California walnut acreage trending upward - Diamond Foods

SUMMER 2008

IN THE NEWS: 2008 crop…3 Surround® study…4 Marketing & sales report…6 Irrigation efficiency…8

California walnut acreage
trending upward

The importance of expanding new and existing sales channels
with innovative products has never been greater

In late May, the California Agricultural Statistics than 50% of the total industry tonnage.
Service (CASS) released its 2007 walnut acreage Geographically speaking, nearly 45% of total
report showing California’s total acreage at 243,000 walnut acreage is in the Sacramento Valley, while ap-
acres (218,000 bearing acres and 25,000 nonbearing). proximately 40% is in the San Joaquin Valley. The
The 2007 survey results indicate bearing acreage has Sacramento Valley is the most rapidly expanding wal-
increased by 9% since 2000. The positive economic nut growing region in the state with Butte, Sutter and
benefits of walnut production continue to drive in- Tehama counties accounting for the highest number of
creased plantings, replacing many other fruit and nonbearing acres. Areas in the San Joaquin Valley with
field crops. the highest growth rates include San Joaquin County at
Based on the acreage reported to CASS, the 31,490 acres and Tulare County with 22,549 acres.
Chandler variety continues to lead the industry with Since 2000, net bearing acreage has increased by
71,631 total acres, followed by Hartley at 41,626 acres, 2,571 acres each year. Based on this rate of growth, the
and Serr with 17,873 acres. Rounding out the top six industry is on track to realize significant increases in
varieties are Howard (17,409 acres), Vina (14,734 future production. Assuming that the average orchard
acres) and Tulare (14,309 acres). In 2007 these major has a life of 35 years, 6,229 acres (218,000 acres/35
varieties represented over 73% of the state’s total acre- years) are removed annually. Just to maintain the acre-
age and greater than 85% of statewide production. age base, 6,229 acres must be replanted annually. Since
Chandler continues to be the most heavily plant- the industry has exhibited a net annual growth rate of
ed variety at nearly three times the combined annual 2,571 acres, 8,800 acres are actually planted each year.
planted acreage of Howard and Tulare, the second The yield per acre of the removed orchards typically
and third most popular new varieties. Chandler’s pro- averages 1,500 lbs/ac, resulting in the removal of ap-
pensity for producing high quality and excellent yields proximately 9.3 million pounds of production each
continues to make it an ideal cultural fit in nearly all year by the industry. Production from new plantings
growing areas across the state. The Howard and Tulare of high density/high yielding varieties more than off-
varieties, in contrast, are more regionalized with high- sets the yearly loss due to orchard removal. In fact, the
er plantings of Howard in the Sacramento Valley and 8,800 acres that come into production each year will
significantly more Tulare planted in the San Joaquin typically average more than 5,000 lbs per acre when
Valley. Climate, soil type and performance, as well as full production is obtained, resulting in the potential of
leafing and harvest dates have all contributed to the an additional 44 million lbs of walnuts annually. Thus,
regional differences. While the industry should con- the net increase that the industry may experience on
tinue to see increased overall tonnage of Chandler, an annual basis is 34–35 million lbs.
nearly 25% of the Howard and Tulare acreage is still Given the magnitude of growth brought about by
nonbearing, which will result in escalating production additional plantings of higher yielding varieties, the
from these two varieties in the near future. In 2007, importance of expanding new and existing sales chan-
these three premium varieties alone produced more nels with innovative products has never been greater.

Walnut marketing Early Harvest
update Program
reminder
While the overall supply of tons, the overall supply of 363,679 tons
364,000 tons in 2007 was was approximately 47,000 tons less than Even though walnut harvest
13% lower than the supply the previous year’s total supply and the is still several months away,
in 2006, the industry’s year-to-date lowest total supply since the 2001/02 it’s not too early to review
shipments through May 2008 have marketing year. Diamond’s Early Harvest Program
continued at a pace that is only 5% off The strength of overseas currency and begin developing an optimal
of last year’s for the same period. against the U.S. dollar continues to make harvest timing strategy.
Shipments for the month of May, U.S. walnut products more affordable Like 2007, the 2008 Early Harvest
however, started to display the impact in key export markets. For example, the Program will not have any predeter-
of a tightening supply, resulting in an purchasing power of the Euro is 16% mined cutoff dates, but rather will
18% reduction in shelled shipments stronger than the dollar compared to a pay a bonus of 1–3 cents/lb based
for the month compared to May 2007. year ago and 50% stronger than 10 years on each delivery’s timing relative
This reduction in shipments was ago. While these favorable exchange to the timing of the total pounds of
anticipated, given the total available rates produce short-term opportunities, each individual variety Diamond
supply for the 2007/08 marketing year Diamond continues to develop value- receives. Eligible varieties include:
was less than the total shipments for added products for less price-sensitive Ashley, Payne, Vina, Hartley, Serr,
the prior year. markets which will generate good mar- Tulare, Howard and Chandler. More
Based on the 2007 crop of 323,083 gins regardless of currency fluctuations. detailed information will follow in the
tons and a carry-in inventory of 40,596 2008 Harvest issue of the Diamond
Grower News, which will be mailed
Industry Shipment Reports to you in August, or feel free to con-
tact your local field representative.
Through May 31, 2008 For those who may be consider-
ing the use of harvest aids such as
INSHELL (1,000 POUNDS) Ethrel® to advance your harvest,

