AGR 3102 (1)AGR 3102 (1)Principles of Weed SciencePrinciples of Weed Science

HerbicideHerbicide

Muhammad Saiful Ahmad HamdaniMuhammad Saiful Ahmad Hamdani

Week 12 – Topics CoveredWeek 12 – Topics Covered

Critical Factors Influenced Spraying

Herbicide Calculations

Critical Factors Influenced Spraying Process

• Product label spray condition recommendation (MANDATORY)

• Wind speed and wind direction

• Temperature & relative humidity (both soil and air)

• Sprayer height & speed (depending on spray quality)

• Local weather condition

If you can’t measure the conditions at the site of application, you can’t make an informed decision about when to change setup or when to stop

•Monitor and record conditions at least every load.

•More often at night ...if the wind stops, STOP spraying

Photograph by Graham Betts

What are suitable wind speeds?

• The maximum wind speed should not be above 20 km/h and preferably around 15 km/h….

• Higher wind speed can be managed when we have a canopy to catch the droplets.

Products/formulations: active ingredient (a.i.) + a series of “inert ingredients”.

Spray recommendations come as either product/area or as a.i. per area.

Herbicide CalculationsHerbicide Calculations

Pure form

• Some herbicides, trade name is followed by a number and letter designation.

• The number indicates how many g of a.i. are in a L (for liquid formulations) or g (for dry formulations) of the formulated product.

• Examples:

Herbicide Calculations cont…Herbicide Calculations cont…

First Thing To Do Before Calculating First Thing To Do Before Calculating Herbicide Amount Required For An AreaHerbicide Amount Required For An Area

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.

Herbicide Calculations cont…Herbicide Calculations cont…

• 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 per ha X g active ingredient per L or kg of

product

Product/tank (L or kg) = product recommended rate/ha X tank size (L) application rate (L/ha)

• 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???

g a.i. applied per ha =

kg or L of product applied per ha X g active ingredient per L or kg of product

g a.i. applied per ha =

2.5kg Plantgard/ha X 300g a.i. 2,4-D/kg

Answer = 750g a.i. 2,4-D per ha applied when spray at recommended rate of 2.5kg Plantgard per ha

• 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 per ha X g active ingredient per L or kg of product

3000g paraquat per ha = ҳL Gramoxone/ha X 350g a.i. paraquat/L

Answer = 8.57L Gramoxone is required for 1ha when spray with 3kg a.i. paraquat per ha

Exercise 1: Refer to your herbicide label

• Calculate how much is the a.i. actually applied per ha when the product is sprayed at the rate as recommended?

• How much is the product required for a knapsack sprayer with spray capacity of 20 L

• The number of spray needed to spray 1 ha area when use a 20 L knapsack sprayer

Exercise 2

• Lasso 500EC (a.i. alachlor) recommends to spray 30mL Lasso for every 5L water.

• 1ha area required 450L water.• Calculate:

a. How much Lasso is required per ha?

b. How much g a.i. alachlor is applied when spray at recommended rate per ha?

a. Lasso required per ha:

Recommended rate: 30mL Lasso = 5L water (1 ha required 450L water)ҳmL Lasso = 450L water (1ha)= 30mL Lasso X 450L water 5L water

Answer = 2700mL (2.7L) Lasso is required per ha for a recommended rate

b. g a.i. alachlor applied per ha when spray at recommended rate:

kg or L of product applied per ha X g active ingredient per kg or L product

2.7L Lasso/ha X 500g a.i. alachlor/L

Answer = 1350g a.i. alachlor per ha applied when spray at recommended rate of 2.7L Lasso per ha

Exercise 3

• Herbicide KillDaWeed contains butachlor granules (15% a.i.) with the application rate of 2 kg a.i./ha. How much (kg) is the KillDaWeed required to treat a 50m2 with rate as recommended by the label?

• Herbicide Cleansweep contains glyphosate (36% a.i.). How much glyphosate is required to treat a 2000m2 plot at the rate of 3.0 L Cleansweep/ha?

THANK YOU!!!!!THANK YOU!!!!!