Peanut Field Spread of Aspergillus flavus and Aflatoxin Contamination

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breed [peanuts peanut]
breed [spores spore]
patches-own [soil-infected?]
peanuts-own [plant-infected? pod-count kernel-count kernel-af]

to setup
  clear-all
  setup-soil
  setup-spores

  reset-ticks
end 

to setup-soil
  ask patches [ set pcolor brown set soil-infected? FALSE]

  ;make a square field of peanut plants
  ask patches with [ abs pxcor < 13 and abs pycor < 13 ]
    [sprout-peanuts 1 [ set shape "peanut_plant"  set size .25 set pod-count  0 set kernel-af 0] ;setting up our peanut plants. Note that each plants has no pods at the beginning
  ]
end 

to setup-spores ;here each patch can be infected or not. We color it orange.
  ask n-of (infected_patches * (32 ^ 2) / 100) patches [sprout-spores 1 [set shape "aspergillus" set size 0.5 set pcolor orange]]
end 

to go
  ask peanuts [set size size + 0.005] ;allow our peanut plants to grow each tick, which represent 1 day
  infect-patches; spores infect the soil
  infect-from-patches ; the soil infects the peanut plants
  move-spores
  add_pods ;as peanuts grow, they produce pods in the soil
  infect_kernels ;kernels become infected when a plant is infected and and it's vulnerable due to environmental stress

  if ticks >= Season_length [ stop ] ; assume peanut harvest after 9-120 days
  tick
end 

to move-spores
  ask spores [
    right random 360
    forward 0.1
  ]
end 

to infect-patches
  ask patches with [ any? spores-here]
    [set pcolor orange]
end 

to infect-from-patches
; note that infection of plants is a stochastic process. However, the probability depends partly on whether pesticides are used to prevent plant disease and other pests in the first place
  ask peanuts [
    ifelse (pcolor = orange) and (pesticide-use = false) and (random 100 < 50) ;we assume plant infection is more likely if pesticides are not used.
    [
      set shape "peanut_plant_infected"
      set plant-infected?  true

    ]
    [
    if (pcolor = orange) and (pesticide-use = true) and (random 100 < 5)
      [
        set shape "peanut_plant_infected"
        set plant-infected?  true
      ]

    ]]
end 

to add_pods ;we add pods based on how many days we are into the growing season. The pods start to develop at day forty
  ask peanuts[
  (ifelse
    ticks < 40
    [set pod-count 0]
    ticks = 40
    [set pod-count 10]
    ticks mod 5 = 0
      [
        if heat-stress = true [set pod-count pod-count + 1]   ;water stressed plants will add pods more slowly
        if heat-stress = false [set pod-count pod-count + 2]
      ]
   )


               ]
  ask peanuts [set kernel-count pod-count * 2]
end 

to infect_kernels ;infection of peanut kernels depends on both use of water stress of the the plant and pesticide use. With more water stress, plants produce fewer phytolexins
                  ;and other defenses against aflatoxigenic fungi
  ask peanuts[
  if plant-infected? = true[
    (ifelse
      (heat-stress = false) and (pesticide-use = true)
      [set kernel-af 1 ]

       (heat-stress = false) and (pesticide-use = false)
      [set kernel-af  20  ]

      (heat-stress = true) and (pesticide-use = true)
      [set kernel-af 50 ]

      (heat-stress = true) and (pesticide-use = false)
      [set kernel-af 100 ]
  )]]
end 

There are 2 versions of this model.

Uploaded by When Description Download
Jeremy Schwartzbord 12 months ago Updated information section Download this version
Jeremy Schwartzbord 12 months ago Initial upload Download this version

Attached files

File Type Description Last updated
Peanut Field Spread of Aspergillus flavus and Aflatoxin Contamination.png preview Preview for 'Peanut Field Spread of Aspergillus flavus and Aflatoxin Contamination' 12 months ago, by Jeremy Schwartzbord Download

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