2006/07 Marketing Year 2007/08 Marketing Year Factors to consider when
using a harvest aid:
Domestic May 2007 Aug. 1, 2006– May 2008 Aug. 1, 2007–
Export May 31, 2007 May 31, 2008 • General orchard health
73 123 • Tree stress
Total 1,232 22,703 2,222 20,150 • Insect pressure
100,070 • Harvester and dehydrator
98,067 availability
• Ambient temperatures
1,305 122,773 2,346 118,217 and other environmental
conditions at the
SHELLED (1,000 POUNDS) proposed application time
• Application timing*
2006/07 Marketing Year 2007/08 Marketing Year
* A note on application timing—A
Domestic May 2007 Aug. 1, 2006– May 2008 Aug. 1, 2007– harvest aid applied too early in the
Export May 31, 2007 May 31, 2008 growing season or before optimal
12,037 10,343 receptivity can actually decrease
Total 7,442 139,611 5,723 133,596 your quality.
85,030
80,244

19,480 224,641 16,066 213,840

INSHELL EQUIVALENT TONNAGE*

2006/07 Marketing Year 2007/08 Marketing Year

Domestic May 2007 Aug. 1, 2006– May 2008 Aug. 1, 2007–
Export May 31, 2007 May 31, 2008
14,132 12,144
9,330 174,830 7,797 166,145
149,602
142,777

Total 23,462 324,432 19,941 308,922

*2006/07 shellout rate 42.7 — 2007/08 shellout rate 42.8

Source: California Walnut Board

2 GROWER NEWS

Start planning 2008 crop off to good start
now—harvest isn’t
The 2008 walnut crop got off to a very optimistic start, with the initial crop set
that far off! looking to be significantly improved over 2007 on many of the major varieties.
The winter chilling accumulation was substantially improved over the prior
please consult with your agricultur- year in all growing regions, allowing trees to leaf out much more uniformly, and
al consultant for details on optimal conditions were generally dry during bloom. The dry weather also minimized blight
timing and application rates for levels and allowed growers to stretch the interval between sprays.
your specific orchards and variet- As the bloom and early growing season progressed, the weather turned cold
ies (see box for factors to take into during the week of April 20 and threatened various growing regions with the poten-
consideration). tial of frost damage. The frost materialized very quickly, with nighttime tempera-
tures plummeting as much as 7 degrees in a matter of minutes. The sudden cold,
Irrigation management is a coupled with exceptionally low humidity, resulted in what is termed a “black frost”
key factor in a complete program that caused hit-and-miss damage across the north state. Temperatures dropped as
aimed at optimizing your harvest low as 25°F for several hours and the frost injury could be seen in the tops of the
and crop quality. This spring has trees, rather than at ground level, which is a more typical pattern. As a result, the
been exceptionally dry and we young, sensitive leaf tissue that was emerging on mid- and later-season varieties suf-
have already experienced unsea- fered some damage.
sonably warm temperatures, so While the damage was neither widespread nor uniformly distributed, it was
monitor your trees for stress and ap- more prevalent in the northern Sacramento Valley and North Coast areas than in
ply enough water ahead of time other parts of the state. Much less damage has been seen in the major growing areas
to keep the trees adequately hy- of the San Joaquin Valley. The damage to orchards in the Sacramento Valley was
drated in preparation for more high inconsistent, with some trees affected and other parts of the same orchard virtu-
summer temperatures. Minimizing ally unharmed. Frost control measures, orchard topography, soil moisture levels,
tree stress through good irrigation orchard floor vegetation and many other factors all influenced the various levels of
management practices can posi- injury. Younger orchards (0–5 years of age) may have been injured more than ma-
tively influence your crop quality ture orchards due to the stage of growth and possibly because of the lack of a more
and increase your crop return (for dense tree canopy, which may have held in more radiant heat and allowed mature
more information, see article on trees to fare better.
page 8). In spite of frost injury to some orchards, the crop as a whole continues to de-
velop well and generally on time, with many growers still commenting on the heavy
nut set on many varieties. The Vina, Tulare and Chandler varieties have greatly
increased their nut set over 2007. Varieties like Ashley, Serr and Howard, which had
very heavy crop loads in 2007, appear to have come back with another solid crop,
while Hartley and other varieties like Tehama and Chico also have improved.
Based on the improved crop set on many of the major varieties and combined
with the influx of additional new acres, the 2008 crop is likely on track to set a new
record.

