Unit 10. Calculating the Correct Amount to Apply Flashcards
What are your two (2) options for measuring out dry pesticide formulations?
- Use an accurate scale that can measure both pounds and ounces.
- Use the measuring device that came with the pesticide formulation (most commonly, for dry flowables (DF) and water-dispersible granules (WDG)). Note that different products and even different batches of the same product, may vary in density. Therefore, you MUST use the measuring device that was sold with the package.
When measuring liquid formulations, which is more accurate: a tall, thin graduated cylinder or a short, wide measuring cup of the same capacity? Explain your answer.
The graduated cylinder is more accurate because it will have more indicator marks on it than a measuring cup will.
List two (2) ways to measure the capacity of your spray tank.
- Fill the tank by hand using a container of known capacity (ex. a 5 gallon bucket that you have carefully filled to 5 gallons and marked).
- Attach a flow meter to a hose and measure the amount of water as it flows into the tank.
How do you know how much pesticide to apply?
Read the directions-for-use section of the pesticide label.
Some labels have charts that list a range of application rates. When you are unsure of the best rate to use, check with your pesticide dealer, extension agent or other university specialist.
List five (5) ways in which a product label might state application rates.
- Amount of active ingredient (a.i.) per unit area or volume (ex. 1 lb. of active ingredient per acre).
- Amount of active ingredient (a.i.) per volume of finished spray (ex. 2 lbs. of active ingredient per 100 gallons of finished spray mix).
- Amount of formulated product per unit area or space (ex. 5 gallons of emulsifiable concentrate per acre).
- Amount of formulated product per volume of mixture (ex. 1 pint of product per 1,000 square feet, applied in 1 to 2 gallons of finished spray.
- Percentage of the final dilution (ex. 0.5% by volume).
How do you know when you must calibrate application equipment?
When the label directs you to apply a specified amount per unit area (or volume).
Examples:
* 2 pints of liquid concentrate in 1 - 2 gallons of finished spray mix per 1,000 ft2.
* 200 lbs of granular product per acre.
* 5 lbs of active ingredient (a.i.) per acre.
Give an example of label directions that require mixing but no calibration.
“For hard-to-control perennial weeds, apply a 2% solution to foliage, with complete and uniform coverage.”
What types of formulations might need calibration and loading but no mixing?
Ready-to-use (RTU) formulations with label directions that require calibration. This would include …
* most granular and dust formulations
* some liquid formulations (for example, dilute end-use solutions)
* certain fumigants
What pesticide formulations must be diluted before application?
All but ready-to-use (RTU) products or those designed to be applied full-strength (ex. fumigants or products applied with ultra low volume equipment).
What information do you need from the pesticide label before you can dilute the pesticide correctly?
- What diluent to use (ex. water or light oil).
- How much to dilute the formulation.
- The application rate of the dilute pesticide.
What information about your equipment and the application site do you need in order to calculate how much pesticide and diluent to combine in your application equipment?
- How much your spray tank holds when full.
- How big the treatment area is.
- How much mixture your equipment applies per unit area.
- How much mixture you will need to complete the job.
How do you calculate the area of a square or a rectangle?
When calculating the are of a rectangle …
- Measure along the long side.
- Measure along the short side.
- Multiply the long side by the short side to obtain square feet (i.e. feet x feet = feet2.
When calculating the area of a square just square the length of one side. That is, multiply the length of one side by itself (side x side) to obtain feet2.
How do you calculate the area of a circle?
The area of a circle is calculated as “pi” x r2, where “r” is the radius of the circle x itself (i.e. r x r). This equation is commonly written as …
Area = π r2
The quantity “pi” or π is a constant = approximately 3.14. So if you had a circle of radius 25 feet, the area of the circle would be …
3.14 x 25 ft x 25 ft = 1,962.5 ft2
How do you calculate the area of a triangle?
Multiply the base (the length of the longest side), by the height (the width at the widest point) and divide by 2.
Area = base x height ÷ 2
How do you calculate the area of an irregularly-shaped site?
There are three (3) ways:
1. Convert the site into a combination of rectangles, circles, and triangles. Calculate the area of each shape and add them together.
2. If the site is roughly rectangular, use the transect method.
»_space; Establish a line down the middle of the site for the length.
»_space; Measure from side-to-side at several points along this line.
»_space; Average side-to-side measurements and use that number as width.
»_space; Multiply length x width.
3. If the site is close to round, treat it as a circle.
»_space; From the center, measure the distance to the edge in 10 places.
»_space; Average the 10 measurements to find the radius.
»_space; Calculate the area using the formula for a circle.
