A systems-based approach to developing
non-chemical alternatives to fumigation for Florida
Dan Chellemi, Erin Rosskopf, Nancy Burelle
Soil Disinfestation
A process used to rid the soil of pests
(weeds, pathogens, nematodes)
prior to planting a crop
Fundamental premise
Re-infestation occurs,
despite the effectiveness
of pre-plant treatments
Anecdotal evidence
Pest resurgence even after high
application rates of soil fumigants
Or transition to sterile soilless media
Biological indication
Root systems are rapidly colonized by fungi
and bacteria after transplanting into treated soil
Colonization of pepper roots
30 days after transplanting
(Green Cay Farms, Delray Bch)
1999
2000
Ecologically based principals
Select species are well adapted for exploiting undisturbed sites
Diversity in newly colonized sites rapidly reaches equilibrium
Simberloff and Wilson, 1968.
Experimental zoogeography of islands:
the colonization of empty islands.
Ecology, 50: 278-296
Statistical reasoning
• 1 acre furrow slice ≈ 1 billion grams of soil
Each g of soil contains:
• 108 – 109 bacteria
• 107 – 108 actinomycetes
• 105 – 106 fungi
• 100 microsclerotia of Verticillium dahliae
Operational tenet - reapplication required
prior to the next planting cycle
A systems-based approach to
management of soilborne pests
• Indigenous biological communities limit
pest outbreaks through self-regulating,
feedback mechanisms.
• Interventive activities are supplemental
when needed
• ‘Ecological agriculture’ (Levins, 1990)
• ‘Total system approach’ (Lewis et al., 1997)
• ‘Proactive pest management’ (Sylvia & Chellemi, 1999)
Fundamental premise
• Responsible microorganisms occur
naturally in soil, regardless of prior land
management practices.
• Re-establishment is promoted through
substrate and plant mediated events
Naturally occurring pest
suppressive soils
•
•
•
•
•
Club root of cabbage (Plasmodiophora brassicae)
Fusarium wilt of watermelon (Fusarium oxysporum)
Sugar beet cyst nematode (Heterodera schachtii)
Potato scab (Streptomyces scabies)
Apple replant disease (complex includes
Cylindrocarpon destructans, Phytopththora
cactorum, Pythium spp. and Rhizoctonia solani)
• Take-all decline of wheat (Gaeumannomyces
graminis)
• Root-knot nematode (Meloidogyne incognita)
Organic soil management program
Cover crops and soil solarization
Annual application of urban plant debris
tons/acre) and broiler litter, (10 tons/acr
Survey of Fusarium oxysporum in an
organic farm with minimal Fusarium wilt
and a near by conventional farm with high
level of Fusarium wilt
Conventional farm
Organic farm
Number of isolates obtained
209
193
Pathogenic isolates
63 (30%)
3 (1.5%)
Bao et al., 2004. Biocontrol genotypes of Fusarium oxysporum
from tomato fields in Florida. Phytoparasitica 32:9-20.
Header Canal Project (2000 - 2004)
Years 4 and 5–cultivation of tomato
2003
DNA fragment lengths separated and detected
by electrophoresis in automated sequencer
ABI Prism® 310 Genetic Analyzer
ITS 1
ITS 2
559 586
Yeast (Saccharomyces cerevisiae)
bp
Fungal rDNA ITS-1 of July 2003
Transform: Square root
Resemblance: S17 Bray Curtis similarity
2D Stress: 0.18
ITS-1 End
of year 3
Treatments
Bahia
Conventional
Disk fallow
Organic
Weed fallow
Similarity
35
Fungal rDNA ITS-1 of Jan. 2005 S
Transform: Square root
Resemblance: S17 Bray Curtis similarity
End of tomato crop
Preceded by tomato in 2003,
land management 2000-2002
2D Stress: 0.13
Treatment
Bahia S
Conventional S
Disk fallow S
Organic S
Weed fallow S
Similarity
40
Identifying specific effects of transitional practices
Using microplots infested with Ralstonia solanacearum,
Meloidogyne incognita, and Cyperus rotundus
Interaction of urban plant debris and cropping
sequence on bacterial wilt of tomato
Interaction of broiler litter and cropping sequence
on the severity of root galling
Generate multiple revenue streams
from rotation crops
Use locally available recyclable resources,
realistic application rates, and
technically feasible application methods
Address issues related to urban encroachment and
proximity to environmentally sensitive areas
Solarization
Resistance/grafting
Crop rotation
Marketing & distribution
Farm operations
Individual field
Pest complex
Soil
microbial community
Soil quality
Organic
amendments
Erin Rosskopf
Tiehang Wu
Nancy Burelle
Thank you !