2017 Oregon Wine Symposium

Coping Strategies for a Warmer

Climate : Irrigation/Canopy

Management

Larry E. Williams Kearney Agricultural Research and Extension Center

and Department of Viticulture and Enology

UC-Davis

Vineyard Irrigation Strategies should be

knowledge based:

• What is vineyard ETc or do you have an estimate of ETc?

• How much water is actually applied each year? How is that measured?

• How much water in the soil profile is available for consumptive water use? Do you have a means to determine that amount or asses vine water status?

• How does vineyard design (row spacing and trellis type) affect vineyard ETc?

• What fraction of seasonal ETc is used between budbreak and bloom, veraison or harvest?

• Can RDI or SDI be used to minimize water use while maintaining yields of high quality?

Performance Metrics and the

California Sustainable

Winegrowing Program:

“You can’t manage what you

don’t measure”

California Sustainable

Winegrowing Alliance

Within the drip line water meter.

Important irrigation management decisions

• When should one initiate irrigations at the

beginning of the season?

• How much water should one apply?

• How does the design of your irrigation

system affect the ability to irrigate your

vineyards?

• How reliable is your water supply?

• Are there deficit irrigation practices to

minimize production loss and maximize

fruit quality?

2017 Oregon Wine Symposium

Coping Strategies for a Warmer Climate: Irrigation/Canopy

Management

Vineyard Irrigation Scheduling - Basics

Larry E. Williams

Department of Viticulture and Enology

University of California-Davis

Kearney Agricultural Research and Extension Center

9240 S. Riverbend Ave., Parlier CA 93648

lewilliams@ucanr.edu

“Goal of irrigation management” Mark Battany

• Your goal should be to grow vines with a uniform degree and pattern of water stress every season (the degree of stress determined by the grower).

• To do this, you need to adjust irrigation timing and amounts to take into account unique growing conditions in any given season.

• Weather (evaporative demand and temperature) is the variable component that exerts the most influence on irrigation requirements during the season.

ETc = ETo x Kc

The above equation estimates

vineyard water use at 100% of ETc.

ETo is reference ET (measure of

evaporative demand at a location).

This takes into account the weather

factors. The Kc is defined in the

next slide.

Crop Coefficient (Kc)

• The fraction of water used by a specific

crop compared to that of ETo at a given

location

• Kc = ETc / ETo

• The Kc depends upon stage of crop

development, degree of cover, crop height

and canopy resistance.

• Calculated as a function of degree-days

Reliable crop coefficients should take

the following into account:

• Seasonal growth of grapevines

• Final canopy size, which is a function of

trellis design

• Row spacing (the closer the row spacing

the greater the water use per acre)

• Possible differences in growth (canopy

size) due to cultivar and/or rootstock

One can get a reliable estimate of the

seasonal crop coefficient for

vineyards by measuring the amount

of shade cast on the ground beneath

the canopy around solar noon

throughout the growing season. The

equation is:

Kc = 0.017 * % shaded area (% shaded area is measured shaded area per vine divided by area per vine

in the vineyard)

(percent shaded area is a whole number) (Williams and Ayars (2005) Agric. For. Meteor. 132:201-211)

Trellis/ Row Spacing

Canopy type (m) Crop coefficient equation

VSP 1.83 (6 ft.) Kc = 0.87/(1+ e(-(x – 525)/301))

2.13 (7 ft.) Kc = 0.74/(1+ e(-(x – 525)/301))

2.44 (8 ft.) Kc = 0.65/(1+ e(-(x – 525)/301))

2.74 (9 ft.) Kc = 0.58/(1+ e(-(x – 525)/301))

3.05 (10 ft.) Kc = 0.52/(1+ e(-(x – 525)/301))

CA Sprawl 3.05 (10 ft.) Kc = 0.84/(1+ e(-(x – 325)/105))

3.35 (11 ft.) Kc = 0.76/(1+ e(-(x – 325)/105))

3.66 (12 ft.) Kc = 0.70/(1+ e(-(x – 325)/105))

Quad-cordons 3.35 (11 ft.) Kc = 0.93/(1+ e(-(x – 300)/175))

(or GDC/Wye) 3.66 (12 ft.) Kc = 0.85/(1+ e(-(x – 300)/175))

Lyre Types 2.74 (9 ft.) Kc = 0.93/(1 + e(-(x – 300)/150))

or ‘V’ 3.05 (10 ft.) Kc = 0.84/(1 + e(-(x – 300)/150))

3.35 11 ft.) Kc = 0.76/(1 + e(-(x – 300)/150))

3.66 (12 ft.) Kc = 0.70/(1 + e(-(x – 300)/150))

The effect of row spacing on estimated seasonal Kc values for a VSP trellis system, a California Sprawl

type canopy, quadrilateral cordon trained vines and Lyre type canopies. The x value in the equation is

degree-days (base of 10oC) from a starting point. The e value in the equation is 2.71828. Note that row

spacing only changes the numerator in the equation, the maximum Kc value.

