March 28, 2008

We would like to remind our readers about the availability of a free online tank-mix calculator from WeedSOFT (http://weedsoft.unl.edu/). The tank-mix calculator is useful for commodity producers, custom applicators, and others applying herbicides. The calculator generates a printed load ticket that gives precise amounts of herbicide(s) and adjuvants (general list) to add to the spray tank. The load ticket can also functions as a record-keeping tool. Below we review how to use the calculator.

Using the UNL Tank-mix Calculator

The calculator can be reached from the WeedSOFT home page (http://weedsoft.unl.edu/). It is located under the "Tools" menu (see Figure 1). Move the cursor over "Tools," then click on "Calculators."

Figure 1. Locate the calendar on the WeedSOFT home page under "Tools."

Figure 2 shows the calculator page of WeedSOFT. A second tool is the WeedSOFT Yield Loss Calculator. (We will address its functions in a future CropWatch article.) To access the Tank Mix Calculator, click on the sprayer, and then on the following screen click on "Continue to Calculator."

Figure 2. WeedSoft page showing two tool options.

Figure 3: Screen shot of the online WeedSOFT Tank-mix Calculator information input page.

1. Field size
2. Sprayer tank size
3. Carrier volume or intended sprayer output (gallons per acre)
4. Herbicide name
5. Herbicide bulk unit (what form and volume is the herbicide packaged in)
6. Herbicide rate
7. If multiple herbicides are to be added to a tank-mixture, click on the "Add Herbicide" button, then repeat steps 1-6 for the next herbicide, otherwise, move to step 8.
8. This gives you the option of mixing the same volume of spray in your tank for each trip (if multiple trips are required), or to prepare all but the last load to the maximum capacity of your spray tank.
9. Click on the "Calculate" button when you have entered the above information to generate the load ticket.

The load ticket (Figure 4) includes the information the user entered for field size, tank-size, carrier volume, herbicides and herbicide rate. In addition, it provides the EPA registration number for each herbicide. If the user selected the option to have full loads and a final partial load, the amount of each herbicide to add to each full load and the partial load is listed in Box 1. Print the screen to obtain a paper copy.

The form provides space (Box 2) for the applicator to list critical information after application, such as location, wind speed and direction, temperature, crop stage, time of application, etc. This then becomes a valuable record-keeping tool for regulatory and operation history purposes.

Figure 4: Example load ticket.

We believe the tank-mix calculator can be used to improve communication between managers and applicators, to reduce the misapplication of herbicides due to tank-mix calculation errors, and to facilitate improved record keeping.

Lowell Sandell
Extension Educator, Weed Science
Mark Bernards
Extension Weeds Specialist