9 Viticulture Information News: No. 01 — Jan. 23, 2023 / Grape and Wine Institute / University of Missouri

Grape and Wine Institute

University of

Vinews

No. 01 — Jan. 23, 2023

Contents:

Show Me Grape and Wine Conference and Symposium

Show Me Grape and Wine Conference and Symposium:
March 1-2, 2023

Beginner Grape School:
March 3, 2023

Registration is open for both these events. Registration deadline is Feb. 21.

Book your hotel by Feb. 5 for the discounted rate. See more information on our conference page

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Assess Bud Survival Prior to Pruning

Figure labeled for average air tempterature by days of the month, and three lines to indicate the data for each October, November and December months. Dec. 21, the line significantly drops to an air temperature below freezing; it goes back up around the 27th.
Figure 1. Average air temperatures for October through December 2022. Notice the quick drop in temperature and extended period below 0 degrees F outlined in red.

An extended cold-climatic event occurred in late December 2022. Average air temperatures were below 0 degrees F for 24 hours starting on Dec. 22 (Figure 1). This event will have an impact on the 2023 crop depending on how you manage your grapevines going forward. Anytime when air temperatures fall below 0 degrees F during the dormant season the count-buds of grapevines should be evaluated prior to dormant pruning (Figure 2). This information can then be used to modify the number of count-buds to leave per grapevine. Understandably, some vineyards may have been pruned prior to this cold period. These vineyards should also be evaluated for bud health. An example of a cultivar that is often pruned early is Norton. Bud damage to early pruned grape cultivars provides you information on crop loss. As an example, 50% primary count-bud death of Norton provides an indication of 50% yield loss since Norton seldom fruits from secondary buds. This information can then be used to potentially source grapes from other local growers.

cross-section photos of a bud labeled A: healthy vignoles bud is shades of light green; B: bud damage in the vignole looks dry and brown
Figure 2. Healthy Vignoles bud (A) and Primary bud damage in a Vignoles bud (B). Evaluated on January 20, 2023. Photo credit: Dean S. Volenberg

There was a lot of variability in primary bud damage between cultivars and among different vineyards of Norton (Table 1). This variability tells us that it is very important to evaluate bud damage of each cultivar and each vineyard block.

Table 1. Primary and secondary bud survival of selected grape cultivars, cane wood collected on Jan. 19, 2023.
Cultivar1 Dead primary
buds (%)		 Dead secondary
buds (%)
Chambourcin 63 NA2
Chardonel 60 NA
Concord 40 13
Norton vineyard 1 12 NA
Norton vineyard 2 21 NA
Norton vineyard 3 45 NA
Vidal blanc 76 NA
Vignoles 25 NA
Average 43 9

1 A total of 10 canes with 5 to 6 buds per cane were evaluated per cultivar.

2 NA represents that secondary buds were not evaluated.


How to Evaluate Grape Buds

See the GWI article Determinging Cold-Injury to Grape Buds

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If you would like more information on IPM in grapes, please contact Dean Volenberg at 573-882-0476 (office) 573-473-0374 (mobile) or volenbergd@missouri.edu

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