Possible topics covered: • How to deal with less than full soil moisture

profile at beginning of season

• When best to initiate irrigation

• How best to monitor plant water status and soil moisture

• How to design irrigation strategies for different soil profiles and is it better to irrigate deeply and infrequently or more frequently and shallower

• How to deal with heat spikes

• How to deal with the possibility of losing water supply before harvest.

Vineyard

evapotranspiration:

ETc 101

‘The Basics’

Definitions • Transpiration – evaporation of water that has

passed through a plant

• Stomatal conductance – a measure of how open or

closed the stomata are

• Crop evapotranspiration (ETc) – the total process of

water transfer to the atmosphere by a specific crop

(i.e. grapevines) to include soil evaporation

• Reference ET (ETo) – a measure of the evaporative

demand in a region (can be obtained from CIMIS)

• Leaf water potential – a measure of the water status

of plants (units expressed in bars or megapascals

(MPa), 10 bars = 1.0 MPa)

Calculation of Evapotranspiration (ET)

Δ (Rn – G) + ρcpδe/ra

Ep = __________________________

Δ + γ (1 + rc/ra)

Δ = temp. derivate of saturated vapor pressure function (Pa K-1)

Rn = net radiation (W m-2)

G = rate of change of energy storage (W m-2)

ρ = density of dry air (1.2 kg m-2)

= latent heat of vaporization (2465 J g-1)

cp = specific heat of the air at constant pressure (1005 J kg-1 K-1)

δe = vapor pressure deficit (Pa) (as RH decreases VPD increases)

ra = aerodynamic resistance (s m-1)

γ = psychrometric ‘constant’ (66 Pa K-1)

rc = canopy resistance of stand (s m-1)

Environmental Factors Affecting ET

• As Net Radiation increases, ET

increases (it is the driving force

of ET)

• As the VPD increases (or as RH

decreases), ET increases

• As wind increases, ET increases

A weighing lysimeter

7 July, 1993 14.7 gal/day

max/hr 1.76 gal

No nighttime transpiration

Clouds move in

Overcast

Field Capacity

Permanent Wilting Point

Completely Dry

Available Soil

Moisture

Readily Available WaterB

Illustration of Soil Moisture TermsA

A At soil saturation the beaker would be full or overflowing. B Readily available water is considered to be ~50% of the available soil moisture.

12 gal/day

3.5 gal/day

Soil water content measured directly beneath the drip line to a depth of 5½ feet.

Readings were taken at depths of 0.23, 0.46, 0.76,

1.07,1.37 and 1.67 m (9, 18, 30, 42, 54 and 66

inches, respectively) from the soil surface.

Gra

pev

ine

wat

er u

se /

eva

po

rati

ve d

eman

d

12.1 gal/day 13.1 gal/day

4.52 gal/day 3.68 gal/day

transient cloud cover

Dr. Vinay Pagay – estimated that 32% of daily total water use was from transpiration occurring at night for Tempranillo vines grown in southern Oregon.

20 Jul 23 Jul 26 Jul 29 Jul 01 Aug 04 Aug 07 Aug

Sap

Flo

w V

elo

cit

y (

cm

hr-1

)

0

20

40

60

80

100

HRM

CHPM 18

CHPM 24

CHPM 36

Irrigation event

Sap flow velocity of Thompson Seedless grapevines in response to

the termination of irrigation. Irrigation was terminated 11 July and

irrigated again on 6 August for 3 hours (~20 gallons/vine).

Vineyard ETc is a function of the amount of light

intercepted by the canopy (also called fraction of ground cover or % shaded area).

• As the canopy develops (becomes

larger) during the season, vineyard

water use increases.

• As the trellis width increases the amount

of canopy intercepting light increases

therefore, water use increases.

• The closer the row spacing the greater

the water use per unit land area.

% shaded area is also called fraction of canopy cover

What percentage of ETc is due to vine

transpiration? How much water is lost via

soil evaporation?

Vine water use, measured with the

weighing lysimeter, was compared when

the soil surface was covered with two

layers of thick plastic versus no plastic

on the soil surface. This was done over

several years under high frequency drip

irrigation at 100% of ETc.

Lysimeter covered with

plastic to minimize soil

water evaporation.

What percentage of ETc is E or soil

evaporation?

• Lysimeter’s soil surface was covered with

plastic numerous times during the 2009

growing season (6 June to 14 Sept.).

