Nutrition of Blueberries & Implications
For Fertilization
Dr. Bernadine C. Strik
Professor
Dept. Horticulture
Oregon State University
Fertilizer requirements
How much does the plant need?
What is already available?
When does the plant need the nutrient?
How is the fertilizer taken up by the plant?
How mobile is the nutrient?
What source of the nutrient is best?
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 1
Oregon State University1
Mobility in the Plant
• Mobile within the plant
– N, P, K, Mg, Cl
• Immobile within the plant
– S, Fe, Mn, Cu, Zn
• Very immobile within the plant
– Ca, B
Translocation Within the Plant
• Xylem (Water Pipes)
Dead: Everything goes to leaves with water
• Phloem (Sugar Pipes)
Alive: To move something out of a leaf requires the phloem
Nitrogen
Mobile in plant and soil
Vaccinium plants take up ammonium (NH4+) form
N is present in many essential compounds
General chlorosis along with reddish tinge when deficient;
poor growth
Excess N will increase vigor, may decrease yield &
quality
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 2
Oregon State University2
Nitrogen Source
• Blueberry plants use the ammonium form of N (NH4+)
• Fertilizer programs that contain only nitrate (NO3-) should
be avoided!
• Do not use ammonium sulfate if the soil pH is below 5
unless you add lime
Nitrogen fertilizer rate studies in Vaccinium
Results from applying various rates of N fertilizer in trials
with blueberry have been variable throughout world
Variability in results may be partially due to soil fertility,
existing plant vigor or age (stored reserves), length
of study, and method of fertilization
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 3
Oregon State University3
Nitrogen fertilizer rate studies – Granular
• In 5-year study on „Bluecrop‟ in Michigan, split applications
of 75 lb N/a had higher yield than no fertilizer
(Hanson and Retamales, 1992)
• In Arkansas, yield of „Collins‟, applying 65 or 130 lb N/a
reduced yield compared to 20 lb N/a over two years
(Clark et al., 1998) and in an 8-year study, there was no
benefit to fertilizing with more than 30 lb N/a (Cummings, 1978)
• In Oregon, in a 2-year study in mature „Bluecrop‟, there was
no difference in yield between 0, 100, and 200 lb N/a
(Bañados et al., 2006)
and
• Fertilization with low to high rate (50 to 240 lb N/a) of N for
7 years in Elliott has had no effect on yield to date (Strik et al)
Nitrogen fertilizer rate studies – Granular
• In Oregon, in establishing plants, the best rate (of 0, 50, 100,
and150 lb N/a) of granular in new fields was 50 lb N/a
(Bañados et al., 2006)
• In an organic study in Oregon, the best rate of fish emulsion
and feather meal was 25 and 50 lb N/a, respectively, in
the first three years of growth. (Larco et al., 2011)
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 4
Oregon State University4
Fertilizer uptake and partitioning (15N)
Granular
Nitrogen fertilizer uptake studies using 15N have been done
in field-grown blueberry (Throop and Hanson, 1991; Retamales and
Hanson, 1989; Bañados, 2006; White, 2006).
