The bountiful natural terroir of Oregon has left many vineyards with excessive vegetative growth. High vigor can lead to a host of deleterious effects on grape and wine quality. Many grapegrowers annually employ intensive remedial canopy management techniques in response to high-vigor issues. The speakers in this session will address perennial vigor management strategies. From New Mexico State University, Dr. Gill Giese will share results from a long-term study of complete vineyard floor cover cropping and root pruning. From the University of Georgia, Dr. Cain Hickey will discuss results from research on the use of root restriction and rootstocks as a vigor management tool.

1. Root pruning, Intra-row
Ground Cover and
Cabernet Sauvignon
Gill Giese
Ciro Velasco-Cruz
February 20, 21 2018
Portland, OR

2. Today’s talk
• Context
• Premise and study conditions
• Root pruning and ground covers
• Results and Discussion
• What?
• Ground cover agronomy
• Vine reaction
• Berry composition
• Why?
• Vine root reaction
• Water
• Nitrogen
• Impacts

3. Charlotte
Raleigh
Durham
Greensboro
Winston-Salem
Asheville
North Carolina Vineyards
0 75 15037.5 Miles
Vineyard or Winery
Context: experimental vineyard
Yadkin Valley AVA, Surry County, NC elev. ~ 1080’
~ 186 wineries
~ 525 vineyards
~ 2,300 acres of bunch (non-muscadine) grapes

4. Monthly
maximum
temperatures
(degrees Fo)
Growing Degree Days oF
Salem, OR = 2385 (2005 to 2017)
Medford, OR = 3237 (2001 to 2013)
Dobson, NC = 3634 (2005 to 2011)
0
1
2
3
4
5
6
7
8
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Precipitation(inches/month)
Salem, OR
Medford, OR
Dobson, NC
30
40
50
60
70
80
90
100
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
Temperature(Fo)
Salem, OR
Medford, OR
Dobson, NC
Monthly
precipitation
(inches)
Context: North Carolina and Oregon
~12 ft
Fairview complex clay loam,
(0.75 – 1.50 m rooting depth),
well drained, kaolinitic, mesic,
Typic Kanhapludults

5. Excessive vigor ?

6. Experimental background
• Problem: excessive vine vigor
• Hypothesis: intra-row ground cover and root
pruning would limit water and
nitrogen, reduce vine vigor
• Objectives:
• Assess agronomic performance of ground covers
• Describe and quantify treatment effects on vine
growth, shoots, roots, berry and wine parameters
• Long term treatment effect on vineyard?

7. B B B B G 6 6 6 6 G G 6 6 6 6 G B B B B
buffer row
B B B B G 3 3 3 3 G G 3 3 3 3 G B B B B
buffer row
B B B B G 5 5 5 5 G G 5 5 5 5 G B B B B
buffer row
B B B B G 4 4 4 4 G G 4 4 4 4 G B B B B
buffer row
B B B B G 2 2 2 2 G G 2 2 2 2 G B B B B
buffer row
B B B B G 1 1 1 1 G G 1 1 1 1 G B B B B
buffer row
Block (REP) One
TRT 1 – KY-31 fescue TRT 4 – Orchardgrass
TRT 2 – Aurora Gold fescue TRT 5 – Elite II fescue
TRT 3 – Perennial ryegrass TRT 6 – Herbicide
Experimental design: RCBD, six replications

8. KY-31 Fescue
Perennial Ryegrass
Aurora Gold Fescue
Orchardgrass
Elite II Fescue

9. Root pruning

10. Ground cover biomass
2007 2008 2009 2010 2011
Mg DM ha -1
Cover crop Dec Oct June Oct Oct Mean
KY-31 fescue 3.10 a 2.21 a 1.23 ab 3.40 ab 2.44 a 2.22 a
Aurora Gold fescue 2.90 a 2.65 a 1.22 ab 3.56 ab 2.03 ab 1.97 ab
Perennial ryegrass 0.69 c 0.76 b 0.86 b 1.97 b 0.93 c 0.95 d
Orchardgrass 2.23 ab 1.09 b 1.33 a 2.49 ab 1.17 bc 1.59 c
Elite II fescue 1.72 b 1.44 b 0.86 b 3.75 a 2.08 ab 1.75 bc
Main effects and interactions
Ground cover <0.0001
Year_month <0.0001
Ground cover x Year_month <0.0001