• Grapevine water use was reduced ~ 11%

when the soil was covered with plastic

compared to bare soil (5.64 vs. 6.36

mm/day).

• The Kc was reduced from an average of

1.07 to 0.93 (13% reduction) over the 100

day period mid-season.

How to deal with less

than full soil moisture

profile at the beginning

of the season. Is it a

problem?

Dry soil at budbreak: possible

consequences

• Delayed shoot growth

• Abscission of clusters

• Reduced yield (due to smaller berries and

fewer clusters)

• “Effect of winter rainfall on yield components

and fruit green aromas of Vitis vinifera L. cv.

Merlot in California” Mendez-Costabel et al. (2014)

Austral. J. Grape Wine Res. 20:100-110.

• Irrigation wasn’t initiated until 22 and 16 May

in 2009 and 2010, respectively.

Soil water content as

a function of irrigation

treatment in a Thompson

Seedless vineyard (soil water

content at field capacity is ~22% v/v.)

Rainfall dormancy:

11/90 → BB/91 = 299* mm (11.8 in)

11/91 → BB/92 = 241 mm (9.5 in)

11/92 → BB/93 = 350 mm (13.8 in)

Δ Soil water content

11/90 → BB/91= 150 mm (5.9 in)

11/91 → BB/92 = 138 mm (5.4 in)

11/92 → BB/93 = 198 mm (7.8 in)

Upward arrows indicate date

irrigation commenced each year.

*From the 1st to end of March

(222 mm rainfall)

FC

FC

Shoot length as a function of day

of year across three years. Note

that delayed shoot growth only

occurred early on in 1991 for the

treatment irrigated at 20%

of ETc despite soil water content

for that treatment, compared to

the other three treatments. Clusters

also abscised for the 0 and 20%

ETc treatments.

*Soil matric potential for the 0.2

irrigation treatment = -76 cbar.

Same value in 1992 at same date.

*

Shoot lengths from 1991 as a function of degree-days from

budbreak. The numbers next to a data point represent the

midday leaf water potential for a particular treatment (MPa)

Question: How much does rainfall (dormant

and in-season) contribute to the water

requirements of a vineyard in the San Joaquin

valley?

Possible Answer:

The evaporation of water from the soil after a rainfall event can approach ETo for up to three days (~ 5 mm (0.2 in.) per day determined with a weighing lysimeter early in the spring). Most researchers assume that 50% of the rainfall is effective (depending upon a few more factors). Therefore, if you receive 25 mm (1 inch) of rain, you can assume ½ of that is available for the grapevines.

Soil water balance can be calculated as follows:

P + I + W – ETc – R – D = + ΔSWC

where P is precipitation, I is irrigation amount, W is the contribution of a water table via upward capillary flow, ETc is vineyard ET, R is surface runoff, D is drainage and ΔSWC is the change in soil water content between measurement dates. Effective daily rainfall:

Effective rainfall (mm) = (rainfall amount – 6.35) x 0.8

(Prichard et al., 2004)

Williams (2014, Amer. J. Enol. Vitic. 65: 159-168) has found this to be reliable for rainfall during the growing

season.

Rainfall amounts and the change in soil water content from 1

November to budbreak the following year in a vineyard at the

Kearney Agricultural Research and Extension Center near

Parlier. The soil was a Hanford fine sandy soil. Soil water

content was measured to a depth of 2.9 m in plots irrigated at

0.2, 0.6, 1.0 and 1.4 times vine water use. ETo averaged 166

mm during dormancy. (vine and row spacing = 7x11ft.)

Rainfall during dormancy:

11/90 → BB/91 = 299 mm (11.8 in)

11/91 → BB/92 = 241 mm (9.5 in)

11/92 → BB/93 = 350 mm (13.8 in)

11/93 → BB/94 = 165 mm (6.5 in)

11/94 → BB/95 = 447 mm (17.6 in) Calculated

Δ Soil water content: Effective rainfall

11/90 → BB/91 = 150 mm (50%) 138 mm (275 gal/vine)

11/91 → BB/92 = 138 mm (57%) 110 mm (220 gal/vine)

11/92 → BB/93 = 198 mm (57%) 167 mm (333 gal/vine)

11/93 → BB/94 = 61 mm (37%) 45 mm (90 gal/vine)

11/94 → BB/95 = 181 mm (40%) 192 mm (383 gal/vine)

Question: How deep in the soil

profile do grapevines use

water and what fraction of ETc

is with water derived from the

soil profile?

Access tube arrangement for Thompson Seedless vines with 2.15 m between vines and

3.51 m between rows. Tube depth is 3 m with nine tubes per site.

Chardonnay vineyard,

Carneros region in

Napa Valley (clay

loam soil).

