Ohio Grape 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

14 October 2005

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Content:
   Crop Update
    Fungicide for Ice Wine
    Rain and Ripening
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Crop Update from OSU Research Vineyards
by Imed Dami and Greg Johns, OARDC

OARDC-Wooster:

This week we picked NY70 and NY 73. The fruit so far has been of a very good quality and reds have higher Brix than normal. This is primarily due to the higher than normal heat units accumulated. As of 13 October, GDD are at 3,016 in Wooster, compared to 2,727 last year;i.e. 290 more heat units. The normal GDD from April-Oct is about 2700 in Wooster. Our records show that this year may even top the 2002 which was an excellent vintage. The extra heat units are beneficial for the vines with more carbohydrate accumulation for both the fruit and the wood to harden-off. Let's hope for an Indian summer for the late reds like Cabernet Sauvignon.

Harvest Dates of varieties at OARDC-Wooster Vineyard

Seyval 9/14
Marsane 9/19
Pinot gris 9/19
Concord 9/27
Chardonnay 9/28
Vidal 10/8
Viognier 10/8
Traminette 10/8
NY 70 10/12
NY 73 10/12

AARS-Kingsville:

The Ashtabula Covered Bridge Festival has come and gone with only a fraction of the usual brilliant foliage revealing itself. The grapes, on the other hand, know it's fall and are ripening rapidly. Sugar levels continue to be 1-3 Brix above average and pH levels are holding in the low to mid 3.'s. On many varieties the acids have dropped by 0.05 to 0.1 over the past week. Some of the reds have taken a turn for the worse as a result of this weekends rains and we went in and harvested the Dornfelder and Kozma 55 due to fruit breakdown. The Petit Verdot and Kozma 525 was also harvested but they didn't show any sign of breakdown... both have very thick skin. Cabernet Franc has shown signs of berry shriveling but otherwise the fruit is in good condition. Riesling is showing some signs of fruit breakdown with little VA observed. Cab Sauvignon is holding tough along with Frontenac. NY62 berries are in perfect condition but this week are a little softer than last.

Harvest Dates of varieties at AARS-KingsvilleVineyard

Bianca 9/12
Pinot noir 9/15
Auxerrois 9/20
Pinot blanc 9/20
Pinot gris 9/21
Chardonnay 10/3
Concord 10/3
Fer Servadeau 10/4
NY 70 10/4
NY 73 10/4

Fungicide Option for Ice Wine Production
By Mike Ellis, Plant Pathologist, OARDC

For grapes being held in the vineyard for ice wine production it may be useful to make an application of Pristine fungicide about the time you would conduct normal harvest or a bit later. We are having abnormally high temperatures and ripe grapes hanging under these conditions may face problems with berry rots caused by fungi. With the premium price we can get for good ice wine, the cost of the spray should be more than justified.

Pristine is a very broad spectrum fungicide and should be helpful in protecting berries from attack by several fungi. These fungi should not be a problem after some good killing frosts and as winter starts to set in. Pristine can be applied at the rate of 6 to 10.5 ounces per acre. I would recommend the high rate.

Rain and Ripening
By Dr. Joseph Fiola, University of Maryland

Here are some things to consider when evaluating when to harvest the varieties that have weathered the storm:

After a significant rainfall, the water enters the berries in 24-36 hours.
Once in, the water that enters the fruit cause the following:
- Dilution of sugars – immediate drop in Brix
- Dilution of flavor components- secondary metabolites
- Causes or increases the risk of fruit splitting which leads to:
  - Decreased yields
  - Increased risk of botrytis and other late fruit rots
  - Increased problems with fruit flies and wasps, bees, etc.
Delayed harvest means extended risk of fruit predation form birds, deer, raccoons, turkeys, etc.
Varieties that were closest to being ripe face the greatest risk

What to consider/do:

Keep an eye on the short and long term weather reports.
If the weather is dry and warm (70+ days, 50+ nights) the grapes will slowly recover – Brix will increase and flavors will rebound. Whether they will make it all the way back depend on the weather conditions.
- It is already close to mid-October, so the probability of a significant spell of very desirable weather is not on our side.
Keeps an eye out for berry splitting and degeneration.
Keep an eye out for Botrytis and protect if necessary.
- Remember the risk of spraying our important fungicides on existing infections.
Monitor disease, bird and bee damage closely and make the harvest call based on those issues.
Also consider the productive capacity of your existing canopy.
- Many canopies are looking ragged and long term “hanging” of the fruit will not result in significant desirable ripening.
- If the leaves are still green and if the berries are sound, there can be some benefit to waiting.
If the forecast permits, it would be best to be patient monitor the forecast and disease, and allow the water to move out of the vine and the fruit to proceed forward again.
It is always preferable to harvest according to maturity but it seems the season is closing in on us. If the forecast is gloomy, the canopy weak, the disease and animal pressure high, you may have to cut your loses and get the fruit off.
Pray for an extended Indian summer!