11. Ground cover stand density, 2008, 2010
(higher number = greater density, fewer weeds)

12. Shoot growth rate (cm/day), 2006
2006
11-20
May
20-29
May
29 May -
9 Jun
9-20
Jun
20-29
Jun
Ground cover 0.0383 ns 0.0046 0.0033 ns
Root pruning ns 0.0019 0.0004 <0.0001 <0.0001
Ground cover x root pruning ns ns ns ns ns
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
11-20
May
20-29
May
29 May-
9 Jun
9-20
Jun
20-29
Jun
Shootgrowthrate(cm/day)
KY-31 fescue
Perennial ryegrass
Orchardgrass
Elite II fescue
Herbicide strip
Non root pruned
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
11-20
May
20-29
May
29 May-
9 Jun
9-20
Jun
20-29
Jun
Shootgrowthrate(cm/day)
Root pruned
a
a
a
a
b
b
Shoot growth rate
(cm/day)
May to June
NRP
Herbicide = 3.22
Grass = 2.62
RP
Herbicide = 2.96
Grass = 2.08

13. Pruning weights (kg/m), 2005 to 2017
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Pruningwt.(kg/meterofcanopy)
Herbicide non-root pruned Herbicide root pruned
KY-31 fescue non-root pruned KY-31 fescue root pruned
Elite II fescue non-root pruned Elite II fescue root pruned
“drought” year
no summer hedging
new cordons

14. Percentage pruning weight (kg/m) change, 2005 to 2009
Grass plots Herbicide plots % reduction due to:
RP NRP RP NRP Grass RP Grass + RP
2005 1.64 1.99 2.01 2.16 8 7 24
2006 1.09 1.54 1.75 1.91 19 8 43
2007 0.66 1.06 1.09 1.15 8 5 43
2008 0.93 1.36 1.41 1.52 11 7 39
2009 1.00 1.47 1.66 2.02 27 18 50
Mean 1.06 1.48 1.58 1.75 14.6 9
% change
‘05 to ‘09
% change
‘05 to ‘09
↓39% ↓26% ↓17% ↓6%

15. Percent change in crop load
(Ravaz index), 2005 to 2009
Spring 2016
* vines grown with herbicide strip = 2.77 crop load

16. Vine yield (kg/vine), 2005 to 2011
Cover crop Root Pruning 2005 2006 2007 2008 2009 2010 2011 Mean 2017
KY-31 fescue
RP 4.51 7.11 3.22 3.49 3.63 3.40 4.11 4.21 b 2.95
NRP 4.24 7.51 4.01 4.05 5.05 4.36 5.02 4.89 a 2.42
Mean 4.38 7.31 3.61 3.77 4.34 3.88 4.57 2.68
Aurora Gold fescue
RP 5.11 8.82 4.30 4.15 4.35 4.05 4.57 5.05
NRP 4.66 8.07 4.50 4.74 5.28 5.05 5.13 5.34
Mean 4.89 8.44 4.40 4.45 4.82 4.55 4.84
Perennial ryegrass
RP 4.87 7.61 3.33 3.61 4.20 4.17 5.22 4.73 b
NRP 4.83 7.98 4.36 4.81 5.38 4.76 5.12 5.32 a
Mean 4.85 7.79 3.84 4.21 4.83 4.47 5.17
Orchardgrass
RP 4.50 7.25 3.32 3.58 3.62 3.73 4.74 4.40 b
NRP 4.79 7.82 4.08 4.57 4.99 4.36 5.27 5.13 a
Mean 4.64 7.54 3.70 4.08 4.31 4.05 5.07
Elite II fescue
RP 4.91 7.62 3.86 4.00 3.67 3.59 5.10 4.68 2.96
NRP 4.68 7.94 4.43 5.12 4.76 4.20 4.22 5.06 2.66
Mean 4.80 7.78 4.15 4.56 4.21 3.90 4.68 2.82
Herbicide strip
RP 4.99 8.73 4.45 3.56 4.45 4.82 4.71 5.10 3.31
NRP 4.39 7.91 4.17 4.16 4.45 4.30 4.82 4.89 3.08
Mean 4.69 8.32 4.31 3.87 4.45 4.56 4.76 3.19