Kearney Ag Center (vines were drip irrigated

multiple times daily at the

fraction of measured ETc

given in the graph)

SWC directly below

the in-row emitters.

Question: How much water do

grapevines use? Differences in

water use among vineyards:

effects of canopy type and row

spacing.

Several canopy types in Viticulture

Scarlet Royal vineyard on 16 September, 2014. (3.05 m (10 ft.) rows)

Estimated seasonal water use (ETc) for various

trellises on an 11-foot row spacing using

historical DDs and ETo data.

• Open gable trellis: 1,200 mm (47.2 in.)

• Two foot crossarm (Lysimeter): 907 mm (35.7 in.)

• Vines w/quad cordons: 912 mm (35.9 in.)

• CA sprawl: 785 mm (30.9 in.) (34 in. for 10 ft. row or 28 in. for 12 ft. row)

• Lyre type trellis: 779 mm (30.7 in.)

• VSP: 552 mm (21.7 in.)

Year Irrigation Soil Applied

(rain) Treatment Yield H2O H2O ETc

(t/acre) (mm) (mm) (mm)

1998 0 6.99 260 0 260 (10.2 in)

(35.5 in) 0.5 7.52 201 (66%) 105 306 (12.0 in)

1.0 7.88 165 (41%) 232 397 (15.6 in)

1999 0 4.85 b 249 0 249 (9.80 in)

(19.3 in) 0.5 6.23 a 198 (57%) 147 345 (13.6 in)

1.0 6.59 a 155 (34%) 294 449 (17.7 in)

2000 0 3.96 c -- -- -- (19.6 in) 0.5 6.81 b -- 153 -

1.0 8.14 a -- 298 -

2001 0 3.56 c -- -- -- (12.8 in) 0.5 6.06 b -- 165 -

1.0 7.31 a -- 320 -

ETc of Chardonnay grapevines as a function of irrigation

treatment and year. The separation of ETc into water

derived from the soil and that applied is also given.

260 mm = 841 l/vine (222 gal./vine) (vine x row = 5’ x 7’)

Question: How much is estimated vineyard

ET affected by year?

• Grapevine water use was estimated at one

location across several years.

• Water use was estimated for Chardonnay

grapevines on a 2.13 m (7 ft.) row spacing.

• The trellis was a VSP.

Seasonal Precipitation Estimated

Year Nov - Mar From 1 Apr DDs ETo ETc

---------- (mm) ---------- (> 10 C) ---------- (mm) ---------

1994 192 (7.6 in) 61 (2.4 in) 1408 1067 432 (17.0 in)

1995 843 (33.2 in) 47 (1.9 in) 1522 1032 447 (17.6 in)

1996 480 (18.9 in) 139 (5.5 in) 1548 1009 455 (17.9 in)

1997 522 (20.6 in) 38 (1.5 in) 1675 1066 503 (19.8 in)

1998 819 (32.2 in) 85 (3.3 in) 1369 885 346 (13.6 in)

1999 436 (17.2 in) 53 (2.1 in) 1357 988 378 (14.9 in)

2000 427 (16.8 in) 72 (2.8 in) 1446 975 410 (16.1 in)

2001 308 (12.1 in) 19 (0.7 in) 1519 1057 462 (18.2 in)

1481 1009 429 (16.9 in)

Seasonal precipitation, degree days (DDs) from 1 April

and reference ET (ETo) and estimated ETc (1 April to 1 Nov.)

of a Chardonnay vineyard in Carneros. VSP trellis w/vine x row

spacing of 5’ x 7’)

Available water to a depth of 2.75 m was estimated to be 275 mm (10.8 in) in this

vineyard (or 891 L/vine or 236 gal/vine).

ETc of 429 mm (16.9 in) is equivalent to 1390 L/vine or 368 gal/vine in this vineyard.

Question: How much is estimated vineyard

ET affected by year? Conclusions:

• The lowest value of estimated ETc (1997)

was only 69% that of the greatest (1998).

• ETo from 1998 was 83% that from 1997.

• The accumulation of DDs from 1997 were

81% that from 1997.

• The difference in ETc between the two

years were due to a combination of

differences in ETo and DDs. The

differences in DDs affected the Kc.

How can one get an estimate of

ETc in their vineyard?

Comparison of ETc determined with

a weighing lysimeter, Eddy

Covariance, Surface Renewal and

soil water budgeting.

C. Parry, T. Shapland, A. Calderon, L.

Williams and A. McElrone

SR is used to measure sensible heat flux,

and is then fed into the following energy

balance equation:

LE = RN – H – G

where LE is the latent heat flux density, RN is

the net radiation, G is the soil heat flux

density, and H is the sensible heat flux

density from SR.

