Retraining a winter/cold damaged vine

Fifteen year old 'Mission' vine with winter/cold damage. Regrowth from trunk and latent buds in evidence. Albuquerque Botanical Garden/Heritage Farm, June 19, 2020, Albuquerque, NM. 

'Mission' grapevines on left and 'Glenora' grapevines on right.
Albuquerque Botanical Garden/Heritage Farm, June 19, 2020, Albuquerque, NM.

Close up of damaged, split vine trunk on the cultivar 'Mission' at Albuquerque Botanical Garden/Heritage Farm, June 19, 2020, Albuquerque, NM.

July 26, 2020

NOTES: Retraining Cold Damaged Vines*

 

1.     Replacing damaged trunks:

a.     Multiple trunks spread risk of injury

b.     Double trunks: leave spur to produce ‘replacement’ trunk

c.     Following injury: some trunks die immediately and some die over 2-5 years

2.     Bud numbers

a.     Crop if possible to temper or tamp-down vegetative growth, without crop remaining and newly formed shoots will grow more vigorously

b.     Leave compromised trunks if needed, to achieve bud numbers

3.     Crown gall

a.     No hurry to remove crown gall affected tissues, support trunk/bud numbers

b.     Crown gall bacteria is already present systemically in the vine. Thus, no need to hurry to remove it. It can be pruned out next spring

4.     Suckers

a.     Growth from below ground, referred to as “suckers”

b.     Suckers increase leaf area, part of vine’s ‘survival response’ to feed root system.

c.     Sucker number increase when top growth (shoots and leaves) are damaged and missing. Top growth normally produces the hormone auxin. Auxin inhibits suckers from sprouting and growing. A proliferation of sucker growth at base of the vine indicates the vine has been injured …typically, from cold temperatures.

5.     Cane size desired:

a.     7-9 mm, slightly diameter than a #2 pencil.

b.     Larger diameter indicative of “bull” canes with excessive vegetative growth.  Smaller diameter canes too weak for sufficient growth and support of healthy buds and crop.

6.     Clean cuts

a.     Dull pruner cuts look bad

b.     Sloppy, tearing cuts, encourage wood rotting disease such as Eutypa

7.     Training stakes

a.     Place stake close to vine trunk and clip to cordon wire to hold it securely in place.

b.     Stakes encourage straight trunks and benefit mechanization and vineyard operations in general.

8.     Nitrogen and fertilizer application in year of recovery:

a.     ~ 90% of vine’s N requirement is derived from reserves in woody tissues and soil nitrification

b.     No need to fertilize winter/cold damaged vines as you retrain…skipping a year ok…unless obvious deficiencies present themselves…which is not likely.

* excerpted and summarized from:
Winter Injury to Grapevines and Methods of Protection, Extension Bulletin E2930, Michigan State University Extension, T. J. Zabadal, I. E. Dami, M.C. Goffinet, T.E. Martinson, M.L. Chien. 2007.

Winter Injury to Grapevines and Methods of Protection