When it comes to ordering and applying pesticides or herbicides, and ensuring you have the right amount of products per the recommended rates, start with a little math homework.
It takes a few simple calculations to avoid the frustration of being short of finishing an application, or storing large amounts of carry-over chemicals.
Once you’ve identified the number of acres to be treated along with the active ingredients and products you intend to purchase, a few calculations will reveal total amount of product required to complete the job.
Farmer Smith and his agronomist have decided that 625 acres of corn will be treated with:
Additives required by label are:
- Non-ionic surfactant or NIS-EA™ 1 quart (.25 percent volume per 100 gallons)
- Spray-grade ammonium sulfate or AMS-ALL™ 17 lbs. per 100 gallon carrier (2 percent volume per 100 gallons)
He intends to apply with 10-gallon-per-acre carrier with a ground sprayer.
What quantities of each product does he need to order?
Here is some example tank mix math involved.
- 625 acres X 3 qt. Lexar® = 1,875 quarts (4qts = 1 gallon)
- 1,875 quarts / 4 = 468.75 gallons Lexar® required.
- 625 acres X 1 qt. Roundup® Original = 625 quarts (4qts = 1 gallon)
- 625 quarts / 4 = 156.25 gallon Roundup® Original required.
- 625 acres X 10 gallon = 6,250 gallons to be sprayed.
6,250 gallons / 100 gallon = 62.5 units
- 62.5 X NIS-EA™ 1qt. = 62.5 qts. NIS-EA™
62.5 qts. / 4 = 15.625 gallons of NIS-EA™ required
- 62.5 X 17 lbs. AMS-ALL™ = 1,062.5 lbs. AMS-ALL™ required
When tank mixing pesticides or herbicides and additives, more math may be needed to ensure you follow label use instructions accurately.
If more than the recommended rates are applied, you’ll be off label and crop injury may occur and you may be subject to fines and more. If less than recommended rates are applied, you could experience unacceptable control over the pressure you're facing. Both of these scenarios can have a negative impact on crop yield and your operation.
Farmer Smith has a ground sprayer with tank of 1,200 gallon capacity. How much of each tank mix ingredient should be added to a tank fill?
- 120 acres X Lexar® 3 qt. = 360 qts. Lexar®
360 qts. Lexar® / 4qts = 90 gallon Lexar® per fill.
- 1,200 gallon tank / 10 gallon per acre application = 120 acres per tank fill
- 625 acres / 120 acres per tank fill = 5.20 tank fills
- 120 acres X Roundup® Original 1 qt. = 120 qts Roundup® Original
- 120 qts Roundup® Original / 4 qts. = 30 gallon Roundup® Original per fill
- 1,200 gallon tank / 100 gallon carrier = 12 units
- 12 X NIS-EA™ 1qt. + 12 qts. NIS-EA™
- 12 quarts NIS-EA™ / 4 qt. = 3 gallon NIS-EA™ per fill
- 12 X 17 lbs. AMS = 204 lbs. AMS-ALL™
- 204 lbs. AMS-ALL™ / 51 lb. bag AMS-ALL™ = 4 bags AMS per fill
5 full tank fills and last tank fill 20%, or 240 gallon with 20% each tank mix ingredient.
20% or 240-gallon tank mix needs as follows:
- 90 gallons Lexar® X 20% = 18 gallon Lexar®
- 3 gallons NIS-EA™ X 20% = .6 gallon or 2.4 quarts NIS-EA™
- 204 lbs. AMS-ALL™ X 20% = 40.8 lbs. AMS-ALL™
All of these calculations are basic math and can be done on a calculator. And similar math can be used for fungicides and insecticide applications.
Doing the math ahead of time will help to ensure that your pesticide order is efficient and addresses control of your targeted pests.
Remember to consult with an agronomist to ensure you are reading and following label use instructions properly.
- The difference between branded and generic ag chemicals
- What to consider when choosing between premix vs tank mix
*Always read and follow label use instructions, including permitted and non-permitted tank mixes. Examples are illustrative only and does not constitute a recommendation.
Sources and Labels:
Lexar® is a registered trademark of a Syngenta Group Company. AMS-ALL™ is a trademark of Drexel Chemical Company. NIS-EA™ is a trademark of Wilbur-Ellis Company. Roundup® Original is a registered trademark of Monsanto Technology LLC.