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Fertility Affects Susceptibility of
Chrysanthemum to Cotton Aphids Influence on
Plant Growth, Photosynthesis, Ethylene Evolution
and Herbivore Abundance Fred Davies, Chuanjiu
He, Amanda Chau Kevin Heinz, Carlos Bográn and,
Scott Ludwig
(J. Amer Soc Hort Sci. 129344-353, 2004)
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Host Plant/Crop Greenhouse mum Charm
Biotic Stress Aphids Abiotic Stress
Fertility Objectives Determining
fertility and aphid influence on plant
growth development and herbivore (NO
PESTICIDE STRESSES ADDED) Treatments
2 ? aphid levels x 5 fertility levels 10
trts.
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Quick Rinse of Aphid Exudate
Bottom Middle Apical
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Total Bud DM (g)
0 19 38 75 375
Fertility Level (ppm N)
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Leaf DM (g)
Fertility Level (ppm N)
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Total Leaf Area (cm2)
0 19 38 75 375
Fertility Level (ppm N)
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Specific Leaf Area (cm2 g-1)
Fertility Level (ppm N)
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Ethylene Production Rate (pmol g-1 FW h-1)
Buds Young Phys. Mat Old
Leaf Leaf Leaf
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Pn (?mol CO2 m-2 s-1)
Young Phys. Mat Old Leaf
Leaf Leaf
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Young Leaves
N ()
Phys. Mat Leaves
0 19 38 75 375
Fertility Level (ppm N)
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Aphids No.
Fertility Level (ppm N)
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• Summary
• REDUCED PLANT QUALITY Aphids depressed plant
  vegetative and reproductive growth, and altered
  carbohydrate partitioning at high fertility.
• Aphid inoculated (AI) plants at high fertility
  had increased specific leaf area (SLA), i.e.
  thinner leaves and greater leaf area than
  aphid-free (NonAI) plants.
• Aphids caused greater ethylene production in
  reproductive buds and young leaves of high
  fertility plants, but had no effect on ethylene
  evolution in physiologically mature or older -
  basal leaves.

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• Summary (con.)
• AI plants had lower leaf N than NonAI
  treatments.
• Aphids reduced photosynthesis in young leaves of
  high fertility plants, whereas
  physiologically mature and older leaves were
  unaffected.
• Aphid abundance was greatest at high fertility.
• A higher proportion of aphids were observed in
  physiologically mature and older leaves at low
  fertility, whereas at high fertility young leaves
  had 33 more aphids than older, basal leaves.

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Manipulating Fertility Affects Susceptibility
of Potted Chrysanthemum to Western Flower Thrips
(Frankliniella occidentalis)? Abundance and
Influence on Plant Growth Fred Davies, Chuanjiu
He, Amanda Chau, Kevin Heinz, James Spiers,
Carlos Bográn, Scott Ludwig
(J. Hort Sci Biotech. 80 403-412 , 2005)
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Host Plant/Crop Greenhouse mum Charm
Biotic Stress Thrips Abiotic Stress
Fertility Objectives Determining
fertility and aphid influence on plant
growth development and herbivore (NO
PESTICIDE STRESSES ADDED) Treatments
2 ? thrips levels x 4 fertility levels 8
trts.
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A
B
C
FIG. 1
D
E
F
E
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• Summary
• REDUCED PLANT QUALITY Western Flower Thrips
  (WFT) depressed plant vegetative and reproductive
  growth, and altered carbohydrate partitioning at
  high fertility.
• WFT inoculated plants had reduce leaf area
  mass.
• Leaf stomatal conductance was more sensitive to
  WFT damage than net photosynthesis.
• WFT reduced vegetative reproductive growth
  primarily through reduced net photosynthesis
  stomatal conductance.

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• Application to Stakeholders
• The morphology and physiological status of
  chrysanthemum determines its susceptibility to
  aphids and WFT.
• Aphids increase ethylene both WFT Aphids
  decrease net photosynthesis, and decrease carbon
  allocation to leaves and reproductive structures,
  particularly at higher fertility.
• While growing plants under deficient fertility
  levels is not a satisfactory strategy for
  reducing insect pests, reducing fertility and
  pesticide levels and producing healthier, less
  stress susceptible plants is a realistic endeavor
  for best management practices (BMP) and IPM
  systems.

