REPLACING HERBICIDES WITH GROUNDCOVERS IN THE VINEYARD Benjamin A. Loseke

Special Thanks to: Dr. Paul Read, Dr. Ellen Paparozzi, Dr. Erin Blankenship, Dr. Chuck Francis, Dr. Brian Wardlow, Steve Gamet, Eric Nelson, Scott Dvorak, Dave Stock and Mike Fritz Benefits of using groundcovers in the vineyard

■ Reduced herbicide usage ■ Reduced erosion ■ Increased soil fertility, water holding capacity and structure ■ Reduced soil compaction ■ Increased Biodiversity ■ Regulate vine growth ■ Improved air and water quality ■ Nitrogen fixation Project objectives

■ How do 4 different groundcover mixes planted in the alleyways and in rows compete with newly planted vines for water? ■ Do groundcovers established simultaneously with vineyard planting have negative effects on vine growth? ■ What impact do groundcovers have on vine growth, bud break, fruit quality and wine quality? ■ How quickly do the groundcovers establish? ■ Can Infrared thermography (IRT) be used to assess grapevine water status using the crop water stress index (CWSI)? ■ Will a thermal camera affordable to a grower be sensitive enough to measure water stress? ■ Do beneficial insect populations increase as a result? BEGINNING OF PROJECT

Vineyard establishment

Irrigation Groundcover Planting

Germination Establishment Where we didn’t plant Groundcovers Groundcover Treatments ■ Treatment 1 – Roadside Mix (Stock Seed Farms) ■ Western Yarrow, Birdsfoot Trefoil, Dutch Clover Groundcover Treatments

■ Treatment 2 – Custom Native Grass Mix ■ Hard Fescue, Sheeps Fescue, Sideoats Grama, Buffalograss, Blue Grama Groundcover Treatments

■ Treatment 3 – Vineyard/Orchard Mix (Stock Seed Farms) ■ KY Bluegrass, White Clover, Red Fescue, Hard Fescue, Chewings Fescue, P Rye Groundcover Treatments ■ Treatment 4 ■ Texoka Buffalograss Groundcover Treatments ■ Control ■ Natural Vegetation + Weed Free Strip Beneath Vines Data Collected – 2014, 2015, 2016 ■ Soil Samples (all years) ■ Groundcover Rate of Establishment (2014) ■ Vine Length (2014) ■ Pruning Weights (2015 & 2016) ■ Leaf Water Potential, i.e. Plant Water Status (2015, 2016) ■ Crop Water Stress Index (2015, 2016) – Leaf temperature – Irradiance – Ambient air temperature – Wind speed – Relative humidity ■ Bud Break (2016) ■ Harvest Data (2016) RESULTS (DATA OVERLOAD) Rate of GC establishment (2014)

Rate of Groundcover Establishment (Alleyway) 1

0.9

0.8

0.7

0.6

0.5 %cover 0.4

0.3

0.2

0.1

0 7/5/2014 7/10/2014 7/15/2014 7/20/2014 7/25/2014 7/30/2014 8/4/2014 8/9/2014 8/14/2014 8/19/2014 8/24/2014

Treatment 1 Treatment 2 Treatment 3 Treatment 5 Treatment 6 Shoot Lengths (2014)

Year One Primary Shoot Lengths 120

100

80

60 Wire Height

Shootlength(inches) 40

20

0 Treatment 1 Treatment 2 Treatment 3 Treatment 4 Control Pruning weights 2014 & 2015

Pruning Weights (2014 Growing Season) Pruning Weights (2015 Growing Season) 0.35 0.6

0.3 0.5

0.25

0.4

) ) lbs lbs 0.2 0.3

0.15 Weight ( Weight Weight ( Weight 0.2 0.1

0.05 0.1

0 0 TREAT 1 TREAT 2 TREAT 3 TREAT 4 TREAT 6 TREAT 1 TREAT 2 TREAT 3 TREAT 4 TREAT 6

??? Date of Bud Break (2016)

Julian Days until Bud Break 107 106 105 104 103

102 Julian daysJulian 101 100 99 98 Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 (control) Water Competition Summer 2015