Dan Newman is our new
Grower Services manager

Diamond is pleased to an- sales and product develop-
nounce the appointment ment experience from his prior
of Dan Newman as Grower work in various agricultural
Services manager for the industries. He will also man-
Sacramento Valley and North age Diamond’s Live Oak Plant
Coast growing areas (Locals and other receiving operations
11, 24 and 27). Newman is across the northern growing
a native of Woodland and region. Reach him by phone
brings with him a tremendous at (530) 218-2612 or email at
amount of customer service, [email protected].

GROWER NEWS 3

Use of Surround® WP
crop protectant on walnuts

By Kathy Kelley Anderson, UCCE Farm Advisor, Stanislaus County
Dr. Bruce Lampinen, UCCE Walnut and Almond Specialist, UC Davis

With high prices and a good Research has shown that increased in any of the years. The mate-
crop on the trees, walnut Surround can improve rial and application costs of multiple full-
growers are interested in quality and crop value canopy sprays, however, can exceed the
maintaining nut quality to ensure the increase in crop value when calculated
highest return. Sunburn and heat stress peratures, of course, never get this high, on a 60 cents-per-pound basis. Feasibil-
negatively impact quality, but growers but surprisingly, exposed walnuts were ity improves with increasing nut prices.
have traditionally regarded these as un- found to be up to 20°F warmer than the In an effort to reduce costs, half-canopy
manageable factors. Research has shown surrounding air. sprays, applied to the south or west sides
Studies over a four-year period in of the tree rows were evaluated. Results
that Surround® can improve quality and Stanislaus County compared untreated showed that Surround sprays applied
and Surround-treated nuts in well- only to the side of the canopy receiving
crop value. managed Vina, Howard, Tulare, and afternoon sun were effective (Table 2).
Surround is a naturally occur- Chandler orchards. The quality of har- For optimum protection, thor-
ring clay mineral, kaolin, used in many vested nuts was evaluated by Diamond ough, uniform and complete coverage
consumer products including toothpaste Foods, Inc. and showed that Surround is required for best results. Label rates
and cosmetics. Kaolin is mined from improved the percentage of large sound, for ground applications currently range
the earth and processed into superfine external damage, mold, offgrade and from 25–75 lbs per acre in 100–200 gal-
particles. When mixed with water and edible yield and increased relative value lons of water. In varying the amount of
sprayed on walnut trees, the particles (Table1). material and water, do not go under the
link together to form a protective white Results varied among varieties and effective dilution rate of 1 lb of Surround
film that reflects the sun’s heating infra- years. Quality and value increases were in 2–4 gallons of water. Spray trees to
red wavelengths as well as the burning seen consistently in Vina. Improvements wet. Three applications of Surround at
ultraviolet rays, resulting in cooler trees with Howard and Tulare were more 50 lbs per 200 gallons of water per acre
and less sunburn. USDA apple research- variable while Chandler value was not gave good results in Stanislaus County
ers found that the material does not trials. Improve coverage by changing the
block the stomates and, in fact, increases Photo by Bruce Lampinen direction of travel on alternate applica-
photosynthesis. The material has also tions. For example, if you start in the first
been shown to suppress codling moth Tiny temperature sensors were taped on row and move east on the first applica-
and walnut husk fly and is OMRI ap- treated and untreated leaves and nuts and tion, alternate directions and start on the
proved for use in organic production. temperatures were continuously recorded over west side of the first row for the second
Research conducted by Dr. Bruce a several-day period in midsummer. application.
Lampinen showed that Surround was ef- The label says to make the initial
fective in lowering leaf and nut tempera- application before a forecasted damaging
tures and preventing sunburn damage heat event. The trials indicated that in
in walnuts. Tiny temperature sensors, most years in the Central Valley, timing
called thermocouples, were taped on the initial application in early to mid-
untreated and Surround-sprayed sun- June works well. One application will not
exposed leaves and nuts and tempera- provide sufficient protection. Reapply
tures were continuously recorded over a Surround as needed to maintain suffi-
several day period in midsummer (see cient coating during hot weather. In trial
photo). Results indicated that exposed work, the intervals were determined by
Surround-treated walnuts were 4–8°F the degree of material weathering and
cooler than untreated nuts, enough to high temperature forecasts. The second
keep them below the estimated sunburn
damage threshold of around 122°F. Tem-

4 GROWER NEWS

application was typically made within efficacy. On tall trees with exposed nuts Photo by Bruce Lampinen
10 days to three weeks depending on only on the top of the canopy, three
conditions. Spray intervals between the aerial applications at the rate of 30 lbs in
second and third application ranged 20 gallons of water per acre have given
from three to four weeks. The total num- good results in non-trial situations. The
ber of applications was limited to three label recommends aerial applications at
per season, which in some years resulted the rate of 25–35 lbs of Surround WP in
in poorer coverage in mid-to-late August 25–35 gallons of water per acre.
when damaging temperatures occurred. A real benefit of Surround is that
The label recommends repeating ap- you can use it to evaluate spray coverage
plications on a 21-day schedule, which by assessing the evenness of the white
ensures good coverage through August. coating on the trees. As with all materi-
With larger trees, experience shows that als, apply at label rates and consider a
shutting off lower nozzles and directing tankload of Surround in your next round
the spray to the upper canopy improves of spraying.