Water use calculated with Surface Renewal

versus measured with a weighing lysimeter.

How much water is used

by vines as a function of

phenology throughout

the growing season?

Water use as a function of

phenology (% of total use).

Cultivar

BB

Bloom

BB

Veraison

BB

Harvest

Total

Thompson

Seedless 10 38 89 825 mm (32.5 in)

Chardonnay

(Carneros) 10 38 78 429 mm (16.9 in)

Merlot

(SJV) 10 52 82 716 mm (28.2 in)

Red Cultivars

(SJV) 10 48 78 >828 mm

(32.6 in)

How to design irrigation strategies

for different soil profiles

(different soil textures and varying

depths):

When best to initiate irrigation

and whether it is better to

irrigate deeply and infrequently

or more frequently and

shallower

Deciding when to start irrigating

There are several methods: a.) measuring the

depletion of water in the soil profile to a pre-

determined value with a neutron probe (or other

such technique), b.) water budgeting, i.e.

calculating vineyard water use and subtracting

that from the amount of water in the profile (this

requires knowledge of the water holding

capacity of the soil and effective rooting depth)

and c.) using a plant based method such as

measuring leaf water potential. All three

methods could be used with low volume or

surface irrigation.

What information is needed to

determine when to start irrigating?

• An estimate of the amount of water available in

the soil profile (this can be determined with a

neutron probe, capacitance sensors,

tensiometers, etc.) or knowledge of soil type

• Rooting depth of the vines in your vineyard (a

good estimate is ~ 1.2 to 1.5 m (4 to 5 feet) but

water extraction may take place at greater

depths.

• An irrigation event would take place once a

pre-determined value of soil water was

depleted.

b.) Water budgeting

Estimates of vineyard water use and the

amount of water available in the soil profile

are needed when utilizing the water

budgeting method to determine when to

start irrigating the vineyard. Once the

irrigation season begins, this method can

be used to determine the intervals

between irrigations and the amount of

water to apply for flood or furrow irrigated

vines.

Example:

• Assume – a sandy loam soil in San Joaquin Valley

(Fresno area) with 1.2 m (4 ft.) rooting depth will contain

140 mm (1.38 in/foot) at field capacity while a clay loam

in Napa Valley (Oakville) will contain 190 mm (1.9

in/foot) at the same depth.

• Assume – trellis at both locations is a CA sprawl on an

11 foot row spacing and that the canopy developed

during the 2002 season.

• Allowable depletion is 50% (70 mm in the SJV and 85

mm in Napa Valley)

• Calculating ETc using 2002 reference ET data obtained

at each location the date of the first irrigation would

occur on May 19th near Fresno while that in Napa would

occur on June 19th.

Question:

Do vineyards on lighter soils require more

water once irrigations commence?

Answer:

ET of the vineyard is driven by evaporative

demand and canopy development. Assuming

that soil water is not limiting, ET of two vineyards

on different soil types will be the same as would

their irrigation requirements. If the water applied

to the lighter soil is lost below the rootzone, then

irrigation requirements will be greater. One

means to overcome this is to schedule irrigations

at a higher frequency with lowered amounts.

How to best monitor plant water

status and soil moisture:

Plant based techniques I’ve used:

• Pre-dawn leaf, midday stem and midday

leaf water potentials.

• Stomatal conductance and photosynthesis.

• Correlated above with soil water content

and soil matric potential

• Canopy temperature

• Crop Water Stress Index (CWSI)

• Remote sensing (UAV) to calculate CWSI

other stress indices

Plant based measurements of

water status should reflect the

amount of water available in the

soil profile (Higgs and Jones,

1990; Jones 1990).

Relationships among predawn (ΨPD), midday leaf

(Ψl), and midday stem (Ψstem) water potentials and

mean soil matric potential (Ψπ) of a Hanford fine

sandy loam.

• ΨPD = -0.059 + 0.94x

(R2 = 0.56 ***)

• Midday Ψl = -0.476 + 5.72x

(R2 = 0.88 ***)

• Midday Ψstem = -0.126 + 6.85x

(R2 = 0.83 ***)

• X in the above equations is soil matric potential

Thompson Seedless data

In general, most of the plant based techniques I’ve

used are highly correlated with one another and with

soil water content. I would use the one that is most

convenient and that a person feels most comfortable

with. I am of the opinion that any of methods (plant or

soil based) discussed could be used to determine

when to initiate irrigation early in the season. Once

the decision to irrigate has been made I would

calculate ETc using the product of ETo and Kc. I would

then irrigate at some fraction of ETc using sustained

deficit irrigation (SDI) or regulated deficit irrigation

(RDI). The fraction of ETc used to determine applied

water amounts would be based upon previous

experience in a particular vineyard and production

goals.