17. Root extraction
2008, 2010

18. Root intercept quantification
2008, 2010
root pruned
non-root pruned
“broom” like growth root reaction

19. Root distribution as a function of soil depth, Y = (1- ßd)
May 2008
Cumulative fraction of total root biomass at 0-100 cm soil depth (%)
Ground cover 0-20 cm 20-40 cm 40-60 cm 60-80 cm 80-100 cm ßd
KY-31 fescue 54 87 96 99 100 0.9566 c
Herbicide strip 35 72 84 94 100 0.9701 b
October 2010
Cumulative fraction of total root biomass at 0-100 cm soil depth (%)
Ground cover 0-20 cm 20-40 cm 40-60 cm 60-80 cm 80-100 cm ßd
KY-31 fescue 22 60 76 87 100 0.9776 a
Herbicide strip 20 50 69 87 100 0.9795 a

20. Soil core extraction, 2014

21. Comparison of methods to determine root biomass
distribution
R² = 0.82
0
20
40
60
80
100
120
0 0.25 0.5 0.75 1 1.25
Depth(cm)
Root biomass (g)
2008, 2010
R² = 0.5442
0
20
40
60
80
100
120
0 0.25 0.5 0.75 1 1.25
Depth(cm)
Root biomass (g)
2014
soil monolith extraction soil core extraction

22. Root length density, 2014
0 0.5 1 1.5
20
40
60
80
100
120
Fine--Root length density (mm/cm3)
Depth(cm)
KY-31 fescue
Elite II
Herbicide strip
0 0.5 1 1.5
20
40
60
80
100
120
Depth(cm)
KY-31 fescue
Elite II
Herbicide strip
Coarse—Root Length density (mm/cm3)

23. Soil volumetric water content (%)

24. Total petiole N
@ bloom
(% of dry wt)
Fescue KY-31
Aurora
Fescue
Perennial
Ryegrass
Orchardgrass
Elite II
Fescue
Herbicide
Control
Mean
2007
RP 0.83* 0.80 0.80* 0.80* 0.78 0.78 0.80 *
NRP 0.95* 0.84 0.96* 0.91* 0.85 0.80 0.88 *
Mean 0.89 0.82 0.88 0.85 0.82 0.79
* Root pruning (Pr>F) 0.0078
2009
RP 0.94 0.86 0.85 0.94 0.83 1.07 0.92
NRP 0.98 0.86 0.96 0.85 0.89 1.02 0.93
Mean 0.96ab 0.86c 0.91bc 0.90bc 0.86c 1.04a
* Cover crop (Pr>F) 0.0016
2010
RP 1.10 * 1.08 1.15 * 1.14 1.16 * 1.30 1.15*
NRP 1.29 * 1.19 1.35 * 1.31 1.37 * 1.31 1.30 *
Mean 1.19 1.13 1.25 1.22 1.26 1.30
* Root pruning (Pr>F) 0.0002
• Petioles collected at bloom
recommended N% = 1.2 to 2.1%
Ground Cover 2007 2009 2010 2014 2017
KY-31 fescue 0.89 0.96 1.19 0.93 1.02
Elite II fescue 0.82 0.86 1.26 1.11 1.15
Herbicide strip 0.79 1.04 1.30 1.09 1.21

25. Analysis of covariance: leaf petiole
N% to pruning weights (kg/m),
2007, 2009 and 2010
Regression of leaf petiole N% to
pruning weights 2007, 2009,
2010, 2014 and 2017

26. Slope, intercept comparisons of leaf
petiole N % and pruning weights (kg/m)
p values for intercept comparisons
Cover crop
Root pruning
KY-31
fescue NRP
KY-31
fescue RP
Elite II
fescue NRP
Elite II
fescue RP
Herbicide
strip NRP
Herbicide
strip RP
KY-31 fescue NRP --- 0.0296 0.6573 0.0061 0.8581 0.3590
KY-31 fescue RP --- 0.0053 0.5934 0.0349 0.1595
Elite II fescue NRP --- 0.0006 0.5036 0.1372
Elite II fescue RP --- 0.0068 0.0454
Herbicide strip NRP --- 0.4350
Herbicide strip RP ---
p values for slope comparisons
KY-31
fescue NRP
KY-31
fescue RP
Elite II
fescue NRP
Elite II
fescue RP
Herbicide
strip NRP
Herbicide
strip RP
KY-31 fescue NRP --- 0.1246 0.4497 0.0329 0.4405 0.2011
KY-31 fescue RP --- 0.0206 0.5739 0.3746 0.6636
Elite II fescue NRP --- 0.0033 0.1032 0.0289
Elite II fescue RP --- 0.1311 0.2880
Herbicide strip NRP --- 0.5988
Herbicide strip RP ---

