Answers to Pesticide Calibration Problems
Problem 1. ��The label for Bug Rid 4EC says to apply 0.1 lb ai / 100 gal to control Japanese beetles.� How much bug rid do you need to put into a 5 gallon sprayer to control Japanese beetles in a bed of roses.�
1.� Determine the amount of active ingredient �x� you need to put into a 5 gallon sprayer.�
Here are two ways you can do this:� First the ��� more formal way:
a. Use the ratio from the label to determine �x�, or the lbs of active ingredient (ai) you need in the tank. .
x�� ai�� �=
0.1�� ai
5 gal� �����100 gal
Solve for x by cross multiplying
(0.1)* (5)=� (x)* 100
0.5��������� = 100x������
Divide both sides by 100 to get x
0.005�� � =� x
�
b.� A second way of looking at this is more intuitive.� Ask yourself what the relationship is between the volume of spray you will be mixing and the labeled rate;� Since you have a 5 gallon sprayer, you will choose to mix 5 gallons of finished spray.����
How much spray you mix��������� ������� = 5
gallons spray������������� �� =����
� ���������1�� = 0.05
The volume spray on the label rate =���� 100 gallons spray on label rate������� 20
In other words the amount of spray you will be mixing (5 gallons) is 1/20 of the 100 gallons indicated on the labeled rate.� To determine the amount of active ingredient you must multiply the labeled rate 0.1 by 0.05 to get 0.005.
2.� Now that you know you need 0.005 ai of Bug Rid in the tank to treat the property you must determine how much Bug Rid 4EC you need to put into the tank. This means that by convention that Bug Rid 4EC has 4 lbs ai in a gallon. ��To solve this in a formal way set this up as a ratio problem like before.
4 lbs ai ����=�� 0.005
ai
1 Gallon���������� y gallons
Cross multiply
(0.005) *1 = 4* y
0.005����� =� 4y
Divide both sides by 4 to determine the number of gallons of Bug Rid 4EC you need to put into the tank.�� Or 0.00125 gallons.
You can convert to teaspoons by multiplying by (128 oz/gal)* (6 tsp/oz)=0.096 tsp or about 1 teaspoon.
�
Problem
2.
The label for BugRid 10G says to apply 1 lb ai /1000 sq ft.� A. How much product do you need to treat a 75� by 50 � area of turf.
1.� Determine the total area to be treated by multiplying the length time width.
75X 50= 3750 square feet.
2.� Determine the amount of ai you need to apply to 3750 sq ft by setting up a ratio problem with x = the ai you need.
1 lb ai�� � ��������� =� x�����
1000 sq ft ������� �����3750 sq ft of lawn
Cross multiply
1000x=3750
������� x= 3.75 lb ai
Since Bug Rid 10G is a granule that contains 10% ai by weight, determine what you need to buy by setting up another ratio with y = the amount you need to buy.
1 lb ai��� ���������� =� 3.75 lb ai
10 lb Bug Rid�� ��� y
Cross multiply to determine y��� , the amount you need to buy.
Y= 37.5 lb Bug Rid.� You need� to buy 10 lbs to get the 37.5 lbs that you need. �
2.�� How fast should you go if you deliver 0.1 lb of product per minute across a 4 ft swath?
The 0.1 lb product per minute means that 0.1 lb is being delivered through the application device.��
To determine how fast you should go to deliver 1 lb in 1000 sq ft, first determine how far you must drive to cover 1000 sq ft.��� If your application device delivers product across a 4 ft swath, you need to drive 250 ft to cover 1000 sq ft.
Because Bug Rid 10G a contains 10% active ingredient you need to apply 10 lbs of product to deliver 1 lb of active ingredient to the 1000 square ft area you cover when you drive 250 ft.�
If your device delivers 0.1 lb product per minute it will take you 100 minutes to deliver 10 lbs.� This means you�d have to go 2.5 ft per minute to cover the 250 linear feet in 100 minute.
Now let�s be realistic, most people would probably fall
asleep if they had to drive that slowly.�
In practice you�d probably set the rate of delivery a bit higher so you
could go at a comfortable pace, of 400 ft per minute, or 4.5 miles per
hour.� Since this is 160 times faster
than the 2.5 ft per minute, your delivery rate would be set to 16 lb/minute.