How do temperature spikes affect

vineyard ET and how best to mitigate

them?

The next slide contains data from

Napa Valley in 2002 during which I

was collecting data. It shows the

effect of rapid increases in maximum

ambient temperature on the

calculation of reference ET (ETo). Remember: ETc = ETo x Kc

Data from CIMIS station at

the Oakville research station

ETc = ETo x Kc

Reference ET was more

highly correlated with SR

during July than with max.

daily temperature.

75 F

105 F

Conclusions: • Mean maximum daily temperature for the month

was 29.2oC (~85oF). That recorded on July 9th

was 40.5oC (~105oF). Others in Napa Valley

recorded 113oF.

• Reference ET was ~ 30% greater on July 9th

compared to the mean monthly ETo.

• Would grapevine ETc also increase? It has been

shown in Australia that high temperatures

upregulate stomatal conductance of grapevines.

• Vapor pressure deficit (VPD) also increased

greatly during the heat spell.

• VPD has also been shown to decrease stomatal

conductance in a linear fashion.

How do temperature spikes

affect vineyard ET and how best

to mitigate them?

What else may be affected by

these temperature spikes?

Cabernet Sauvignon near Oakville: July 18th 2002

Desiccated berries of Cabernet Sauvignon grown in Lake County.

An attempt was made to quantify the

sunburn damage across most of the

treatments (trellis, rootstock, irrigation

amount and spacing)

• Only the 0.0 and 0.75 of estimated ETc irrigation treatments were examined.

• The total number of clusters per a four vine plot were counted. The four vine plots were replicated four times.

• A cluster was considered sunburned if it had a minimum of 5 sunburned berries.

• A cluster was considered desiccated if ~ 50% of the berries were dried.

• Data were collected on July 18, 2002.

1 x 1 m VSP Cabernet Sauvignon vineyard in Napa Valley.

Row direction was approximately east/west.

Row direction was approximately east/west.

Trellis and/or Irrigation % of total clusters

Row Spacing Rootstock Treatment w/sunburn desiccated

VSP 1 x 1 m 5C 0.0 97 70

0.75 94 46

110R 0.0 77 19

0.75 77 17

VSP 9 ft. row 5C 0.0 28 --

0.75 17 --

110R 0.0 8 --

0.75 7 --

Lyre 9 ft. row 5C 0.0 86 --

0.75 66 --

110R 0.0 43 --

0.75 19 --

The effect of trellis and/or row spacing, rootstock and applied

water amounts on the percentage of Cabernet Sauvignon clusters

w/sunburn. Row direction ~ east/west. LSD0.05 for w/sunburn

column = 12

Average effects of treatments

on clusters with sunburn • Trellis/training: VSP 1x1 m = 87; VSP 9 ft.

= 15; Lyre 9 ft. = 54

• Rootstock: 5C = 65; 110R = 38

• Irrigation: 0.0 = 57; 0.75 = 47

• There was a significant effect of rootstock

(LSD0.05 = 17) and irrigation amount

(LSD0.05 = 17) on desiccated clusters in

the 1x1 meter spacing.

Sunburn of grape berries:

• For grape berries to sunburn I am of the opinion several factors are necessary.

• Very high ambient or berry temperatures (> 40C [104F])

• Direct, prolonged exposure (> 2 - 3 hr.) to solar radiation

• Intermittent exposure of an individual berry to direct solar radiation will mitigate the degree of sunburn (California sprawl canopy will provide such protection)

Minimize sunburn/desiccation

• Provide good canopy coverage of the

fruit.

• While light can be beneficial to

enhancing fruit composition, minimize

fruit exposure during the hottest

portion of the day.

• Row direction and trellis type in

minimizing fruit exposure should be

considered

How to deal with the

possibility of losing

your water supply

before harvest.

Effects of cultivar and irrigation treatments

on yield of vines grown in the San

Joaquin Valley.

• Seventeen red, wine cultivars grown at the

KARE Center.

• All grafted onto 1103P.

• Irrigation treatments consisted of 1.) full

ETc from 1st irrigation to veraison and then

no applied water, 2.) applied water at 50%

of ETc season long and 3.) no applied

water to veraison and then applied water

at 50% of ETc up to harvest.

Cultivar Aglianico

Cabernet Sauvignon

Cinsault

Durif

Freisa

Grenache noir

Malbec

Montepulciano

Petit Verdot

Refosco

Sauzao

Syrah

Tannat

Tempranillo

Tinta Amarella

Tinta Madeira

Touriga Nacional

Red wine grape cultivars used in the study.

