Monday, March 26, 2012

Cold returns for a few days


The cold has returned to Wisconsin.   Last night we got down to about 26F.    Some buds may have already seen some damage.  At least foch and Lacrescent had already approached full swell.


Below is a nice table that shows critical temperatures for bud survival.  The table below was originally on the Michigan State University Extension web site.    That link is now dead.   (I will gladly link to another source if someone has it.)



CRITICAL TEMPERATURES FOR GRAPES
Growth Stage Description
No Damage
10% Kill
50%
Kill
90%
Kill
 
Dormant Bud not swollen.  
Varies with conditions.
First Swell Early swell,
bud brown,
no color.
 
13
7
-3
Early Swell - Doe skin
Full Swell Late Swell, swollen bud looks pink.  
26
21
10
Late bud swell shows a hint of pink
Bud Burst Leaves at tip of bud separate.
30
28
25
16
Bud Burst is when the leaves at the tip of the bud start to separate
First Leaf One leaf out at 90° to the stem.
30
28.5
27
21
When one leaf is 90 degrees from the stem
Second Leaf Two leaves out, 90° to the stem.
30
29
28
22
When 2 leaves are 90 degrees from the stem
Third Leaf Three leaves out, 90° to the stem.  
28
 
26
When 3 leaves are 90 degrees from the stem (This isn't a concord shoot).
Fourth Leaf Four leaves out at 90° to the stem.  
28
 
27
 

(The above table and photos originally from Michigan State University Extension) 

I believe the 10% and 90% kill numbers originally came from Rutgers and refers to Wine grapes.   The 50% kill numbers come from Washington State University and refer to concord grapes.  I do not know the accuracy of the numbers with respect to cold hardy vines such as French Hybrids, University of Minnesota cultivars, or Swenson cultivars.   It is interesting none the less.  

3 comments:

Anonymous said...
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Anonymous said...

I very much enjoyed reading ALL of your blogs .... this is because my husband and I are just now starting a vineyard in Virginia. We bought a farm two years ago ... and decided to put in 3000 vines on about 4 acres of hilly terrain. We've been working with a local commerical vineyard/winery and Virginia Tech folks. In late April, about a dozen friends will arrive for a weekend of planting. My husband thinks each person can plant a vine every 5 minutes .... as a farm kid, I have told him he is "dreaming". We are putting in only two types of vines: Viognier (2000 plants from Vintage Nursery in California) and Norton (1000 plants from Chrysalis Vineyard in Virginia). At any length, I thoroughly enjoyed reading your posts - know I have learned aa ton from you already - and just wanted to thank you for sharing your experiences with those of us out here who share the dream of owning a vineyard.
Best wishes,
Sandi Gauthier
Gauthier Vineyard LLC
Barhamsville, Virignia

Ed Hardy cipő said...
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