Table 1. The effect of full-canopy Surround treatments on nut
quality and relative value of Vina, Howard and Tulare (2004)

Treatment % % Large % External % Relative
Large Sound Damage Mold Value

Vina Surround 0.99** 0.95* 0.01 ns 0.00 ns 0.87*
Untreated 0.97 0.93 0.01 ns 0.01 ns 0.85

Howard Surround 1.00** 0.91* 0.00** 0.00** 0.91** Photo by Kathy Kelley Anderson
Untreated 0.91 0.88 0.01 0.02 0.85
Thorough, complete coverage is required for
Tulare Surround 1.00** 0.90 ns 0.00** 0.00** 0.96 ns best results. Photo at top shows the effect of
Untreated 0.96 0.90 ns 0.01 0.01 0.94 ns incomplete coverage; photo above shows
good coverage obtained by three applications
Students Paired t Test **P ≤ .05 *P≤ .10 ns=no significant difference of Surround at 50 lbs per 200 gallons of water
per acre.

Table 2. The effect of full and half-canopy Surround treatments on nut quality and
relative value of Vina, Howard and Tulare walnuts (2005)

% Large % External % Mold % Offgrade % Edible RLI Relative
Sound Damage Yield Value

Vina Full 82.1 a Full 0.8 a Full 0.0 a Full 1.0 b Full 48.4 a Full 47.6 ns Full 0.84 a
Half 1.0 a Half 0.0 a Half 1.3 b Half 47.8 a Half 47.8 ns Half 0.83 a
Orchard 1 Half 82.8 a None 2.4 b None 0.5 b None 2.8 a None 46.1 b None 47.9 ns None 0.80 b

None 64.4 b

Vina Full 94.6 a Full 1.3 b Full 1.0 ns Full 2.4 c Full 48.8 a Full 47.7 ns Full 0.85 a
Orchard 2 Half 87.6 b Half 1.5 b Half 1.3 ns Half 3.9 b Half 48.3 a Half 48.2 ns Half 0.85 a
None 84.6 b None 5.8 a None 3.3 ns None 7.0 a None 45.5 b None 48.1 ns None 0.80 b

Howard Full 91.6 ab Full 1.9 ns Full 2.9 ns Full 6.0 ns Full 47.2 ab Full 50.0 ns Full 0.86 ab
Half 94.4 a Half 1.9 ns Half 1.1 ns Half 4.3 ns Half 49.4 a Half 49.8 ns Half 0.90 a
None 88.9 b None 3.0 ns None 2.0 ns None 6.7 ns None 46.5 b None 50.2 ns None 0.85 b

Tulare Full 95.1 a Full 1.5 b Full 1.3 b Full 3.3 ns Full 51.7 a Full 50.7 ns Full 0.94 ns
Half 95.2 a Half 1.4 b Half 0.8 b Half 3.7 ns Half 50.7 ab Half 50.7 ns Half 0.94 ns
None 90.0 b None 7.4 a None 2.7 a None 6.0 ns None 49.5 b None 50.6 ns None 0.91 ns

Mean values followed by the same letter are not significantly different Duncan’s Multiple Range test for mean separation (P < 0.05)
ns = No significant difference

GROWER NEWS 5

MARKETING &

Harvest Reserve line touted
for flavor, nutrition
Retailers were giv-
en plenty of excel- Chandler variety) as well as Walnut Halves are full of anti- cellent source of Vitamin E
lent reasons recently Harvest Reserve Pecan Halves oxidants, including Omega 3; (1 serving equals 35% of the
to increase their orders for and Harvest Reserve Whole just one serving a day may in- daily requirement), while
Diamond’s premium culinary Almonds. Only the finest of crease HDL (“good”) choles- Harvest Reserve Pecan Halves
line. The line features three each type of nut makes it into terol, decreasing risk of stroke are loaded with fiber, calci-
different nut types: Harvest the standup reclosable Harvest and heart disease, accord- um, potassium, iron and oleic
Reserve Walnut Halves Reserve bag. ing to the American Journal acid, a monounsaturated fatty
(85% halves, all light-color They also were remind- of Clinical Nutrition. Harvest acid believed to reduce “bad”
ed of the nuts’ nutritious at- Reserve Almonds are an ex- (LDL) cholesterol.
tributes: Harvest Reserve

Rave reviews!

One of Diamond’s newest prod- “Innovation is critical to expanding the nut
ucts, Emerald Cocoa Roast Dark category. Consumers who have a craving
Chocolate Almonds, is already earning for something sweet in the past would not
raves from the media. These crunchy, have been able to satisfy that within snack
nuts,” explained Andrew Burke, Diamond’s
flavorful nuts offer the taste of choco- senior vice president of marketing.
late without the added calories and Here’s just a sampling of the kudos:
fat found in chocolate-dipped nuts. • Men’s Health magazine, with a cir-
The online and print praise is outlined culation of over 1.8 million, selected the
product as “Best Flavored Nuts” in its “Best
in a sheet the sales force and brokers of the Snack Aisle” roundup.
give to retailers. • iVillage.com, the No. 1 online destina-
Because the flavor is roasted into tion for women with 31.4 million unique
the nuts, the nuts are shelf-stable
and don’t require refrigeration.

