Ohio Grape-Wine Electronic Newsletter

Editor: Imed Dami, PhD
Assistant Professor, Viticulture Specialist
Department of Horticulture and Crop Science
Ohio Agricultural Research and Development Center
1680 Madison Avenue
Wooster, OH 44691-4096
Phone: (330)-263-3882
Fax: (330)-263-3887
E-mail: dami.1@osu.edu
 www.oardc.ohio-state.edu/grapeweb/


 
 
 
25 September 2006
 
 
===========================================================
 Content:
 
2007 Ohio Grape-Wine Short Course
GDD and Fruit Maturity
Management of MALB
Fruit Rot and Wine Quality
Grapes Wanted
Upcoming Events
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2007 Short Course -- Mark Your Calendar!

The 2007 Ohio Grape-Wine Short Course will be held on 12-13 February at the Shisler Conference Center at OARDC in Wooster, OH. Please mark your calendar. More information later.


GDD and Fruit Maturity 
by Imed Dami, HCS-OARDC

Grape maturity can be monitored on the basis of “Growing Degree Days” (GDD) or “Heat Units” and not by calendar dates. Grape varieties usually require a certain number of GDD to reach maturity regardless of the number of days taken to accumulate them. There are several ways of calculating GDD, the most common for grapes is to subtract 50 degrees F from the mean daily temperature. Daily GDD are then added or accumulated from 1 April through 31 October to correspond roughly to the growing season of grapes.
 
GDD Formula = (Maximum Temperature + Minimum Temperature)/2 -50 F
 
For example, if Max temp=85F and Min Temp=55F then GDD on that day equals (85+55)/2-50 = 20.
 
The yearly accumulation of GDD in Ohio ranges from less than 2500 GDD in northeastern counties to more than 3000 GDD in southern counties along the Ohio River. Based on GDD, this season is definitely cooler than 2005 which was unusually warm (200-300 more GDD than normal throughout the state). An example of GDD data from the AARS is listed below and attached (courtesy of Greg Johns, AARS Manager) to demonstrate GDD variation from month to month and year to year. In 2006, even though it seems much cooler than normal, in reality spring has been warmer, June cooler, and July and August warmer than normal. However, September has been cool and currently as of September 24th, only 294 GDD has been accumulated (lower than the normal 384 GDD). We have 6 more days to go though.
 
This may explain delays of fruit ripening in some varieties (especially late varieties) as indicated by grape growers and observed in our research vineyards. However we can’t use last year dates of harvest as references. For example in 2005, we picked Pinot noir at AARS on 15 September, which corresponded to 2,482 GDD. This year, by 15 September only 2,327 GDD have been accumulated or 155 GDD less than in 2005. We have to wait until 2,400+ GDD are accumulated to reach maturity and optimum fruit composition which means harvest of Pint noir in 2006 will be about two weeks later than in 2005.   
 
Another explanation of delay in fruit maturity is the unsynchronized fruit ripening that we have experienced this year due to the spring frost damage in April-May. Fruit does not ripen uniformly when it does not originate from the same buds. Primary buds break first thus produce clusters first. Secondary buds break later and thus produce clusters later. Ripening of clusters from secondary buds lags behind and may not catch up by harvest depending on crop load.  That’s why crop estimation and cluster thinning are important to regulate crop and minimize uneven ripening.
 
What’s the bottom line? When conducting fruit sampling, pick berries from both kinds of clusters (usually primary clusters are larger than secondary clusters) to have representative sample. Be patient on the harvest date since cluster ripening is not uniform (unless the fruit is falling apart because of rot). Fruit picked at harvest is almost always less ripe than your sample. This difference will be even more pronounced this year due to variation of cluster ripening within vines. Let’s hope for a warm October and plenty of GDD to ripen our late and red varieties. To check GDD in your area, visit this website http://phenology.osu.edu/ or http://www.oardc.ohio-state.edu/gdd/. Have a great harvest