Applied water amounts as a % of full ET for the irrigation treatments across

years. (5.58 m2/vine = 1792 vine/ha = 725 vines/acre). A mean of 833 mm

of water is equivalent to 1230 gallons/vine. I Ni: full ET from 1st irrigation

of season to veraison, then no applied water. NI 0.5: no applied water to

veraison, then 50% ETc. 0.5 ETc: 50% season long.

---------------- Irrigation Treatment -----------------

Year I Ni 0.5 ETc NI 0.5 100% ETc Rainfall

(applied water amounts % full ET) (mm)(in.) (in.)

2012 49% 59% 39% 780 (30.7) 2.4/4.3

2013 54% 53% 29% 821 (32.3) 4.3/0.8

2014 62% 52% 28% 846 (33.3) 2.2/2.2

2015 42% 51% 36% 829 (32.6) 2.1/1.1

mean 52% 54% 33% 833 (32.7)

2016* 100% 54% 100% 891 (35.1) 9.3/2.0 *Treatments were irrigated at 100% ETc except for the 0.5 ETc treatment.

The effect of irrigation treatment on berry weight at

harvest across years. Values are the means of 17, red

wine grape cultivars grown at the Kearney Agricultural

Research and Extension Center.

----------------- Irrigation Treatment -----------------

Year I Ni 0.5 ETc NI 0.5 1.0 ETc

------------------- weight (g berry-1) ------------------

2012 1.44 (76%)* 1.52 (80%) 1.08 (57%) 1.89

2013 1.63 1.58 1.23 ---

2014 1.61 1.52 1.02 ---

2015 1.30 (72%) 1.59 (88%) 1.26 (70%) 1.81

mean 1.50 1.55 1.15 1.85

2016** 1.81 b 1.76 b 1.92 a

*Percent of 1.0 ETc treatment ** all treatments were irrigated at full ETc except the 0.5 ETc treatment.

The effect of irrigation treatment on soluble solids across years.

Values are the means of 17, red wine grape cultivars planted at

the Kearney Agricultural Research and Extension Center.

----------------- Irrigation Treatment -----------------

Year I Ni 0.5 ETc NI 0.5 1.0 ETc

-------------------- Soluble solids (Brix) -------------------

2012* 24.6 24.0 22.3 23.8

2013 24.5 24.1 24.0 ---

2014 24.6 23.8 22.9 ---

2015* 28.2 26.1 24.7 24.6

2016** 22.3 22.7 22.3 ---

*all treatments harvested on the same day ** all treatments were irrigated at full ET except the 0.5 ETc treatment.

The effect of irrigation treatment on yield across years. Values

are the means of 17, red wine grape cultivars planted at the

Kearney Agricultural Research and Extension Center. (5.58

m2/vine = 1792 vine/ha = 725 vines/acre).

----------------- Irrigation Treatment -----------------

Year I Ni 0.5 ETc NI 0.5 1.0 ETc

---------------------- Yield (kg vine-1) ---------------------

2012 11.7 11.9 7.2 14.3

2013 13.3 12.3 8.1 ---

2014 9.6 10.4 5.4 ---

2015 7.4 9.0 5.6 10.9

2016* 10.8 a 10.1 ab 9.9 b 12.2

t/acre** 33.2 34.7 21.0 ---

*Treatments were irrigated at 100% ETc except for the 0.5 ETc treatment. **Total yield across the first four years of the study as a function of irrigation treatment.

The effect of irrigation treatment on number of clusters per vine

across years. Values are the means of 17, red wine grape cultivars

planted at the Kearney Agricultural Research and Extension Center.

Treatments first applied in 2012.

----- Irrigation Treatment ------

Year I Ni 0.5 ETc NI 0.5

------------ Cluster #/vine ------------

2013 57 + 7 54 + 7 48 + 8

2014 49 + 8 45 + 7 38 + 5

2015 44 + 7 44 + 8 35 + 5

2016* 45.0 a 43.0 ab 40.6 b

I Ni = 100 ETc between berry set and veraison, no water after veraison Ni I = no water between berry set and veraison, 50% ETc after veraison 0.5 ETc = applied water at 50% of ETc all season. * all treatments were irrigated at 100% of ETc season long except the 0.5 ETc.

Conclusions • Early season stress (NI I) significantly reduced

berry size and yield across cultivars compared to the 0.5 ETc and late season (I ni) stress treatments. Early season stress also delayed the accumulation of sugar.

• Cluster number per vine was reduced in the NI I irrigation treatment compared to the other two trts.

• The I ni treatment had the greatest TA values in 2013 and highest total wine anthocyanins in 2014 compared to the two other treatments.

• The data would indicate that there are irrigation strategies to minimize reduction in yields of wine grapes due to limited water availability and possibly maximize fruit (wine) composition.