6 GROWER NEWS

SALES REPORT

Rushed for breakfast?
Grab it ‘on the Go’

First trail mix product featuring glazed
Diamond walnuts

No time in the morning for a healthy breakfast? If you’re like lots of
consumers, you’ll be in luck when Emerald Breakfast on the Go
comes to a supermarket shelf near you.
Breakfast on the Go is a new multi-pack of delicious, nutritious Emerald
Breakfast Blend and Berry Blend Trail
mixes. Each box contains six, 2.25 oz
bags of nuts and dried fruit—natural en-
ergy for the busy on-the-go person. They
also are the first product of this type
to feature Diamond’s patented process
glazed walnuts. In fact, Emerald-brand
trail mixes are the only trail mixes on the
market that include healthy and nutri-
tious walnuts.
The product will launch in July in
3,000 Wal-Mart stores.

‘The most delicious thing ever’ AS SEEN IN:
—Teenvogue.com, 6 million hits/month
GROWER NEWS 7
visitors a month, stated: “These nuts are • Upcoming issues of the popular
a great alternative for people who are health magazines SELF and Shape will
addicted to M&M’s or any chocolate recognize Emerald Cocoa Roast Al-
with nuts.” monds as a great snack option. The cir-
• Parenting.com, a website with aver- culations of these magazines are nearly
age page views of over 4.7 million, in- 1.5 and 1.75 million, respectively.
cluded Emerald Cocoa Roast Almonds • Reaching out to the teen market,
as a “Daily Fave.” Cosmogirl.com (9 million hits per month)
• Womansday.com (over 1.2 million raved “they are awesome! …I highly
unique visitors per month) declared Em- recommend you taste them!” And the
erald Cocoa Roast Almonds as one of its headline on Teenvogue.com (6 million
“best summer snack foods.” hits per month) said it all: “The most deli-
cious thing ever.”

Walnut water use and
irrigation management

By Terry Prichard, UCCE Water Management Specialist
Joe Grant, UCCE Farm Advisor, San Joaquin County

Irrigation is the single most important ac- by a land coverage factor, or crop coefficient
tivity in walnut production in the Sacra- (Kc) specific to walnut orchards. The product
mento and San Joaquin valleys. Orchard equals the orchard water use:
water use can exceed 42 inches per year
without a cover crop. The use of a cover ETo x Kc = ETc
crop can add up to 20% more seasonal
water use. Inadequate irrigation can lead Crop coefficients for mature walnut or-
to poor tree vigor, deep bark canker and chards have been experimentally determined
reduced yield and crop quality. Too much for various times through the growing season.
irrigation can also be detrimental, increas- An orchard is considered to be mature when
ing the risk of root diseases and associated about 60% or more of the orchard floor is
yield and quality reductions. Therefore, the shaded at midday. Table 1 shows the calcula-
appropriate timing and amount of irriga- tions for determining walnut orchard water
tion water are keys to maximizing tree health and crop quality. use, in two-week periods, from leaf-out to
Water use begins at a low level as trees leaf out in spring leaf drop using CIMIS station No. 70 located
when climatic conditions are mild; it increases as the canopy near Manteca. Historical ETo daily and summed values are
develops and the climatic demand increases to its maximum available for the Manteca and Lodi (No. 166) CIMIS stations
in the July–August time period. Water use declines after this based on the past 20 years of data at http://cesanjoaquin.ucda-
period to leaf drop. vis.edu/Custom_Program/Publications_Available_for_Down-
The orchard uses soil-stored winter water, in-season effective load.htm
rainfall, and irrigation water to meet its requirement for water. If rainfall occurs that increases the soil-water content
(called effective rainfall) during these periods, the amount must
Scheduling irrigations be subtracted from the ETc, effectively reducing the irrigation
The best way to determine the irrigation requirement is by requirement. Most feel that for rainfall to be effective it must
using climatic data and a specific orchard’s characteristics to occur in a quantity that exceeds the daily ETo by a factor of
estimate the volume of water consumed by the orchard. This is three. As an example, a rainstorm on April 25 would have to be
called the evapotranspiration of the crop or Etc: 0.6 inch to exceed the 0.2-inch ETo average for that date. The
Irrigation requirement = ETc – effective rainfall method used to approximate the effective in-season rainfall is:

+ irrigation system losses (0.6 rainfall -.25) / 0.8 = 0.28 inch effective rainfall

ETc in inches of water can be time-framed to the day, week, Soil storage plays an important role in the seasonal ir-
month or season in order to asses the orchard’s water require- rigation requirement; however, its importance in scheduling
ments for irrigation scheduling purposes. Typical historical (or diminishes as midsummer is reached. By this time, a substantial
average year) ETc for walnuts in the Stockton area is 7.2 inches portion of the soil-stored water has been consumed, allowing
for the month of August. scheduling to occur based on ETc alone. Early-season schedul-
ing, using stored soil moisture as a component is possible, but
beyond the scope of this article.