Management of MALB
By: Imed Dami, Roger Williams, and Dan Fickle

It’s the time of year again that the Multicolored Asian lady beetle (MALB) whose presence is that of a beneficial predator throughout the growing season becomes an unwelcome pest at harvest.  For those not familiar with MALB, here is a background on its biology, life cycle, and identification:
Adults & larvae are generalist predators that feed on aphids, scale insects, mites, and other insects (All of the above pests damage agricultural crops, home, garden, and landscape plantings)
·         In summer they find food, find a mate, and reproduce.  There may be several generations per year with a larger proportion of later generations predisposed to over wintering.
·         Aggregation behavior (searching for overwintering sites and fruit crops) is triggered by the start of shorter days and cooler temps - when temperatures drop quickly followed by a sunny day.
·         Adult beetles have been found to vector fungal diseases, and therefore their aggregating nature may be favorable to the dissemination of bunch rot and other diseases from one grapevine to another.
·         MALB does not cause direct fruit injury but instead will infest fruit previously damaged by other insects, pathogens, rots, birds, and wasps.
·         When disturbed or crushed, MALB respond by "reflex bleeding" which forces hemolymph out of their joints.  This alkaloid is highly unpleasant to taste and smell and can irreversibly taint the aroma and flavor of the resulting wine.
·         Remember that only a handful (10 to 12 beetles per lug) can be a sufficient number for concern in white grape varieties.  If these beetles are present at crush they can taint the juice which in turn may be detectable later in the wine. 
·         There is a major amount of color variation within the MALB
o        Red color due to high quality of food eaten as larva (i.e., lots of tasty aphids)
o        Yellowish color due to fewer aphids consumed but more pollen as a larva
o        More spots, lower temperature and a longer duration of pupa stage
o        Fewer spots, higher temperature and a shorter duration of pupa stage
·         Many beetles have a straw-colored pronotum (top covering of middle body part) with markings that fuse into a regular- to irregularly-shaped "M" if viewed from the front, or "W" if viewed from behind.
Scouting and Management:
·         Growers concerned about ladybeetles should be scouting fields regularly for the first signs of the beetle. Monitoring should begin 14 days prior to expected harvest for each cultivar
·         Control fruit rots, as these will attract the beetles.
·         Mechanical or hand harvesting during the daytime may sufficiently shake the vines to cause the beetles to leave the grape clusters ahead of the harvester.
·         Night harvesting may not create this effect as the beetle burrows deep into the cluster and becomes much less active.
·         Remember these are lady beetles, which are typically considered VERY DESIRABLE, so labeled control is limited.
·         Ladybeetles are efficient predators of pest insects for the majority of the growing season, and most chemical controls for this introduced beetle will also kill native predators thereby allowing other insects and mites to become a problem.
·         Since the crop typically becomes infested just prior to harvest, growers’ options are restricted by the need for materials with a very short PHI (pre-harvest interval).
·         While these insecticides do a good job of knocking down the population, dead beetles often times can remain in or on the cluster.  If harvested along with the fruit, the dead beetles can still taint the wine for at least 2 days.
·         Products which have shown repellancy and efficacy against this insect are, azadirachtin (Azatrol, Aza-Direct), and imidacloprid (Provado) both of which have a zero day pre-harvest interval (PHI). 
·         Two newly labeled products this season have demonstrated good efficacy against MALB for up to 4 days post treatment and both have minimal harvest restrictions. Venom may be applied up to 1 day prior to harvest and Baythroid 3 days prior to harvest. 
 
Venom (dinotefuran), (Valent USA): This is a third generation neonicotinoid which provides excellent control of sucking insects, such as leafhoppers, aphids and mealybugs. It has demonstrated good efficacy for up to 4 days post treatment against the Multicolored Asian lady beetle (MALB).   The harvest restriction interval for foliar application is only 1 day so we believe it will be a valuable tool in controlling late season MALB infestations.  Take note that this product is listed on page 49 of the 2006 Midwest Commercial Small Fruit and Grape Spray Guide as having a 52 day harvest restriction on grapes. This is a typo and should read 1 day when applied as a foliar application and 28 days if applied as a soil drench.  
 