Potential vineyard

evapotranspiration (ET) due to

global warming: Comparison of

vineyard ET at three locations in

California differing in mean

seasonal temperatures

Background • An increase in global temperature has been

predicted to increase evaporative demand

as it is controlled by temperature, net

radiation, wind and relative humidity.

• Rainfall timing and amount may also

change to due an increase in temperature.

• An increase in temperature will accelerate

vegetative growth (canopy development).

• Such changes may result in an increased

demand for vineyard irrigation to minimize

yield reductions due to water stress.

Methods • Reference ET, temperature and degree-

day data were obtained (using 2009 data)

from three locations in California: the

Carneros district at the southern end of

Napa Valley, Lodi located in the northern

San Joaquin Valley and Parlier (Fresno)

located in the southern San Joaquin Valley.

• Carneros: 38o 13’ N/122o 21’ W (2 m elev.)

• Lodi: 38o 8’ N/121o 23’ W (8 m elev.)

• Parlier: 36o 36’ N/119o 21’ W (103 m elev.)

Lodi

Parlier

Carneros

Map of California

North

Pacific

Ocean

Methods • It was assumed that the same cultivar and

rootstock was used at all locations.

• It was assumed that the trellis/canopy type

was a California sprawl and that the

vineyards had row spacings of 3.35 m (11 ft.).

• The seasonal Kc was a function of degree

days (> 10 C) using temperature data

recorded at CIMIS weather stations from

each location (obtained from the UC IPM website and

calculated using the single sine method). The seasonal

maximum Kc was 0.82 at all locations.

Typical California sprawl type canopy

3.05 m (10 ft.) between rows in this vineyard

Monthly mean high temperature at three

locations in California during the 2009

growing season

--------------- Temperature (oC) --------------

Month Parlier Lodi Carneros

March 19.8 18.5 18.1

April 23.6 22.6 20.6

May 30.7 27.7 22.8

June 30.7 28.2 24.8

July 36.9 31.3 26.5

August 34.8 31.4 27.8

September 33.5 31.7 28.9

October 23.5 22.9 22.5

Mean 29.2 26.8 24.0

Cumulative DDs from March 15 to October 31. Cumulative DDs at Carneros and Lodi are 59 and 80%, respectively, those at Parlier (To convert from degree days in C to F, multiply by 1.8.)

2835 (II)

3864 (IV)

4806 (V)

DDs

Base 50 F

Cumulative ETo from March 15 to October 31. ETo values at Carneros and Lodi are 84 and 95% that at Parlier.

44.7 in.

42.5 in.

37.6 in.

Cumulative estimated vineyard ET from March 15 to October 31. ETc values at Carneros and Lodi are 77 and 94%, respectively, that at Parlier.

Conclusions

• Mean monthly temperature at Parlier was 5.4

and 2.4 C greater than those at Carneros and

Lodi, respectively across the growing season.

• However, mean monthly solar radiation at

Parlier was only 10 and < 1% greater than

those at Carneros and Lodi, respectively.

• Thus the differences in ETo across locations

were less than one may assume based solely

upon temperature data. Seasonal ETo at

Carneros and Lodi were 84 and 95% that at

Parlier, respectively.

Conclusions • Estimated vineyard ET at Parlier was 39 and 6% greater

than those at Carneros and Lodi, respectively.

• The greater ET at Parlier compared to the other locations

was due in part to a more rapid canopy development in

response to increased temperature (affecting the seasonal

crop coefficient).

• Based upon the data presented in this talk, an increase in

seasonal temperature in a viticultural region more than

likely will increase vineyard water demand.

• This does not take into account a continued increase in

CO2 concentration and/or decreases in VPD. Such an

increase may decrease vineyard water use due to a

reduction in stomatal conductance which may mitigate

increases in evaporative demand as demonstrated by

recent research.

Conclusions • Estimated vineyard irrigation requirements due to

global warming will depend upon several other

factors to include: rooting depth and soil type and

viticultural practices such as row spacing, trellis

used and grape type (raisin, table or wine grapes).

• The seasonal pattern of rainfall and its amount will

also affect irrigation requirements.

• The absolute difference in grape growing regions

presented here did not take into account date of

harvest. If harvest date in delayed in the cooler

growing region then ETc from budbreak to harvest

(and not until the end of October) may be more

similar across regions than presented here.

Things you can do to assist in

irrigation management. • Get an estimate of ET for your vineyard(s).

• Collect degree days from budbreak each year and

determine DDs as a function of phenological

events.

• Download ETo data from closest CIMIS station (or

other means).

• Download rainfall amounts/events.

• Measure applied water amounts and record as a

function of time (DDs).

• Using the above develop an irrigation coefficient.