• Plants absorb fertilizer N more efficiently from late bloom
through fruit maturity
• Fertilizer uptake efficiency from granular products is low,
and thus multiple applications are recommended
Time first application at
bloom or early shoot
growth
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 5
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Second application
in May
Third application in June
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 6
Oregon State University6
„Liberty‟, 3-year old, Oregon
Drip irrigated and fertigated
Southern highbush, three-year-old, in California
Fertigated
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 7
Oregon State University7
Fertilization with drip irrigation
“Fertigation”
Nitrogen fertilizer rate studies using fertigation are limited
(Bryla, in progress; Finn and Warmund, 1997; Williamson and Miller,2009)
• In Missouri, northern HB blueberry had larger size and
higher yield in year 3 and 4 when fertigated with N compared
to same rate of granular N at bud break + 6 or 12 weeks –
thought related to improved efficiency (Finn and Warmund, 1997)
• In pine bark system in FL, canopy growth and yield of Misty
and Star increased with rate of N fertigated (likely due to
limited water and nutrient holding capacity of bark) up to 260 lb N/a
and
• Granular (applied monthly Mar-Oct) or fertigation every
2 weeks (Mar-Oct) led to slightly higher yield with granular
(Williamson and Miller, 2009)
Fertilization with drip irrigation
“Fertigation”
Nitrogen fertilizer rate studies using fertigation are limited
(Bryla, in progress; Finn and Warmund, 1997; Williamson and Miller,2009)
• In Oregon, granular with ammonium sulfate or urea &
micro-spray sprinklers is being compared to drip fertigated
at rates from 0 to 225 lb N/a
• In granular applications, high rates lead to high EC (salt)
and plant stress
• In fertigated plantings, higher rates of N may not increase
yield, but have not lead to salt injury to date
(David Bryla, USDA-ARS, Corvallis, work in progress)
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 8
Oregon State University8
Fertigation (drip) vs. Granular Fertilizer (sprinklers)
Fertigation (ammonium sulfate)
Fertigation (urea)
Granular (ammonium sulfate)
Granular (urea)
0.8
a
a
a
a
a
a
a
a
a
a
b
b
a
0.6
0.4
a
b
b
Method (M) **
N rate (N) **
M x N **
0.2
0.0
0
60
120
a
a
1.8
a
1.6
b
1.2
b
b
180
b
b
67
133
a
4.0
a
Method (M) NS
N rate (N) **
M x N **
0
2010 (Year 5)
4.5
a
ab
a
a
1.4
1.0
N application (lb/acre)
a
a
a
2.0
Yield (kg/plant)
Yield (kg/plant)
1.0
2009 (Year 4)
2.2
Yield (kg/plant)
2008 (Year 3)
1.2
Soil pH at planting
(Apr. 2006) was 6.1
a
ab
a
a
a
a
a
a
b
bc
Method (M) **
N rate **
MxN*
2.0
0
N application (lb/acre)
Irrigation manifold
a
ab
3.0
2.5
200
a
a
3.5
75
c
150
225
N application (lb/acre)
N fertigation
Harvest in 2008
Vargas & Bryla (unpublished data)
Rate and Timing of N application
impacts on fruit N
Rate of N applied (lb N/a)
N concentration in fruit
(%N)
0
0.72
100
0.68
200
0.93
Bañados and Strik, 2004
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 9
Oregon State University9
Soil solution sampler
2
Continuous fertigation Weekly 4/18-8/15
1
0
NH4 -N (ppm)
1000
+
800
Granular fertilizer
Fertilizer applications
0 lb N/acre
45 lb N/acre
89 lb N/acre
134 lb N/acre
(4/18; 5/16; 6/13)
600
400
200
0
Apr
May
Jun
Jul
Aug
Sep
Oct
2007
Courtesy: Dr. Dave Bryla, ARS-USDA, 2008
Soil solution sampler
Weekly 4/18-8/15
Continuous fertigation
1
-1
Electrical conductivity (mS cm )
2
0
8
Granular fertilizer
0 lb N/acre
45 lb N/acre
89 lb N/acre
134 lb N/acre
(4/18; 5/16; 6/13)
7
6
5
4
3
2
1
0
Apr
May
Jun
Jul
Aug
Sep
Oct
2007
Courtesy: Dr. Dave Bryla, ARS-USDA, 2008
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 10
Oregon State University10
Nitrogen fertilizer rate studies
• N fertilization can increase yield through increased growth
however, there is often a threshold
• N fertilization may impact next year‟s yield through effect
on flushes of growth and subsequent flower bud initiation
and by increasing winter cold damage
Lateral shoot
from one-year-old
wood
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 11
Oregon State University11
Effect of N fertilization rate of „Bluecrop‟ at 0.45 m and
1.2 m spacing on shoot growth in 2002
0.45
0.4
Fruit harvest
growth (cm/d)
0.35
0.45 m 0 kg N
0.45 m 100 kg N
0.45 m 200 kg N
1.2 m 0 kg N
1.2 m 100 kg N
1.2 m 200 kg N
0.3
0.25
0.2
0.15
0.1
0.05
High rates of N force later flush of growth
Late fertilization with N forces late growth
12-Aug
29-Jul
15-Jul
1-Jul
17-Jun
3-Jun
20-May
6-May
22-Apr
8-Apr
25-Mar
0
Reduce bud set
Increase cold damage
Bañados and Strik, 2004
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 12
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Growth rate of whips in Elliott as affected by production system
Year 1
Daily Growth (cm/d-1)
2004 Daily Whip Growth - Pre-Plant Incorporation
1.4
1.2
No mulch, 22N
1
No mulch, 68N
0.8
No mulch, 114N
0.6
Mulch, 22N
0.4
Mulch, 68N
0.2
Mulch, 114N
23-Sep
9-Sep
26-Aug
12-Aug
29-Jul
15-Jul
1-Jul
0
White and Strik, 2006
Bluejay
Liberty
Sept. 29, 2007
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
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Liberty
How much N is tied up in fresh sawdust mulch?
