosting on trellises.

Chemical Repellents. This approach to bird control is fundamentally different from other deterrents in that growers must apply some type of chemical compound to grapes. Birds find fruit treated with a biochemical agent to be distasteful. Different chemicals have been tested as repellents to reduce bird depredation in fruit crops.

Methiocarb (carbamate) use on fruit crops was terminated in the late 1980’s (4) and it does not appear likely that this compound will be registered for use on fruit crops in the near future.

Methyl anthranilate, a naturally occurring compound in ‘Concord’ grapes, was found to reduce bird-feeding (3), but a noticeable "foxy flavor" appeared in wine produced from Vinifera and French hybrid grapes treated with this chemical.

Sucrose (disaccharide) has been used to reduce bird depredation in fruit crops. Research conducted at Cornell University showed that birds were less likely to consume blueberries sprayed with sucrose (8). Red-winged blackbirds, American robins, and European starlings have reacted negatively to solutions of sucrose in feeding trials (1,2,7). No research to date has been conducted to determine what affect sucrose would have on bird feeding in grapes or the quality of wine produced from grapes treated with sucrose. If sucrose could significantly reduce bird depredation and not negatively impact production or wine quality, then growers would certainly have a much more environmentally friendly chemical to apply for bird control.

Anthraquinone (AQ) is a bird repellent compound that may have potential for controlling bird feeding in grapes. There have been no reports of research on fruit crops treated with AQ. Thus far, scientists at the USDA, National Wildlife Research Center at Sandusky, OH have studied the use of AQ repellent applied to turf and grain to determine the feeding response of Canada geese, Brown-headed cowbirds and Red-winged blackbirds (5). There was some reduction in feeding by birds, however, it was noted that the potency of AQ was reduced at around 6-7 days after application. This would indicate that additional applications of AQ are required at regular intervals to provide adequate protection. Anthraquinone is not labeled for commercial use at this time (5), but will require a period of testing to determine if AQ could be a safe compound for use on grapes.

1. Brugger, K.E. 1992. Repellency of sucrose to captive American robins. J. Wildl. Mang. 58:794-799.

2. Brugger, K.E., P. Nole, C.I. Phillips. 1993. Sucrose repellency to European starlings: Will high-sucrose cultivars deter bird damage to fruit? Ecolog. Appl. 3:256-261.

3. Curtis, P.D., I.A. Merwin, M.P. Pritts, and D.V. Peterson. 1994. Chemical repellents and plastic netting for reducing bird damage to sweet cherries, blueberries, and grapes. HortScience 29(10):1151-1155.

4. Dolbeer, R.A., M.L. Avery, and M.E. Tobin. 1994. Assessment of field hazards to birds from methiocarb applications to fruit crops. Pestic. Sci. 40:147-161.

5. Dolbeer, R.A., T.W. Seamans, B.F. Blackwell, and J.L. Belant. Anthraquinone formulation (Flight Control ä ) shows promise as avian feeding repellent. J. Wildl. Mgt. 62(4):1558-1564.

6. Fraser, H.W., K.H. Fisher, and I Frensch. 1998. Bird control on grape and tender fruit farms, factsheet AGDEX 685.730, Ministry of Agri. Food and Rural Affairs, Ontario.

7. Rogers, J.G. (Jr.). 1974. Responses of caged Red-winged blackbirds to two types of repellents. J. Wildl. Mang. 38:418-423.

8. Socci, A.N., M.P. Pritts, and M.J. Kelly. 1997. Potential use of sucrose as a feeding deterrent for frugivorous birds. HortTechnology 7:250-253.

9. Tobin, M.E., R.A. Dolbeer, C.M. Webster, and T.W. Seamans. 1991. Cultivar differences in bird damage to cherries. Wildl. Soc. Bul. 19:190-194.

Contact OWPA (440-466-4417) to make reservations.

10:00 Positioning Vintage Ohio as a Marketing Tool – D. Winchell

10:10 Sponsorship Development – M.B. Lee

11:25 Working with the Media – S. Kish Jordan

11:40 Working the Crowd – C. Fassnacht

11:55 Discussion

12:05 Outside Speaker – Success Tips and Do’s and Don’ts

12:35 Outside Speaker – Success Tips and Do’s and Don’ts

1:05 Lunch on your own

2:00 Techniques of Alcohol Management Certification

4:00 Adjourn

Disclaimer Clause

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.