Baythroid (cyfluthrin), (Bayer Crop Science): This is a new pyrethroid similar to Capture and Danitol.  It’s labeled for control of flea beetle, grape berry moth, leafhoppers, cutworms, grape leaf skeletonizer, and glassy winged sharpshooter.  We tested this product over a decade ago and found it to also provide good control of Japanese beetle and foliar phylloxera.  Additional studies in the laboratory this winter have demonstrated good efficacy against the MALB.  One very important aspect of this new product is that it has only a 3-day harvest restriction.  This is the first labeled pyrethroid with a short harvest interval making it a good candidate for late season control of MALB and grape berry moth.   This product is not listed in your 2006 spray guide so look to the product label for recommended rates.

More Information:
Here are some good web sites to check for pictures and fact sheets for more detailed information:
The Ohio State University website: http://ipm.osu.edu/lady/lady.htm
Iowa State Insect Notes: http://www.ent.iastate.edu/ipm/iiin/ladybeetles.html
Michigan State University web site: http://www.ipm.msu.edu/beetleFruit.htm
 

Effects of Fruit Rots on Wine Quality 
By Dr. Bruce W. Zoecklein, Enologist at Virginia Tech (Reprinted by permission)

[Editor’s note: Due to excessive rain we have had in July-Sept, fruit rot is expected to be a problem this year. In this season, there may be a need for fruit inspection and fruit culling at the winery.  The article below graciously contributed by Dr. Zoecklein, Extension Enologist in Virginia, describes the effect of fruit rot on juice quality.  It also describes the cause of wine haziness, which winemakers may experience…well not winemakers, rather the wines!].
 
Both Botrytis cinerea and sour rot have significant influence on wine chemistry (Table 1). The largest quantitative changes occurring in the fruit as a result of Botrytis growth are those of sugars and organic acids.
 
Table 1. Comparison between Virginia White Riesling Musts (attached)
 
 
 
Botrytis and sour rot use ammonia nitrogen, reducing the levels available for yeast metabolism. Additionally, thiamine (vitamin B1) and pyridoxine (vitamin B6) are depleted. This is a primary reason why I have suggested that wines produced from Botrytis and/or sour rot infected grapes generally require supplementation with nitrogen and vitamins to help avoid stuck fermentations and possible H2S/mercaptan formation. Like other fungi, Botrytis cinerea produces laccase, which catalyzes phenolic oxidation. This coupled with loss of varietal aroma is a major problem with fruit rots. The main nonflavonoid phenolic compounds of grapes are caffeic and p-coumaric acids, both free and esterified with tartaric acid. These are transformed to quinines by laccase, with resultant polymerization responsible for browning of the fruit. Excessive browning and the concentration of laccase can generally be limited by whole cluster pressing, the elimination of the first 10-15 gallons/ton and the use of PVPP. Laccase is resistant to sulfur dioxide, cannot easily be removed with bentonite, and is active in the presence of alcohol. Therefore, the reduction pre-fermentation is important. Elevated levels of acetic and lactic acid are frequently seen in wines made from Botrytis-infected fruit. These spoilage acids arise from growth of yeast and bacteria associated with the mold. Aspergillus, Botrytis, and Penicillium sp. oxidize glucose to produce gluconic acid. Since gluconic acid is not utilized by yeast or bacteria it may be used as an indicator of fruit deterioration. Gluconic acid levels in “clean” fruit and in wines made from clean fruit are near 0.5 g/L, whereas in wines produced from fruit infected with B. cinerea levels range from 1 to 5 g/L. In the case of sour rot or vulgar rot, where bacterial growth occurs along with the mold growth, levels may also reach 5 g/L.
 
 

Polysaccharide Instability

One of the greatest impacts of Botrytis growth and sour rot is the formation of polysaccharides that create clarification problems. Pectins are hydrolyzed by mold-produced polygalacturonase, with the formation of beta-1,2- and 1,6-glucans. In wine, ethyl alcohol causes the glucan chains to aggregate, thus inhibiting clarification and filtration. Commercially, several glucanases are available to minimize these clarification problems. Polysaccharides can form protective colloids in juices and wines inhibiting clarification, fining, and filtration. In grape juices and wines polysaccharides may be in the form of pectins and/or glucans, each forming gelatinous aggregates in an alcohol solution. Several Virginia producers have reported polysaccharide instabilities this season. The following, adapted from Zoecklein et al. (1995), are two simple lab procedures for determining pectin and glucan instability.
 