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Experiment Harvest
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Insecticides from Five Chemical Classes
Differentially Affect the Plant Growth and
Development of Potted Gerberas (Gerbera jamesonii
Festival Salmon)

• James Spiers, Fred Davies, Chuanjiu He, Carlos
  Bográn, Kevin Heinz, Terri Starman, Amanda Chau,
  Scott Ludwig
• (HortScience 41
  701-706, 2006)

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• Avid 0.15 EC, Talstar? Nursery Flowable, and
  Conserve SC did not alter plant gas exchange,
  and were not detrimental to plant growth and
  developmenteven when applied at 4X the
  recommended rate.
• Orthene? Turf, Tree Ornamental Spray 97 was
  phytotoxic at 4X rate, but did not adversely
  affect plant growth and development or plant gas
  exchange at 1X rate.

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• Triact 70 (hydrophobic extract of neem oil)
  reduced plant gas exchange, plant growth and
  development, and flower production, with greatest
  reductions occurring at the highest
  concentration.
• Insect infestations on some of the control plants
  and Talstar?-treated plants had the greatest
  negative impact on their commercially acceptable
  appearance, demonstrating the importance of
  insect pest control.

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Effects of Fertilization on the Host Plant
Resistance of Gerbera to Western Flower Thrips
James Spiers

• Overall Goals of Project
• Determine how fertilization affects the host
  plant resistance of Gerbera jamesonii to WFT by
  assessing feeding damage and WFT populations.
• Determine the effects of fertilization on both
  constitutive (naturally present) and induced host
  plant resistance.

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Constitutive Defenses

• Include stored allelochemicals that can reduce
  the attractiveness of plants to herbivores
• Possible roles of secondary metabolites in host
  plant resistance
• May decrease tissue digestibility and/or toxicity
  to herbivores.
• Influence herbivore feeding, oviposition, growth
  and development, fecundity, and/or fertility
  (Walling 2000).

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Effects of Nitrogen Availability on Secondary
Metabolites

• Increases in defensive compounds (peroxidase and
  total phenolics) due to N deficiency was shown to
  negatively effect feeding and oviposition of
  various insect herbivores in tomato (Inbar et
  al., 2001).

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Induced Resistance

• The phytohormone jasmonic acid (JA) is known to
  regulate many plant responses, including
  inducible defenses against insect herbivory.
• Many proteins and secondary metabolites that
  accumulate after wounding and JA-treatments
  interfere with insect feeding, oviposition,
  growth and development, and fecundity. .

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Effects of Fertilization on Total Phenolics in
Gerbera
High
Low

• Low Fertility Plants
• 10X higher concentration of total phenolics when
  compared to high (recommended rate) fertility
  plants.
• Young leaves had greater concentrations of
  phenolics compared to physiologically mature
  leaves.

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Effects of Fertilization on Host Plant Resistance
of Gerbera to WFT

• Plants were fertilized with 200 mL of Peters
  Professional Peat-Lite special 15N-16P-17K at 0,
  60, or 200 mgL-1 N, which is respectively, 0,
  30, or 100 the recommended rate.

• Currently determining Fertility WFT
  Effects on Jasmonic Acid Phenolics

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• SUMMARY
• Multidisciplinary approach Entomology,
  Horticulture, Plant Pathology.
• Discovery Translational Implementation
• Research to date is optimizing fertility,
  insecticides natural enemies Multiple
  Systems Approach

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• This Project has Generated
• 15 Peer reviewed publications guarantee
  scientific rigor
• 50 grower- and industry-related materials
  immediate impact.
• Training of Students Post-Docs perpetuate
  industry benefits.
• Establishment of numerous demonstration research
  locations to facilitate grower assessment,
  education adoption.
• Financial leveraging at rate of 2 for every
  provided by USDA-ARS.

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