Mean Leaf Water Potential of all Reps on Each Collection Date 0.00 TREATMENT 1 TREATMENT 2 TREATMENT 3 TREATMENT 4 TREATMENT 6

-2.00

-4.00 bars) - 30-Jun 7-Jul -6.00 17-Jul 29-Jul

5-Aug High Temp Water Water potential (

-8.00 100 90 80 70 60 50 -10.00 40 High Temp Temp(F) 30 20 10 0 -12.00 Date Measured Water Competition Summer 2016

Mean Leaf Water Potential 07/06/2016 Mean Leaf Water Potential 07/12/2016 -6 -5.2 Trt 1 Trt 2 Trt 3 Trt 4 Control Trt 1 Trt 2 Trt 3 Trt 4 Control -5.4 -6.2 -5.6 -6.4 -5.8

-6.6 -6

-6.8 -6.2 -6.4 -7 -6.6 -7.2 -6.8

-7.4 -7

-7.6 Avg Temp - 88°F -7.2 Avg Temp - 83°F

Mean Leaf Water Potential 08/10/2016 Mean Leaf Water Potential 08/01/2016 0.00 0 T1 T2 T3 T4 T6 Trt 1 Trt 2 Trt 3 Trt 4 Control -1.00 -1 -2.00 -2 -3.00 -3 -4.00 -4 -5.00 -5 -6.00 -6 -7.00 -7 -8.00 -8 -9.00 -9 Avg Temp - 81°F Avg Temp - 89°F Baseline for “water stressed” Edelweiss Vines

LWP of Dried Potted 'Edelweiss' Grapevines 0 Control 2 Days 4 Days 6 Days 8 Days 10 Days 12 Days 14 Days

-2

-4

-6 bars)

- -8 LWP ( LWP a -10 a a a a -12 b b -14 -12 bars b

-16 Days without water Harvest Results (2016)

Average Yield (g)/Plant Average Cluster Weight (g) 4000.00 64.00

3500.00 62.00

3000.00 60.00

2500.00 58.00

2000.00 56.00

Weight Weight (g) Weight (g) 1500.00 54.00

1000.00 52.00

500.00 50.00

0.00 48.00 Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 (control) Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 (control)

Harvest Caveat: Estimated 50% Crop Loss from Herbicide Drift Harvest Results (2016)

pH TA 3.25 10.40

3.20 10.20 10.00 3.15 9.80 3.10 9.60

3.05 9.40

3.00 9.20 Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 (control) (control)

°Brix 17.00

16.50

16.00

15.50

15.00

14.50

14.00 Trt 1 Trt 2 Trt 3 Trt 4 Trt 6 (control) Infrared Thermography ■ Idea: as plants begin to become water stressed their leaf temperature will increase as stomata close and transpiration slows ■ Thermal cameras are able to detect this change ■ Using the leaf temperature we can plug the values into the crop water stress index (CWSI) for a standard water stress level between 0 and 1 LWP and CWSI Correlation

CWSI vs. LWP on All Sampling Dates 0 -0.05 0.15 0.35 0.55 0.75 0.95 1.15 -2 y = -3.6539x - 1.8829 R² = 0.1613

bars) -4 - y = -1.0155x - 6.3225 -6 R² = 0.0222

-8 y = 0.767x - 9.7469 R² = 0.0046 -10 y = 1.6704x - 9.2328 R² = 0.0341 y = 0.6206x - 10.313 R² = 0.0093 -12 y = -6.8465x - 4.5898 R² = 0.2303 Leaf Leaf water potential ( -14

-16 CWSI

30-Jun 7-Jul 14-Jul 29-Jul 5-Aug 12-Aug Linear (30-Jun) Linear (7-Jul) Linear (14-Jul) Linear (29-Jul) Linear (5-Aug) Linear (12-Aug) https://www.youtube.com/watch?v=bqpAk3OHDe4

Preliminary* Recommendations

■ Results suggest planting groundcovers in year 2 after vines have had one year to establish ■ Groundcovers should be taken care of as if they provided economic value to the vineyard (i.e. irrigation, fertilization, etc.) ■ Native grass groundcovers appear to stress the vines the most ■ Final Recommendation: TO ENHANCE VINEYARD SUSTAINABLITIY, PLANT SOMETHING! Questions