Pectin Instability
Pectins are structural components of plant cell walls. If pectins are present, the addition of pectolytic enzymes to a laboratory sample and subsequent pectin precipitation test is recommended.
 
Procedure: To a 25-mL aliquot of the wine containing unidentified haze, add 50 mL of a 95% ethanol: 1% HCl or alternatively, isopropanol: 1% HCl reagent.
 
Interpretation: Formation of gel after several minutes is indicative of pectin.
 
Glucan Instability
Dubourdieu et al. (1981) developed two precipitation tests for glucans. The first procedure given is for the presence of glucans in concentrations greater than 15 mg/L, the second for levels as low as 3 mg/L. Even at low concentrations, glucans can cause filtration problems. A positive test for the presence of glucans should be followed by a laboratory fining trial using glucanases and retesting.
Procedure for Glucans > 15 mg/L: Add 5 mL of 96% ethanol (vol/vol) acidulated with 1% HCl to a tube containing 10 mL of juice or wine.
 
Interpretation: The formation of a white filament is indicative of the presence of glucans at levels greater than 15 mg/L. Because much lower levels can cause problems, an additional test that will detect glucans at concentrations above 3 mg/L may be warranted.
 
Procedure for Glucans > 3 mg/L:
1.      5 mL of wine is mixed with 5 mL of 96% ethanol (vol/vol) acidulated with 1% HCl.
2.      After 30 minutes at room temperature the mixture is centrifuged at 3,000 g for 20 min.
3.      The supernatant is carefully removed and the precipitate redissolved in 1 mL water. The precipitate is then mixed with 0.5 mL acidulated ethanol.
 
Interpretation: The formation of filaments is indicative of glucans.
 

 Grapes Wanted

If you have a vineyard and/or winery and you have Traminette grapes (1 ton) to sell, please contact Bill Skvarla, Harmony Hill Vineyards at 513-315-8786 or Harmonyhillfarm@aol.com. Thanks.


 Upcoming Events:
 
October 6-7, U.S. Highbush Blueberry Council Fall Meeting.  Regency, Bar Harbor, Maine , Regency, Bar Harbor, Maine. For more information  (207) 288-9723.
 
November 9-11, Southeast Strawberry Expo, Sunset Beach, NC (near Wilmington). Farm tour, intensive workshops on Strawberry Plasticulture ABCs and High Tunnel Production, tradeshow, many educational sessions on production and marketing. For more information, contact the NC Strawberry Association, 919-542-3687 or ncstrawberry@mindspring.com
 
December 5-7, Great Lakes Fruit, Vegetable and Farm Market EXPO. DeVos Place, Grand Rapids, Mich., www.glexpo.com..
 
January 7-9, 2007, Wisconsin Fresh Fruit and Vegetable Conference, Olympia Resort and Conference Center, Oconomowoc, www.wisconsinfreshproduce.org
 
Jan. 8-9, 2007, Kentucky Fruit and Vegetable Conference and Trade Show, Holiday Inn North, Lexington, KY. Contact John Strang 859-257-5685; e-mail jstrang@uky.edu
 
January 25-28, 2007, Southern Sustainable Agriculture Conference. The Galt House Hotel and Suites, Louisville, Ky. For more information (678) 494-0696
 
January 30-February1, 2007, Mid-Atlantic Fruit & Vegetable Convention. Hershey Lodge &. Convention Center, Hershey PA
 
February 9-12, 2007, North American Strawberry Growers Association Strawberry Symposium. Ventura, California.  More program details (abstract deadlines, keynote speakers, etc.) and opportunities for industry, organization and agency sponsorship will be announced on the NASGA website http://www.nasga.org/.
 
February 12-13, 2007, Ohio Grape-Wine Short Course. Shisler Center OARDC, Wooster, OH. 

February 14-15, 2007, Empire State Fruit and Vegetable Expo  Syracuse, N.Y. For more information  www.nysaes.cornell.edu/hort/expo.
 
February 16-17, 2007,  North American Farmers' Direct Marketing Conference and Trade Show.  Hyatt Regency Hotel, Calgary, Alberta, Canada. For more information www.nafdma.com..