IRVM: Herbicide Application

Through the years Mahaska County has advanced by leaps and bounds with its herbicide applications. Since the programs inception in 1998, we have progressed from hanging off the back of 1972 straight truck with a hand wand, to an in-cab controlled, injection spray system with GPS data collection.

With funding support from the Living Roadway Trust Fund, Mahaska County was able to upgrade our tank mixing spray system to an injection system. This allows us to carry three concentrated chemicals on board. Now with the flip of a switch we can use one, two, or all three chemicals depending on our target species. These are dosed out on an "as needed" basis according to how fast we are travelling and which boom nozzle we have turned on. This gives us a lot more efficient use of our chemical and is much more environmentally friendly.

GPS is also part of the system. With this system we have every application plotted on a real-time map which records our quantities used, time, and location of application. We can use this data to develop trends and what chemicals are working on different species.

Our chemical strategies have also changed. Gone are the days of using blanket spraying straight 2,4-D. Now we spot spraying using much more specialized and low use rate chemicals that have a lot less likelihood of moving to off-target areas. We are getting much better control on brush and weed species than ever before.

Each year we travel every county road controlling brush and weed species. We spray the county in quarters. Every year we start with a different quarter and rotate our starting point so we start in a different quarter every 4 years.

Intelligent herbicide application is a large part of the Integrated Roadside Vegetation Management approach. However, it is not the largest, or most important. We do it to control noxious weeds and brush in county right-of-ways and when used properly, it is very successful.