• 3” deep 2‟ wide
sawdust mulch
centered on rows:
• Fresh sawdust
immobilizes 0.1 % N
• = 25 lb N/a
Fresh sawdust (C:N =800)
Yang,2005
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 14
Oregon State University14
Adjust N fertilizer when using mulches based on C:N ratio
Weed mat, Duke, Oregon
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 15
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Nitrogen (N)
Mobile in plant and soil
Vaccinium plants take up ammonium (NH4+) form
N is present in many essential compounds
General chlorosis along with reddish tinge when deficient;
poor growth
Excess N will increase vigor, may decrease yield &
quality
Phosphorus (P)
Early season P deficiency
due to cool soil temperature
Mobile in plant, but very immobile in soil
Involved in photosynthesis, other metabolic processes
and part of DNA and RNA
P deficient plants are stunted and often dark green;
leaves may have red tinge due to accumulation of
anthocyanins
Excess P will increase root to shoot ratio
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 16
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Potassium (K)
Mobile in plant, but immobile in soil
Activator of many enzymes essential
for photosynthesis & respiration, and
to form starch and proteins; related to
osmotic potential and turgor pressure
Tissue levels related to crop load
Adequate levels needed for firmness?
K toxicity
K deficient plants have older leaves with necrotic lesions
High soil K and low leaf %K often related to production
problems
Magnesium (Mg)
Mg deficiency
Mobile in plant, but immobile in soil
Present in chlorophyll molecule, combines with ATP,
activator of many enzymes essential for photosynthesis,
respiration, and to form DNA and RNA
Deficient plants have older leaves with interveinal necrosis
or edges starting red and turning brown
Deficiencies more common on sandy soil with low pH or if
soil K is high
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
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Oregon State University17
Sulfur (S)
S toxicity
 Moves with water in transpiration stream
 Required for protein synthesis
 Deficiency symptoms rare in blueberry due to use of
fertilizers with sulfate
 Toxicity often reflected as “salt injury” (see photo)
Uptake is not sensitive to soil pH
Calcium (Ca)
Ca deficiency
omafra.gov.on.ca
Immobile in plant and soil; moves in xylem
Required for cell division, to form cell walls, and normal
membrane functions; Ca concentrations in cells are usually
kept low by plant to prevent formation of salts; many
enzymes are inhibited by high Ca in cells
Deficiency symptoms in younger leaves; deformed, twisted
tissues; low Ca may reduce fruit firmness
Low soil moisture & cool, cloudy, humid conditions limit %Ca
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 18
Oregon State University18
Test Time!
 Your grandma has osteoporosis?
 Should you feed her lots of lettuce or lots of
apples?
 Why?
1 cup fresh lettuce has ~ 10 mg Ca
1 cup fresh apple has ~ 7.5 mg Ca
Iron (Fe)
Immobile in plant and soil
Required for chlorophyll formation; forms part of
enzymes and proteins
 Fe is internally precipitated in cells or formed into insoluble
compounds
Deficiency symptoms in younger leaves; interveinal
chlorosis
Fe is more available in soil at lower pH & may form
insoluble precipitates with excess P
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 19
Oregon State University19
Manganese (Mn)
Immobile in plant and soil
More available at low pH
Required for chlorophyll formation and activation of
enzymes; may be involved in auxin regulation
 Deficiency symptoms in younger or older leaves
depending on species; interveinal chlorosis
 Toxicity may occur in blueberry
Toxicity, blueberry
Boron (B)
Very immobile in plant; mobile in soil
Required for normal root tip elongation, cell division in shoot
tip; required for normal elongation of pollen tubes
 Deficiency symptoms vary depending on plant species, but
may reduce berry size (seed number) and bud break
Toxicity can occur – tip burning of shoots
