Effects of Sustainable and Conventional Fertilizers on Plant
Growth and Insect Life History Traits
Katie England, Clifford SadofDepartment of Entomology, Purdue University
13 December 2009
Introduction
• Greenhouse growers are less likely to adopt sustainable production practices if they feel the difficulty or risk of switching practices is too great – (Hall et al. 2009)
Fertilizers
• Conventional fertilizers
– High energy inputs (Bhat et al. 1994)
– Mining of phosphorus and potassium (Ludwick et al. 1995)
– Potential for run-off and environmental degradation (Carpenter et al. 1998)
http://www.noble.org/Ag/Economics/FertilizeOrNot/Fertilizer.gif
• Oilseed extract– Daniels Plant Food
• P is from oilseed waste, not mineral deposits
• Nitrogen composition– 73.5% NH3 – 19% NO3 – 7.5% other
http://whyfiles.org/241GM_2/images/soybean_field.jpg
Commercial Alternative Fertilizer
http://www.gardeningthings.com/sm/cimpublic/retrieve.cgi?catalog_id=1.11.56
How Does Nitrogen Affect Plant Growth?
• Plant Growth– Affected by nitrogen
• Concentration (Stratton et al. 2001; Rose & White 1994)
• Form (NH3 or NO3+) (Bar-Tal et al. 2001; Jeong & Lee 1992)
• Potential for ammonium toxicity (Cox & Seeley 1984; Weigle et al. 1982)
NHNH33NHNH33
NONO33++NONO33++
How Does Nitrogen Affect Plant Pest Populations?
• Insect Pests– Phloem feeders respond to nitrogen content of
plants (White 1978; Jauset et al. 1998; Nevo & Coll 2001)
• Whiteflies, aphids, mealybugs– Prefer higher N concentrations– Prefer certain N forms
Purdue Extension
Hypothesis
• Growth and development of plants and pests are determined by the concentration and the form of the fertilizer
• Evaluate the effects of various commercial fertilizers on poinsettia growth
• Evaluate the effects of these fertilizers on insect pest life history traits
Objectives
Purdue Extension
http://www.sxc.hu/photo/616668
• Fall 2008• Poinsettia (cv. Prestige Early Red)
– Long growing season – Easily manipulate pest infestation– Whiteflies are a key pest
Poinsettia Study
Poinsettia Fertilizers
Treatment Fertilizer N P K
Conventional WSF
Peters Excel (15-5-15 The Scotts Co.)
200 29 167 (ppm)
Sustainable WSF
Daniels Plant Food (10-4-3 DP Foods, LLC)
200 40 58 (ppm)
Controlled Release
Fertilizer
Osmocote PLUS (15-9-12 The Scotts Co.)
1.4 0.35 0.91 (g/pot)
Alternation WSFs - - -
No Fertilizer Clear Water - - -
Poinsettia Growth
Clear Excel Alt Daniels Osmocote
12 weeks after treatments began
2 December
Whitefly Life History Traits
Linear Contrast: (F(1,24) = 9.64, P = 0.0048)
Fertilizer Survivorship
(SEM) W-D (n)
Fecundity (SEM)
W-D (n)
Clear Water 0.414 (0.070) C 9 24.07 (8.49) NS 6
Excel 0.754 (0.057) AB 9 42.85 (4.98) NS 8
Alternation 0.829 (0.049) AB 10 45.37 (5.16) NS 5
Daniels 0.863 (0.049) A 10 25.67 (5.89) NS 9
Osmocote 0.735 (0.030) B 10 39.11 (3.09) NS 9
F=13.37, df=4,34 P<0.0001 F=2.45, df=4,23 P=0.075 NS Not significantly different(n) Number of samples evaluated
Amino Acids (nmol/ mg)
Fertilizer n Total (SEM) W-D Essential
(SEM) W-D
Shikimic (SEM)
W-D Shik/ Ess
(SEM) W-D
Clear Water 8 7.56 (2.10) C 0.894
(0.426) B
0.392 (0.190)
B 0.603
(0.099) A
Excel 8 12.98 (3.29) BC
1.19 (0.334) B 0.442
(0.090) B
0.488 (0.10)
AB
Alternation 9 19.29 (3.20) B
2.53 (0.521) B 0.710
(0.119) AB
0.308 (0.028)
BC
Daniels 9 38.99 (5.96) A
5.02 (1.08) A 1.20
(0.146) A
0.413 (0.032)
BC
Osmocote 9 15.44 (3.71) B
2.01 (0.576) B 0.792
(0.215) AB
0.274 (0.035)
C
F=8.37 df=4,30
P=0.0001
F=6.03 df=4,30
P=0.0011
F=3.77 df=4,30 P=0.0135
F=5.31 df=4,29
P=0.0025
Poinsettia Amino Acids
F(2,40)=10 P<0.001, R2= 0.334
Su
rviv
ors
hip
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.0 20.0 40.0 60.0 80.0
Total Free Amino Acids (nmol/mg)
Su
rviv
ors
hip
Conclusions
• Whiteflies– Whitefly survivorship showed no differences among plants
fertilized with conventional and sustainable WSFs
– Fecundity was lower on unfertilized plants and those fertilized with Daniels Plant Food than on plants in the other three treatments
– Trends support a combination of both nutrient limitation/toxicity and plant defense mechanisms
Fertilizer does affect plant growth and pest development, however the effects of switching from conventional fertilizers
to Daniels Plant Food are likely to be unnoticeable in a greenhouse setting
Acknowledgements
Guidance and Greenhouse Support:
Dr. Cliff SadofDr. Roberto Lopez
Dr. Luis Cañas Diane Camberato
Rob EddyDan Hahn
Materials Donations:The Scotts Company
Ball Horticulture CompanyPaul Ecke Ranch
Premier HorticultureMyers Lawn & Garden Group
Others:Nuris Acosta
Claudia Kuniyoshi John Larson Julia Prado
Marc Rhainds Christina ShortAriana TorresDamir Torrico
Carlos QuesadaFlor Quispe