Threshold vs' adjusted dosage Svend Christensen and Torben Heisel, DIAS Mark Paice SRI

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Threshold vs. adjusted dosageSvend Christensen
and Torben Heisel, DIASMark Paice SRI
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Blackgrass (Alopercurus myosuroides)
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Old Seed Bank
Herbicide - use
Stochastic Weed Control
Stochastic Seed Mortality
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Initial Blackgrass Data

• Blackgrass density was measured in a 14 m x 14 m
  grid in a winter barley at Silsoe Research
  Institute
• The model unit was 1 m by 1 m cells
• Treatment unit was 4 m by 4 m cells

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Spatial weed management of Blackgrass

• The threshold algorithm
• PC-Plant Protection
• DAPS (Decision Algorithm for Patch Spraying)

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The Threshold Algorithm
If Blackgrass density was higher than 1 plant m-2
A normal dose of 3.5 l ha-1 IPU was applied
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PC-Plant Protection
A normal dose of 2.1l ha-1 IPU was applied
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DAPS - Decision Algorithm for Patch Spraying
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ResultsSeed Bank
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Seeds/m2
Year 0
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The Threshold Algorithm
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PC-Plant Protection
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Decision algorithm for Patch Spraying
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Yield loss (DKK ha-1)
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IPU dose (l ha-1)
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Cost (DKK ha-1)
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Model Assumptions

• The size of the treatment area affects the
  differences between the algorithm
• No spatially or temporally depended effect of
  soil conditions or cultivation factors on seed
  emergence, crop weed competition or seed
  production