Annual applications, without soil or
tissue tests not recommended
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Toxicity, grape
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Zinc (Zn)
Immobile in plant; very immobile in soil
Required for chlorophyll synthesis and auxin production;
required for function of many enzymes
 Deficiency symptoms include little leaf and rosette growth;
leaf margins often distorted and leaves puckered;
interveinal chlorosis often present
Zn is more available at low pH
Nutrient content (g/plant)
Nutrient accumulation
for the whole plant
New shoots &
Leaves accumulate
nutrients all season
Nutrients are lost in
leaves at senescence
Losses of N and K in
woody tissue in early
spring
Gains in macronutrients
in late season
Nutrients lost with pruning
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
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Nutrient accumulation
for the whole plant
Nutrient content (g/plant)
Growth of crown
and roots occurs in
late summer (both)
and spring (roots)
Losses of N,P,K,Ca,
Mg in crown in
early spring, gains in
late season
Losses in roots in
mid-summer, gains in
fall-winter
Nutrients removed in fruit for 9 ton/acre yield. „Bluecrop‟ as
affected by N fertilization rate (avg. 2 years), machine
harvest
Nitrogen Rate
(lb/a)
100
200
Nutrient removed with 9 ton/acre yield (lb)
N
P
K
Ca
Mg
19
3
26
2
1
38
3
28
2
2
Nutrient removed per 9 ton/acre yield (g)
B
Fe
Mn
Cu
Zn
15
57
76
4
10
14
66
56
4
11
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 22
Oregon State University22
Soil & tissue testing are important to determine fertilizer needs
• Keep records of weather, plant health, fertilization,
irrigation, and plant growth
• Adding more fertilizer will not compensate for other limiting
factors
• Soil sampling should be representative, reflecting
management unit
• Take soil test before planting
• Do soil analysis every 2 to 4 years
• Do annual tissue analysis (to compare to critical values
and to establish trends)
• For diagnosis of problems or fixing problems, do both
soil and tissue testing
Suggested soil nutrient deficiency levels
Nutrient
pH (in water)
Unit
target:
4.5 to 5.5
Deficient at less than:
Phosphorus (P; Bray)
Phosphorus (Olsen)
Potassium (K)
Calcium (Ca)
Magnesium (Mg)
Manganese (Mn)
Boron (B)
ppm
ppm
ppm
ppm
ppm
ppm
ppm
EC
na=not available
dS/m
25 to 50
10
100 to 150
1000
60
20
0.5
80
2
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 23
Oregon State University23
Why soil pH is important to blueberry
production
• Blueberries grow best when the soil pH is between 4.5 and
5.5
• Soil pH is changed by cultural practices such as liming and
N fertilizer, especially ammonium sulfate
• Blueberry plants don‟t grow well outside optimum pH range.
Yellow plant
Rabbiteye field
Soil pH 6.1 in top 2 inches
Soil pH 5.6 from 2 to 6 inches
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 24
Oregon State University24
Lime induced iron deficiency
Rabbiteye
Highbush
Why do blueberries have iron deficiency?
Iron in Solution, mg/l
• Iron availability decreases as the soil pH increases
• Blueberries seem to be inefficient at taking iron from
soil with a pH above 5.5
Soil pH and iron in soil solution
0.12
0.09
Bashaw soil
0.06
0.03 Woodburn soil
0
3.5
4.5
5.5
6.5
7.5
Soil pH
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 25
Oregon State University25
Element
Fe
Expected
Range
61 to 200 ppm
29 ppm
46ppm
Leaves from the same plant
Soil pH influences the root
environment by
• Controlling the solubility of toxic materials such as
aluminum (Al) and manganese (Mn)
• Reducing the bacterial population that changes
ammonium (NH4+) to nitrate (NO3-) as the soil pH
declines. The NH4+ form of N has been shown as the
only N form blueberries use
• Controlling the solubility/availability of nutrients.
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 26
Oregon State University26
pH too low
in established
planting, Oregon
2007
High rates of N fertilizer
will lower pH.
If pH is below 4.2 we
see problems…..