Calculating orchard water use (ETc) Determining the irrigation amount
Data from a network of nearly 100 California weather stations Once the orchard water requirement has been determined, the
are available for calculating daily reference evapotranspira- irrigator must account for losses such as evaporation, runoff
tion values—called ETo—from which walnut ETc estimates or deep percolation. These losses depend on both the irriga-
can be derived. This information is made available to grow- tion system type and management. Surface irrigation (border
ers by the CIMIS program in the California Department of check and furrow) can have substantial runoff losses and has
Water Resources at http://wwwcimis.water.ca.gov/cimis. Some larger variability in infiltration than pressurized systems. This
newspapers and irrigation districts also provide ETo data. The variability in infiltration requires the application of additional
daily ETo data are summed into weekly ETo, then multiplied water to achieve a minimum amount of water to all parts of the

8 GROWER NEWS

Table 1. Irrigation scheduling using ETo lons per minute can be divided acreage covered, then converted
values based on a 20-year average to depth of water per unit land area:

Manteca, CIMIS Station 70. Leaf out: 3/15 Leaf drop: 11/15 1811 GPM flow / 40 acres = 45.3 GPM/acre /
No cover crop 27154 gal/ ac inch * 60 min/hr = 0.10 inches per hour

Date Evapotranspiration Crop Water Use Cumulative System run time is then calculated from the irrigation
Reference Coefficient (inches) Inches requirement and application rate:

ETo KC ETc ETc 4.8 inch irrigation requirement /
0.10 inch /hr application rate = 48 hrs
Mar 16-31 2.3 0.12 0.28 0.3
Irrigating young trees
Apr 1-15 2.5 0.53 1.34 1.6 Young trees (those with less than 60% shaded orchard floor
measured at midday) are generally better irrigated using soil-
Apr 16-30 2.9 0.68 1.96 3.6 based monitoring. Monitoring soil moisture can often be more
critical in young trees than a mature orchard due to the greater
May 1-15 3.3 0.79 2.59 6.2 potential for excessive soil water saturation leading to root
disorders.
May 16-31 3.6 0.86 3.14 9.3
Verify calculations and applications
Jun 1-15 3.8 0.93 3.53 12.8 The climate-based method described above for assessing
orchard water demand use gives an estimate of demand that
Jun 16-30 4.0 1.00 3.98 16.8 should be verified and fine-tuned by soil- or plant-based moni-
toring of actual orchard water status. If soil water decreases
Jul 1-15 4.1 1.14 4.66 21.5 over the season or soil water tension increases past safe levels,
too little irrigation was applied. If soil water content increases
Jul 16-31 3.9 1.14 4.49 26.0 or tension is reduced each irrigation, too much irrigation is
indicated.
Aug 1-15 3.7 1.14 4.16 30.1 In plant-based monitoring, midday stem water potential
(SWP) is measured to assess plant water status. A pressure
Aug 16-31 3.5 1.14 3.98 34.1 chamber is used to measure bagged leaves for plant water status
(see http://fruitsandnuts.ucdavis.edu/crops/Almond_Midday-
Sep 1-15 2.9 1.08 3.12 37.2 StemWaterPotential.pdf ).
Ideally, pressure chamber measurements should be made
Sep 16-30 2.4 0.97 2.30 39.5 between 1 and 3 p.m. for the best consistency. If necessary, the
1P.7ho3to by Bruce L4am1.p3inen sampling time can be stretched to between noon and 4 p.m.
Oct 1-15 2.0 0.88 to accommodate coverage of larger acreages. The foil bag used
in pressure chamber measurements needs to cover the leaf for
Oct 16-31 1.6 0.51 0.79 42.1 only 10 minutes before removing the leaf from the tree and
placing it, still inside the bag, in the chamber. Make measure-
Nov 1-15 1.1 0.28 0.30 42.4 ments within a few minutes after cutting a leaf from the tree,
because stem water potential drops rapidly after the leaf has
orchard. Sprinkler irrigation systems have greater application been excised from the tree. Collecting more than one leaf at a
uniformity, less deep percolative losses and little if any runoff time is not recommended.
when compared to surface systems. Drip and micro-sprinkler Sample leaves from at least five trees per orchard block,
systems have the advantages of sprinkler systems and addition- although the actual number may depend upon the variability
ally have less evaporative losses. To account for these differenc- among soils, tree age, tree health, and other growing condi-
es between systems, we use the term “irrigation efficiency” to tions. Select trees to sample that are representative of the
adjust the applied irrigation water amount to meet the orchard entire orchard. If the orchard has drier and/or wetter areas, it
water requirement. is important to sample trees in these areas as well as those in
Note: significant variability occurs within system type due more “average” areas. Return to the same trees for repeated
to the range of conditions in each system type. Use this as a measurement during the season. In walnut, select a terminal
generalized guide. As an example for sprinkler irrigation: (end) leaflet from the compound leaf. The terminal leaflet will
have the longest stem and is easier to work with in the pres-
3.6 inch orchard requirement / sure chamber. Choose the leaf from among shaded leaves in
the lower canopy near a scaffold branch or the trunk and cover
0.75 = 4.8 inch irrigation requirement it with a foil bag for at least 10 minutes. Weekly sampling is

