AGR 3102 Principles of Weed Science Herbicide

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AGR 3102Principles of Weed ScienceHerbicide

• Muhammad Saiful Ahmad Hamdani

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Unit 6 Topics Covered

• Herbicide Calculations
• a.i. (active ingredients)
• a.e. (acid equivalent)
• Calibration

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Herbicide Calculations

• 2 methods
• 1) active ingredients (a.i.)
• 2) acid equivalent (a.e.)
• 1) a.i. calculation
• - a.i. is always identified on the herbicide
  label.
• - often expressed as either a or in g/L.
• - calculations based on dry or liquid
  formulation.

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• Several calculations to determine the amount of
  a.i. applied. One of the easiest calculations
• g a.i. applied per ha
• kg or L of product applied X g active
  ingredient
• ha L or kg of product
• Example calculation of dry formulation
• - Herbicide Plantgard with 30 2,4-D (note 30
  w/w in trade
• formulation 30g a.i. in 100g product or 300g
  a.i. in 1kg product)
• - Spray recommendation 2.5kg product / ha
• - How much is the 2,4-D in the product when we
  apply
• 2.5kg of Plantgard per ha???

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• g a.i. applied per ha
• kg or L of product applied X g active
  ingredient
• ha L or kg of product
• 2.5kg Plantgard X 300g 2,4-D
• ha 1kg Plantgard
• Answer 750g a.i. 2,4-D per ha applied when
  spray at recommended rate of 2.5kg
  Plantgard per ha

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• Example calculation of liquid formulation
• - Herbicide Gramoxone with 35 paraquat (note
  35 w/v in
• trade formulation 35g a.i. in 100mL product or
  350g a.i. in 1L product)
• - Spray recommendation 3kg a.i. paraquat / ha
• - How much is the Gramoxone required when we
  apply
• 3kg a.i. paraquat per ha???
• g a.i. applied per ha
• kg or L of product applied X g active
  ingredient
• ha L or kg of product
• 3kg paraquat per ha ?L Gramoxone X 350g
  paraquat
• 
  ha 1L Gramoxone
• Answer 8.57L Gramoxone is required for 1ha when
  spray
• with 3kg a.i. paraquat per ha

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• 2) Acid Equivalent (a.e.) calculation
• Herbicides a.i. usually in parent acid form (its
  herbicidally active form), but many are
  formulated as a derivatives (i.e. esters, salts,
  amines).
• Alterations with herbicide molecules that are
  acids (at carboxyl COOH structure).

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• Why would a herbicide be formulated as a
  derivative (ester, salt, amine, etc.) of the
  parent acid?
• - Increase the ability of the herbicide
• to penetrate/absorb through the
• leaf/root much more effectively.
• - Increase the water solubility of the
• herbicide
• a.e. calculation indicates the amount of an acid
  herbicide in a formulation.
• Some labels indicate both a.i. and a.e. contained
  in the formulation, while others list only one or
  the other.

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• Sometimes, the numbers in formulation do not
  indicate gram active ingredient per L or kg, but
  rather the acid equivalent per L or kg.
• If the g a.e. is specified on the product label,
  to determine the g a.e applied per ha is
  substitute g a.e for g a.i. in the equation given
  previously.
• If not specified, calculate a.e. first using this
  equation
• acid equivalent () molecular weight of the
  acid 1 X 100
• molecular weight of the herbicide
• - molecular weight of the acid has to minus (-)
  1 because one H atom is missing when formed
  derivative (H was replaced by the
  salt/ester/amine i.e. NH4 / Na)

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• Example
• 2,4-D herbicides can be found in ester or amine
  formulation
• 2,4-D dietanolamine salt 326 mw
• 2,4-D acid (pure form) 221 mw
• of a.e. 2,4,-D 221-1 X 100 67.5
• 326
• If in a 2,4-D formulation contains 700g
  dietanolamine salt per L, the g per L a.e. 2,4-D
  in the formulation is
• 67.5 (a.e.) X 700g/L (2,4-D salt formulation)
  472.5g/L
• 100
• 472.5g is the actual a.i. 2,4-D (in a.e.) that
  cause phytotoxicity to plants/weeds

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• Now, how much g a.e. 2,4-D per ha is applied if
  the spray dosage recommendation is 5L product per
  ha?
• g a.e. applied per ha
• kg or L of product applied X g acid
  equivalent
• ha L or kg of
  product
• g a.i. applied per ha 5L X 472.5g
• ha L
• 2362.5g a.e. 2,4-D per ha is applied when
  sprayed at the
• recommended rate of 5L/ha product

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Calibration

• A technique to help you calculate how much water
  / chemical mix your sprayer puts out to ensure
  that the correct rate of chemical is applied to
  the target plant.
• 2 types of sprayer knapsack sprayer and
  boom-sprayer.
• Calibration will be emphasized on knapsack
  sprayer.

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Knapsack Sprayer Calibration

• 1) Measure the spray width of the nozzle(s) on a
  dry surface (in m).
• 2) Spray a test area at the intended pressure and
  walking pace. Record distance (in m) covered in
  one minute (min).
• 3) Measure the nozzle output in L over one min in
  a measuring jug (L/min). Repeat all steps at
  least twice.
• 4) The spray volume can be calculated by the
  following formula
• Application rate (L/ha) nozzle output
  (L/min) x 10,000 m2
• spray
  width (m) x walking speed (m/min)

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• For example
• Average nozzle output in 1 minute 3 L
• Spray width 1 m
• Average walking speed 100 m/min
• Application rate (L/ha) 3 x 10,000
• 1 x 100
• 30,000
• 100
• 300 L/ha application rate (water)

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• How much to put in a tank???
• The following formula can be used to determine
  the amount of product needed for each tank
• Product/tank (L or kg) recommended rate (L/ha
  or kg/ha) x tank size (L)
• application rate (L/ha)
• For example
• Recommended product dosage 5 L/ha
• Application rate 300 L/ha
• Spray tank size 20 L
• Calculation
• Product/tank (L/ha) 5 x 20
• 300
• Answer 0.33 L or 330 ml
• 330 ml of the product is added to a 20 L knapsack
  sprayer to give the recommended spray rate of 5
  L/ha.

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THANK YOU!!!!!