Leaf Sampling Concepts
 Leaf concentrations depend on tissue type
and tissue age
 Physiological age is more important than a
calendar time
 There is no one perfect sample tissue or
sample time for all elements
 Procedures used are a compromise
 Pick a procedure and stay with it
 Looking at long term trends is as important
as critical values at a given time
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 27
Oregon State University27
Sample most recent fully-expanded
leaves in late-July to early August
in PNW
4
Leaf N, %
3
2
„Elliott‟
8-11-06
1
0
13-May
12-Jun
12-Jul
11-Aug
10-Sep
10-Oct
9-Nov
Date
Bluecrop
Table. Blueberry leaf N sufficiency, late July–mid August sampling
Leaf N
Status
(%)
<1.50
deficient
1.51–1.75 below normal
1.76–2.00 normal
2.01–2.50 above normal
>2.50
excess
Suggested critical levels for leaf nutrient concentrations
(most recent fully expanded leaves) – late July/early Aug;
after harvest in PNW
Nutrient
Northern
Nitrogen (%N)
Phosphorus (%P)
Potassium (%K)
Calcium (%Ca)
Magnesium (%Mg)
Sulfur (%S)
Manganese (ppm Mn)
Boron (ppm B)
Iron (ppm Fe)
Zinc (ppm Zn)
Copper (ppm Cu)
na=not available
1.7
0.07
0.2
0.2
0.1
0.07
10
20
50
4
2
Deficient below
Southern Rabbiteye
1.7
0.1
0.3
0.12
0.08
0.1
23
20
60
8
5
1.7
0.1
0.3
0.12
0.08
na
23
20
60
8
5
Northern
Sufficient
Southern
Rabbiteye
1.76 to 2
0.11 to 0.4
0.41 to 0.7
0.41 to 0.8
0.13 to 0.25
0.11 to 0.16
31 to 350
31 to 80
61 to 200
8 to 30
5 to 15
1.8 to 2.1
0.12 to 0.4
0.35 to 0.65
0.4 to 0.8
0.12 to 0.25
0.12 to 0.25
50 to 350
30 to 70
60 to 200
8 to 30
5 to 20
1.2 to 1.7
0.08 to 0.17
0.28 to 0.60
0.24 to 0.7
0.14 to 0.2
na
25 to 100
12 to 35
25 to 70
10 to 25
2 to 10
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Excessive above
Northern
Southern Rabbiteye
2.5
0.8
0.95
1
0.45
0.2
450
150
400
80
50
2.5
0.8
0.95
1
0.45
na
450
200
400
80
100
2.5
0.8
0.95
1
0.45
na
450
200
400
80
100
Page 28
Oregon State University28
http://extension.oregonstate.edu/catalog/
One acre
Plant
Grass
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 29
Oregon State University29
One acre
Plant
Grass
Total fertilizer required/acre is applied as broadcast band
Can plants take up nutrients through leaves?
• Plants take up most nutrients through roots, but leaf
uptake is possible
• Major limiting factor is how much fertilizer can be added
to leaf surface before burning occurs
• It is almost impossible to supply a significant portion of the
macronutrient needs of the plant with a foliar program –
would require almost constant feeding with low
concentrations
• Targeted micronutrient applications can supply a large
portion of nutrient relative to plant demand
• For a nutrient to enter the leaf, it must penetrate the
cuticle
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 30
Oregon State University30
Efficiency of uptake
• smaller molecules have better penetration
• waxy cuticle is major barrier to movement
• areas near veins, stomata, younger leaves
have better penetration
• water stress can lead to thicker cuticles
reducing penetration
• low relative humidity and rain reduce efficiency
• formulations important (chelates, buffers, surfactants…)
• every foliar application is a combo of foliar + ground
What about foliar “feeding”?
For N:
Maximum concentration is 5%
urea in water (= 14 lb N/a)
In other perennial crops,
maximum uptake through
leaves + roots has been 50% (= 7 lb N/a)
Foliar applications are sometimes an effective method of
correcting micronutrient deficiencies (specific or special
situations)
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 31
Oregon State University31
Tunnel production will affect nutrient requirements
Summary
Understanding nutrient mobility is important
Nutrients required are affected by plant age,
canopy size, yield, time of year
Fertilizer to apply depends on method of
application and amount of nutrient needed
Test for soil nutrient status (pH) and adjust
if needed
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 32
Oregon State University32
Summary, Cont.
Tissue testing is important to determine plant
nutrient status
Don‟t rely on standards for tissue testing at other
times of year
Goal is to ensure adequate nutrients are available
when they are needed (e.g N for growth; Ca for
fruit development and growth; K for fruit; P for
root growth)
Choose fertilizer formulations that are best for
blueberry
Native Vaccinium, Lake Scott, Ore.
Bernadine C. Strik, Professor, Oregon State University
Dr. Bernadine C. Strik, Professor
Page 33
Oregon State University33