System Type Estimated “Typical” Efficiency
Surface Irrigation 0.60
Sprinkler 0.75
Micro Sprinkler 0.85
Drip 0.90

Determine irrigation on-time
The average irrigation system application rate is determined by
simply dividing the amount of water applied per unit time by
the land area it is applied to. For example, pump volume in gal-

GROWER NEWS 9

suggested but less frequent measurement may still be valuable. ing SWP on overcast and unusually cool days or extremely hot
Measurements within a few days after irrigation and just before and windy afternoons. For the advanced pressure chamber and
the next irrigation are most informative because they represent SWP user, predictive models have been developed for walnuts,
the wettest and driest conditions present over the irrigation almonds and dried plums to estimate the SWP level that would
cycle. For an experienced pressure chamber operator, it should be expected for specific air temperatures and relative humidity
take about 30–45 minutes per orchard block to complete about conditions. Separate tables for predicting SWP for fully irri-
10 measurements. gated walnuts, almonds and dried plums are available.
By using representative sources of mid-afternoon air
Interpreting measurements temperature and relative humidity for your location (i.e. CIMIS
Refer to the table of “Tentative Guidelines” for walnuts (below). weather station, FieldWise Inc. weather, or NOAA), these tables
These guidelines are preliminary and will be updated as ongo- can be used to predict SWP levels that could be expected when
ing research and development is completed. However, these the orchard is fully irrigated (soil moisture is not limiting).
guidelines are believed to be reasonable to assist new users with Comparing the prediction for fully irrigated conditions to the
the pressure chamber and midday stem water potential. They field measurement helps clarify the orchard water status and
were based on two research trials conducted in Tehama and San extent of crop stress.
Joaquin counties.
What’s happening this year?
Baseline estimate of SWP for fully irrigated orchards This year (beginning at leaf-out) started with less than a full
Since SWP is a plant-based indicator of orchard water status moisture profile, primarily due to lack of rain close to leaf-out
and integrates root health, soil moisture and weather condi- and use by orchard floor vegetation. The continued lack of
tions into each measurement, it is possible to measure differ- spring rain combined with tree and vegetation water use further
ent levels (commonly –1 to –2 bars difference) of SWP on the depleted the soil profile of stored moisture. Irrigation should
same tree and under the similar soil moisture conditions when have begun earlier than normal to account for this moisture
the weather conditions at the time of measurement are differ- deficit. Measurements of soil moisture show that with the lack
ent. The novice user of the pressure chamber needs to be aware of upper profile moisture, deeper moisture is being depleted
of the influence of weather at the time of measurement. The at a rapid rate. It is essential that growers calculate irrigation
simplest way to minimize this variable is to measure SWP on requirements and apply water so as to preserve deep moisture
clear days with near-normal temperatures and avoid measur- for use during the peak demand periods of July and August.

Table 2. Tentative guidelines for interpreting pressure chamber readings

(Midday Stem Water Potential–SWP) in Walnut

Pressure Chamber Reading Crop: Walnut
(– bars) Not commonly observed.
0 to –2.0 Fully irrigated, low stress—commonly observed when orchards are irrigated according
–2.0 to –4.0 to estimates of real-time evapotranspiration (ETc), long-term root and tree health may
be a concern.
–4.0 to –6.0 Low to mild stress—high rate of shoot growth visible, suggested level from leaf-out until
–6.0 to –8.0 mid-June when nut sizing is completed.
Mild to moderate stress—shoot growth in nonbearing and bearing trees has been ob-
–8.0 to –10.0 served to decline especially with black walnut rootstock. These levels do not appear to
–10.0 to –12.0 affect kernel development and may be appropriate during kernel development.
–12.0 to –14.0 Moderate to high stress—shoot growth in nonbearing trees may stop, nut sizing may be
–14.0 to –18.0 reduced in bearing trees.
High stress—temporary wilting of leaves has been observed. New shoot growth may be
sparse or absent and some defoliation may be evident. Nut size likely to be reduced.
Relatively high levels of stress—moderate to severe defoliation, should be avoided.
Severe defoliation, trees are likely dying.

