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2022 Sentinel Vineyards
"state of the grape in the state" report 2
(09/02/22)
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TABLE OF CONTENTS
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Vineyard update
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Disease update
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Fruit chemistry update
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Novel Varieties project: basic fruit chemistry
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Vineyard Update
Contributor: Tremain Hatch, part-time Research Faculty
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As we start September, here is some context about the weather this season. Comparing heat accumulation over the previous two seasons and this season, the 2022 season is similar to 2021. Winchester is running slightly cooler than 2021, while in Crozet, 2022 is running slightly warmer than 2021.
In terms of rainfall: We have had a rainy summer, much more rain than most of the northeast. Rainfall in August has been variable around the state. The figure below shows cumulative rainfall looking backward over August at four locations around the state. The Northern Shenandoah valley, usually our driest area has been socked by a couple big rain events. Northern Virginia has seen less rainfall than other areas of the state. Even without excessive precipitation, humid conditions have driven downy mildew pressure.
Here in the Winchester area, we have been seeing adult spotted lanternflies for most of august, we noted that the honeydew excreted by the SLF adults has started accumulating on the canopy and fruit in August. The figures below are taken from Grape Pathology block of chardonnay – Mustang Maxx were applied once in August.
Take care and work carefully through harvest.
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Honeydew (sticky) on the leaf surface (blue arrow) and
fruit started appearing the week of 22 August in Winchester
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Disease update
Contributor: Mizuho Nita, PhD, Associate Professor & Extension Specialist for Grape Disease Management
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It looks like some portion of the state has been relatively dry in the past two weeks, but based on the NEWA’s DMCast, the risk of downy mildew has been high for most stations. Here’s a summary from the last week (showing the number of days with the risk of each disease: Ph = Phomopsis, PW = Powdery mildew, BR = Black rot, and DM = Downy mildew. Note: Floyd station has been out of order since early July. It will be up and running very soon! Please see more at my blog (https://ext.grapepathology.org).
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The high number of days with downy mildew risk is likely due to cooler nighttime temperatures, which drive the relative humidity high, and the downy mildew pathogen produces its spores under dark and wet conditions. Sometimes heavy dew is enough to spread spores (i.e., condensation water from the dew running down on the surface of leaves) and if they are producing spores, a short rain event can be enough to spread these spores. Thus, please make sure to protect your vines against downy mildew and other late-season diseases, such as ripe rot and sour rot. For more information, including the list of short-PHI spray materials, please visit my blog.
Hopefully, the dry spell continues. Happy harvest!
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Fruit Chemistry Update
Contributor: Beth Chang, PhD, Enology Extension Specialist
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Shortly after our last report, an industry partner sent an update that “things are moving”. Well said! Happily, many people saw a nice (often 2 °Brix or more) bump in their sugars in mid-August, and while things slowed down slightly in the past week due to the cooler weather, accumulation continues. These observations can be seen in the Chardonnay data presented below in Figure 1. Several partners indicated that they have harvested Chardonnay this week, or have plans to do so shortly. Figure 2 shows a comparison of pH to total soluble solids (TSS; measured in °Brix). pHs are currently between 3.1 – 3.35, with sugars between 16 – 20 °Brix.
Looking back at last year’s data, we have almost caught up in sugar accumulation, while pHs are lower than last year. Fingers crossed that this trend continues in other varieties. Dovetailing with the mildly lower pHs, TAs are tracking 1-2 g/L higher than 2021. TAs from across the Commonwealth are around 8 g/L, but of course there is a lot of spread (Fig. 3). Figure 4 shows berry weight versus TSS; we see a range from ~1.35-1.7 g/berry for fruit at 17-19 °Brix. There is also a great example of sugar loading (calculating sugar per berry) as a useful tool for seasons such as this one, when rainfall can cause temporary swelling. Based on the fit line for the “Central 7” Chardonnay, it appears that berry size decreased as TSS increased. However, standardizing for berry volume tells us that sugar is indeed continuing to accumulate.
Hope that everyone continues to do well we get deeper into the season. There should be a more detailed Cabernet Franc update in our next report as people begin monitoring more closely.
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Novel Varieties Trial Summary
Contributor: Dana Acimovic, Viticulture Research Associate
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Varieties Trial objective is the evaluation and data collection on phenology, vegetative characteristics, reproductive disorders, yield components and vine size, primary fruit chemistry, dormant bud cold hardiness, and noteworthy nutrient deficiencies, disease or pest problems. For that purpose, we recorded the dates when each variety reached veraison or more precisely when 50% of the berries were in stage EL-35. Itasca, as currently the only hybrid variety, entered veraison the earliest, on July 12, and was followed by Fleurtai, and Garanoir. Soreli, Gamaret, and Petra reached veraison during the last week of July, or at the same time as Chardonnay. Teraldego, an old Italian variety, and Verdejo, from the Rueda region of Spain entered veraison in the first week of August. They are the part of the varieties trial as the vines that do not possess tolerance or obvious resistance to diseases. The last to reached veraison, were San Marco and Seperavi, which berries turned red at the same time as Cabernet Franc’s.
Berry sampling for basic fruit chemistry was done during the second week of August and data are presented in a table below. As expected based on ripening time, Itasca showed the highest Brix level of 20.1 %. The lowest brix of 9.9 % was recorded in Verdejo, a white that reached veraison the latest. Among tested varieties, juice acidity was in range from 2.72 to 3.31. The least amount of titratable acidity was detected in Fleurtai, only 6.7 g/L, while the highest TA were present in the late ripening reds - San Marco and Saperavi.
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Virginia Cooperative Extension programs and employment are open to all, regardless of age, color, disability, gender, gender identity, gender expression, national origin, political affiliation, race, religion, sexual orientation, genetic information, veteran status, or any other basis protected by law. An equal opportunity/affirmative action employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
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