investigations into the use of stevia as a rotation crop ... · h. david shew....
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Investigations into the use of stevia as a rotation crop in
tobacco production systems
Alyssa M. Koehler and H. David Shew
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Stevia rebaundia
• Herbaceous perennial of family Asteraceae
• Native to South America, first documented in Paraguay
• 300 times sweeter than sucrose
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Stevia Glycosides • Sweetness comes from diterpene glycosides • 13 glycosides have been identified
• stevioside: highest proportion • rebaudioside A (Reb-A): most desirable flavor profile• Other minor rebaudiosides are under investigation
• Glycosides are found in the leaves• These compounds are non caloric and have no
nutritional value because they are not digested or absorbed by the body
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Stevia World Usage • First used in South America, Japan, and other Asian countries • Currently available in 75 countries around the world• Approved by the USDA as a non-nutritive sweetener in 2008• Stevia global market value of $336 million in 2014, estimated to
reach $578 million by 2017
33%
30%
25%
11%
1%
Stevia Sales Volume Shares in 2013
1
2
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4
5
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Stevia in the Southeast
The climate and soil conditions of NC and GA are well suited for stevia production
Existing Infrastructure• Tobacco float trays • Transplanters• Field equipment• Tobacco barns/peanut trailers
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Stevia Production
Raw seedDe-bearded Seed
Pelletized Seed
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Transplanting Stevia
28,000-35,000 plants per acre Perennial crop managed for 3-5 years
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Stevia Harvesting • Harvested with a combine
or available equipment • 1 harvest in first year crop• 2 harvests in 2nd and 3rd
year crops • July and September
• Harvest prior to flowering
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Post Harvest
Dried bales are shipped to China for extraction
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Stevia Production in NC
First planting in 2011 - one field in Bertie County
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Stevia Production in NC
• Acreage expanded2012 -2015
• ~ 500 acres currently in production
• Contract with Sweet Green Fields
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Organic Tobacco Production
• Best management practices recommend following a rotation
• Corn, beans, etc.• Until products are
labeled, all stevia must be organically produced
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Advantages of Stevia as a Tobacco Rotation
• Stevia is a perennial crop• Stevia production has a strong infrastructure
overlap with tobacco production • Seedling production • Transplant equipment• Drying
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Challenges for Establishing a New Crop
• Transplant production • Germination rate• Seedling production
• Fertility • Weed Management
• Glyphosate registered for use on dormant plants
• Disease Management • No products labeled
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Screening Tobacco Diseases No Symptoms on stevia • Granville Wilt (Ralstonia solanacearum)• Black Shank (Phytophthora nicotianae)• Fusarium (Fusarium oxysporum)• TMV
Stevia growing in Black Shank disease nursery
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Disease Scouting in NC
2012: 1st major pathogenSclerotium rolfsii
2013: 2nd major pathogenSclerotinia sclerotiorum
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Disease in NCSclerotium rolfsii Sclerotinia sclerotiorum• Wide host range• Indigenous to NC• Kills with oxalic acid• Infection – hyphae
from sclerotia• Infection occurs all
season; growth between stems
• Wide host range• Indigenous to NC• Kills with oxalic acid• Infection by ascospores
early in the season • Only early season
infection; no secondary spread
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AA A
AAB AB AB AB
BC
C
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10
Mea
n %
Dis
ease
Treatments
Treatment Effects of Fungicide and Biocontrol Products on Percent Disease Caused by
S. rolfsii on Stevia in 2014 2016
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A A A A AA A AB AB
B
0500
100015002000250030003500400045005000
1 2 3 4 5 6 7 8 9 10
Yiel
d (k
g/ha
)
Treatments
Stevia Yield (kg/ha) from 2014 S. rolfsii Fungicide and Biocontrol Trial
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A A AA A A A A A A
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10
Mea
n %
Dis
ease
Treatments
Treatment Effects of Fungicide and Biocontrol Products on Percent Disease Caused by S. rolfsii on
Stevia in 2015 2016
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A AB BC
C C
CDD D D
0
500
1000
1500
2000
2500
1 2 3 4 5 6 7 8 9 10
Yiel
d (k
g/ha
)
Treatments
Stevia Yield (kg/ha) from 2015 S. rolfsii Fungicide and Biocontrol Trial
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Disease in 2015Septoria leaf spot TSWV
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Septoria• Present in greenhouse production system and
planted into fields in 2015, also present on 2nd
year plants in Kinston and other locations• Species and sources of inoculum need identified• Fungicide trials will be added for 2016 season • May represent the greatest threat to yields among
diseases observed so far
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TSWV• Seen in the greenhouse, no known field sightings • Unknown as to potential for losses under field
conditions
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Conclusions • Stevia is not affected by pathogens that cause
Granville Wilt, Black Shank, or Fusarium wilt of tobacco
• Important pathogens of stevia are not of major concern in tobacco production
• Stevia is an exciting new crop with potential for use as a rotation crop in organic and traditional production systems including tobacco
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Acknowledgements Funding Sources
• NC Tobacco Foundation, Inc. • NC Tobacco Trust Fund
Commission• RJ Reynolds Tobacco Company
- Fund of Excellence • Sweet Green Fields – germplasm
Committee • Dr. David Shew • Dr. Marc Cubeta• Dr. Lina Quesada
Shew Lab • Kestrel McCorkle• Arlene Mendoza-Moran• Cody Baker • Austin Kinley
• Field Staff at Caswell Research Station
• Field Staff at Upper Coastal Plain Research Station
• Sarah Seehaver• Chris Reberg-Horton
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Production and Disease Management Field Day June 2014
Introducing growers to stevia production
Planting demonstration
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Stevia Production Field Day August 2014
Growers and agents from conventional and organic backgrounds
Fungicide and biocontrol trials for S. rolfsii
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