10 G R O W E R N E W S

Meet two WORLD WALNUT OUTLOOK
new walnut
farm advisors Spotlight on India

Carolyn DeBuse Production
brings a background Available walnut production for the 2007/08 marketing year was forecasted at 37,000
in pomology and a com- tons (inshell basis), slightly lower than the prior year’s record crop of 40,000 tons. Be-
mitment to the orchard cause walnuts in India are mainly dryland farmed on soils with lower fertility, yields
industry in joining the per acre are relatively low, averaging approximately one-half ton per acre. Walnuts are
Solano and Yolo County grown mainly in the Jammu and Kashmir regions, with minor production occur-
Extension team. ring in the Himachal Pradesh and Uttarakhand areas. Indian walnuts are classified
She holds an under- as hard, medium or thin shell, with nut sizes ranging from 24–32 mm. The average
graduate degree in plant shelling rate is 40%, but can be higher on the “Bakshi” variety. The end of August
science–pomology and a master’s degree through September is the typical harvest season with peak shipments occurring in late
in horticulture and agronomy from UC October.
Davis. Before joining the Extension staff,
she spent eight years working for the UC Domestic Consumption
Dried Plum Cultivar Improvement Pro- Due to tight supplies and lower almond prices, domestic walnut consumption for
gram as the plant breeder and program 2007/08 is expected to be 20,900 tons, approximately the same as the prior year.
manager. Better consumer packaging (vacuum packs that improve shelf life and quality) has
Her areas of research include :cul- encouraged middle-class consumers to eat walnuts as a year-round snack. Walnuts
tivars with varying maturity dates, new were typically priced below other competing nuts, but the vacuum-packed walnut
disease- and pest-resistant rootstock and kernels are securing higher prices.
codling moth control.
DeBuse can be contacted at (707) Exports
784-1320 or [email protected]. Because of the strong value of Indian rupees vis-à-vis other currencies, exports are
anticipated to decline to 16,500 tons on tight supplies due to strong domestic de-
David Doll joins mand. If supplies improve for 2008/09, exports are expected to recover to 19,000 tons.
Merced County Major export destinations for India are the E.U. and Middle East countries,
Extension office coming with more than 95% of the sales exported as kernels in vacuum packs. In descend-
from UC Davis, where ing order, Spain, France, Germany, United Kingdom and Egypt are the largest export
he has been doing plant destinations for Indian walnuts.
pathology research. Doll
holds a B.S. in plant Trade Policy Walnut Production
biology from Purdue While there are no volume and Distribution
University and a M.S. in restrictions on imports, a
plant pathology from UC Davis. duty of 30.9% is applied to (in tons)
Doll hails from southeastern imported walnuts, which will
Indiana. Prior to taking the job, he spent continue to limit the amount Marketing Year 2006/07 2007/08
four years researching replant problems of imports. 90,400
of almonds and determining alternatives Acres Planted 90,400 76,076
to methyl bromide fumigation, research 2,400
he plans to continue. Other research in- Bearing Acres 76,076 37,000
terests include reducing volatile organic 0
compounds (VOCs) and greenhouse gas Beginning Inventory 3,400 39,400
emissions, and plant diseases. 16,500
He can be reached at the Merced Production 40,000 20,900
County Cooperative Extension Office at 2,000
(209) 385-7403 or [email protected]. Imports 0

Total Supply 43,400

Exports 19,800

Domestic Consumption 20,800

Ending Stocks 2,800

G R O W E R N E W S 11

Diamond Foods, Inc.
1050 S. Diamond St.
Stockton, CA 95205

Diamond relaunches corporate website

Diamond has relaunched its corporate website diamondfoods.
com and introduced a consumer site dedicated to the
Diamond of California brand at diamondnuts.com.
The redesigned Diamond Foods corporate website features
improved site-wide navigation and a bold new design that highlights
the latest packaging and product innovations across the various
product lines: Diamond Culinary Nuts and Emerald Premium Snacks.
“The all-new Diamond Nuts brand site invites consumers to
expand their thinking of culinary nuts beyond baking,” said Jeff Ngo,
senior marketing manager for Diamond Foods. “With a plethora
of delicious recipes, the site offers fresh ways to add flavor, crunch,
nutritional value and variety to everyday cooking and special
occasions. From Butternut Squash Risotto with Walnuts and Arugula
to Post-Thanksgiving Turkey Enchilada Casserole, the recipe interface
encourages consumers to explore and share the many possibilities of
cooking with nuts.”
In the new “Celebrity Kitchen” section, visitors can also discover nut recipes
and cooking techniques from celebrity chefs, including Martin Yan,
host of the popular TV series “Yan Can Cook” and
Tina Salter, well-known cookbook
author and TV show host. The site also
features a “Live Well” section, offering a
downloadable health brochure, “Nuts for
Healthy Living,” and valuable tips on how
nuts are an important part of a healthy
lifestyle.

diamondfoods.com
diamondnuts.com

© 2008 Diamond Foods, Inc. Published by Diamond Foods, Inc., 1050 S. Diamond St., Stockton, CA 95205 • 209-467-6000 • diamondfoods.com
Articles appearing in this publication may not be reprinted without permission. Please address any comments or
suggestions to Sam Keiper, Vice President of Corporate Affairs, at the address above.