27. Berry nitrogen at harvest (YAN, ppm)
* Desired range of YAN at harvest ~ 140 to 180 ppm
2009 2010 2011 2017
KY-31
fescue
RP 149 94 184 143
NRP 176 149 189 137
Mean 163 b 121 b 186 140
Elite II
fescue
RP -- -- 164 153
NRP -- -- 171 140
Mean -- -- 167 147
Herbicide
Strip
RP 204 180 173 167
NRP 216 345 181 172
Mean 210 a 263 a 178 169

28. Pruning time
(minutes/vine)
* Exclusive of labor, references for herbicide pricing: Vinesmith.com, Winegrape Herbicide Guide 2017/2018 and
University of Florida IFAS extension, http://edis.ifas.ufl.edu/wg056 accessed: 2/2/2018, **100 acre assumes 50% treated
2017
KY-31
fescue
RP 2.58
NRP 3.36
Mean 2.97
Elite II
fescue
RP 2.98
NRP 3.04
Mean 3.02
Herbicide
Strip
RP 2.87
NRP 3.08
Mean 2.98
2005 to 2017*
1 acre
100 acre
vineyard**
Herbicide
strip
Glyphosate 16.00 800.00
Chateau (2x) 120.00 6,000.00
TOTAL / ACRE 136.00 6,800.00
Glyphosate 16.00 800.00
Alion (1x) 75.00 3,750.00
TOTAL / ACRE 91.00 4,550.00
pre harvest Gramoxone? 9.00 450.00
Ground cover
Annual estimated herbicide costs
(2017 prices)

29. Impacts
• Intra-row ground cover: reduced pruning weights, vine vigor and size
and can maintain vine size when RP no longer applied
• Treatment effect linked to vine N status, monitor N closely
• Minimal yield penalty with intra-row ground cover
• With different crop load?
• With unhedged vines?
• Elite II fescue superior to other tested grasses
• Root pruning…works, but cost considerations?
• Other benefits:
• Herbicide use reduction
• Reduction of cultural costs?
• Erosion mitigation?

30. • Giese, G., C. Velasco-Cruz, L. Roberts, J. Heitman, and T.K. Wolf. 2014. Complete vineyard floor cover crops
beneficially limit grapevine vegetative growth. Sci. Hortic. 170:256-266.
• Giese, G., T.K. Wolf, C. Velasco-Cruz, L. Roberts and J. Heitman. 2015. Cover crop and root pruning impacts
on vegetative growth, crop yield components, and grape composition of Cabernet Sauvignon. Am. J. Enol.
Vitic. 66:212-226.
• Giese, G., T.K. Wolf, C. Velasco-Cruz, and L. Roberts. 2016. Cover crop and root pruning effects on the
rooting pattern of SO4 rootstock grafted to Cabernet Sauvignon. Am. J. Enol. Vitic 67:105-115.
• Holland, S., A. Howard, J.L. Heitman, T.J. Sauer, W. Giese, T.B. Sutton, N. Agam, A. Ben-Gal, and J.L. Havlin.
2014. Implications of an interrow fescue cover crop for below-canopy water dynamics in a vineyard. Agron.
J. 106:1267-1274.
• Centinari M. et al. 2013, Cover crop water use in relation to vineyard floor management practices. Am. J.
Enol. Vitic. 64:
• Smart, D. R., E. Schwass, A. Lasko, and L. Morano. 2006b. Grapevine rooting patterns: a comprehensive
analysis and a review. Am. J. Enol. Vitic. 57:89-104
References

31. Acknowledgements
Dr. Tony Wolf, Virginia Tech
Dr. Molly Kelly, Penn State University
Dr. Ciro Velasco-Cruz
Dr. Josh Heitman and Mr. Adam Howard, North Carolina State University
Dr. Lucas Roberts, Amazon Inc.
Mary Simmons, Miguel, Julio, Vidal, Ernesto, and Luis Sanchez @ Shelton Vineyards
Funding or support:
New Mexico State University
Virginia Tech
Shelton Vineyards, Dobson NC
North Carolina Wine and Grape Council
Virginia Wine Board

32. Gill Giese
Viticulture Extension Specialist
ggiese@nmsu.edu
Thank you for your attention!
Questions?