Small Volume Spray Solutions - Amount of Product per Multiple Gallons

Learn how to properly mix pesticide spray solutions when working with small areas using a backpack or hand-held sprayer. This tutorial walks you through the University of New Hampshire’s worksheet for label rates listed per multiple gallons (such as per 5, 10, or 100 gallons) and shows you how to scale them down for precise small-volume applications.

In this video, you’ll learn:
• How to calculate total spray solution needed for your area
• Converting label rates (per gallons) into amounts for smaller mixes
• Measuring product accurately in pounds and ounces
• Proper mixing techniques to ensure safe and effective applications
• Best practices for cleanup and record-keeping

Accurate mixing saves money, prevents waste, and ensures compliance with pesticide label requirements-while protecting both your crops and the environment.

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Using Backpack and Handheld Sprayers for Small Area Pesticide Applications
When applying pesticides to small areas, a backpack sprayer or handheld sprayer is often the most appropriate tool. These sprayers typically hold only a few gallons of spray solution, making them convenient and easy to maneuver in targeted spaces.
When preparing to mix pesticide products, you may notice that the label instructions are often based on larger application areas and higher volumes of spray solution than your task requires. To help with this, the University of New Hampshire has developed a series of worksheets that convert rates designed for large areas into equivalent rates for smaller applications.
Product labels vary in how they present mixing rates. You may see instructions based on:

Amount per gallon
Amount per acre
Amount per square feet
Or other formats

Choose the worksheet that matches the label rate format of the product you are using. Regardless of the format, you can mix your spray solution using a simple three-step process:

Determine the total spray solution needed.
Calculate the amount of product to mix into that solution.
Combine the product with the appropriate amount of water to prepare the final spray solution.

As with any pesticide application, recordkeeping is essential and required. It’s good practice to document the equipment used, application rates, and amounts for future reference.

Example: Using the “Per Gallons of Spray Solution” Worksheet
In this example, we’ll use the worksheet designed for products with label rates presented as an amount of product per multiple gallons of spray solution. These rates are commonly given per 10, 25, 50, or 100 gallons. This worksheet works for both liquid and dry products.
Let’s walk through the process using an example product with a label rate of 2 pounds of product per 50 gallons of spray solution.
Step 1: Determine Total Spray Solution Needed
First, calibrate your sprayer based on the label instructions and the terrain you’ll be spraying. UNH provides videos and worksheets to help with calibration.
In our example, we’re spraying a vegetable bed with a product that should be applied to the point of runoff. Calibration of our equipment tells us we’ll use 30 gallons of spray solution per acre to achieve this coverage.
Next, measure the area to be sprayed. Suppose the vegetable bed is 20 feet by 50 feet, totaling 1,000 square feet.
To calculate the spray solution needed:

Multiply the delivery rate (30 gallons/acre) by the area (1,000 sq ft)
Divide by the number of square feet in an acre (43,560)

(30 × 1,000) ÷ 43,560 = 0.69 gallons of total spray solution needed
Step 2: Calculate Product Amount
The label rate is 2 pounds per 50 gallons. First, convert this to pounds per gallon:
2 ÷ 50 = 0.04 pounds per gallon
Next, multiply this rate by the total spray solution needed:
0.04 × 0.69 = 0.028 pounds of product
To improve measurement accuracy, convert pounds to ounces. Since there are 16 ounces in a pound:
0.028 × 16 = 0.45 ounces of product
Step 3: Mix the Spray Solution
Weigh out 0.45 ounces of product. Add approximately half the total water volume to your spray tank, then add the product. Agitate the tank to mix thoroughly, then add the remaining water to reach 0.69 gallons of total spray solution.

Final Tips
Efficient and effective pesticide applications begin with a proper mix based on the label rate and the correct worksheet. Accurate calculations ensure you prepare just the right amount of spray, eliminating waste and leftover product.
After spraying, clean and store your sprayer and all measuring and mixing tools thoroughly.
For more information on best practices for backpack and handheld sprayer usage, visit the University of New Hampshire Extension website to view our instructional video programs.