soybean seedling disease study
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Soybean seedling disease study. Funded by. Stand count is important. Reduced stands = reduced yield potential. The reduction in stand was achieved by random placement of 12-inch gaps within rows 2 to 4 weeks after planting ( Source: University of Illinois ). What affects stand establishment?. - PowerPoint PPT PresentationTRANSCRIPT
Soybean seedling disease study
Funded by
Stand count is importantReduced stands = reduced yield potential
Plant population (30-inch rows)
140k (8 plants/ft) 105k (6 plants/ft) 70k (4 plants/ft)
Stand reduction (%) Percent of yield potential
0 (full stand) 100 97 95
10 98 96 93
20 96 93 91
30 93 90 88
40 89 86 83
50 84 81 78
60 78 75 73
The reduction in stand was achieved by random placement of 12-inch gaps within rows 2 to 4 weeks after planting (Source: University of Illinois)
What affects stand establishment?
• Compaction• Flooding• Crusting• Seedling diseases• Planting depth• Cold stress
• Residue coverage• Sidewall compaction• Dry soils• Herbicide injury• Poor seed quality• Low germination
What affects stand establishment?
• Compaction• Flooding• Crusting• Seedling diseases• Planting depth• Cold stress
• Residue coverage• Sidewall compaction• Dry soils• Herbicide injury• Poor seed quality• Low germination
Seedling diseases
Phytophthorasojae
Pythium species
Rhizoctoniasolani
Fusariumspecies
Pre- and post-emergent ‘damping off’
Causal organisms:
Oomycetes vs fungi
OomycetesPhytophthora sojae,
Pythium species• Cell wall composed of
cellulose• No cross walls in hyphae• Diploid nuclei in vegetative
state• “Swimming” spores• More closely related to
brown algae and diatoms
True fungiFusarium species, Rhizoctonia solani
• Cell wall composed of chitin
• Cross walls in hyphae• Haploid nuclei in vegetative
state• Air- or splashed- dispersed
spores• More closely related to
animals
Oomycetes vs fungiOomycetes
Phytophthora sojae, Pythium species
True fungiFusarium species, Rhizoctonia solani
Conditions for disease development
Soil moisture Soil temperature
Pythium Flooded Cool (50-60 F)
Phytophthora Flooded Warm (70s F)
Fusarium Wet to dry Cool to warm
Rhizoctonia Damp to wet Warm (70-80s F)
Managing soybean seedling disease
1. Good seedbed conditions
2. Seed treatments• “What's on your seed?”
available fromhttp://ipcm.wisc.edu/
3. Resistance
Seed treatmentsActive
ingredientPhytophthora
sojaePythium species
Rhizoctonia solani
Fusarium species
mefenoxam/metalaxyl
E E N N
azoxystrobin - P F Ffludioxonil N N G Gipconazole - P F G
pyraclostrobin - P F Ftrifloxystrobin - P F F
E = excellent; G = good; F = fair; P = poor N = none
Survey of soybean seedling diseases
Isolates or soil received from 12 statesState No. of fields sampled No. of putative oomycete culturesArkansas 1 1001Illinois 6 219Indiana 5 401Iowa 9 394Kansas 7 250Michigan 12 276Minnesota 6 251Missouri * 6 0Nebraska 4 90North Dakota ** 6 225South Dakota *** 6 0Wisconsin 6 132Total 74 3239Average 6.2 270
*Soil samples collected, isolates will be baited; **Not including mid-season isolates; *** Isolates collected being purified
Oomycete species diversity
43 Pythium species2 Phytophthora species
Acknowledgements• Extension Network – Oomycete collections• NIFA funded 2011 to 2015• NCSRP and USB funding 2012 to 2014• MSU - Project GREEEN funded 2011