Our Guide to Residual Herbicides

What is a residual herbicide?

A residual herbicide, also known as a long-lasting weed killer, is a type of herbicide that gives longer-lasting weed control of germinating. Residual weed control can be used in a range of different areas and, under the right conditions, can help keep weeds away for many months or even be longer depending on different conditions. For example, factors like the active ingredient used, weather conditions, soil type and the weed species can change the length of time a weed is kept away for.

At Nomix, our Nomix Dual residual herbicide keeps weeds away for between 4 to 6 months, depending on different factors. The main advantage is that you can use it in hard surface areas, for example, on streets or on roads.

How do residual herbicides work?

Residual herbicides, like Nomix Dual, need the active ingredient to be dispersed in the top layer of the soil, which is aided by soil moisture. The active ingredient is then taken up by the germinating weed. Once they have been applied, residual herbicides create a barrier layer in the soil that reduces weed growth for several months.

Residual herbicides contain an active ingredient that has pre-emergence efficacy; however they are often used alongside a post-emergence active, like glyphosate. This allows the user to control actively growing weeds, but also to control subsequent regrowth. Nomix Dual contains both a residual active ingredient and glyphosate, which is designed to control weeds, which means Nomix Dual is ideal for preventing and controlling subsequent growth of weeds. In most cases, where the residual active has worked, you will never see a plant emerge.

What are the benefits of residual herbicides?

One of the main benefits of using residual herbicides like Nomix Dual is that they have a residual active ingredient and contain glyphostate. With Nomix Dual containing glyphosate, once it is sprayed on the plant, the plant dies. The residual herbicide then prevents new growth from newly germinating seeds in the seed bed. Regrowth will come from existing or new seeds/spores in the soil, but the residual herbicide should reduce growth from for several months. The length of effectiveness depends on the product used and different environmental conditions.

Different weed species are more susceptible to chemicals than others and therefore some are easier to kill. Weather conditions and the type of product used do also affect efficiency. Residual herbicides are effective at the point of germination – meaning they stop the weed from ever emerging.

What can affect the performance of residual herbicides?

Several different things can affect how effective a residual herbicide is. These include:

• Water hardness – Where you are sourcing your water supply can affect how well a herbicide performs. One of the main benefits of using Nomix Dual is that it is premixed and requires no water.
• Rainfall frequency and intensity – Heavy rainfall can reduce the efficiency of a herbicide by causing it to move away (leach) from weed germination zones. Also, if there is an extreme lack of rainfall, for example a drought, it will have a negative impact, as the residual active can break down more quickly.
• Soil type – Herbicides leach quicker through coarse-textured (sandy) soils and fine-textured (clay) soils.
• Sun UV Light – Some residual herbicide products can be broken down by the sun’s UV rays, known as photolysis. This reduces the concentration and, therefore, the effectiveness of the herbicide.
• Poor application – If residual herbicides are not applied correctly, then the herbicides won’t be effective. This is why choosing the right application system is important.

How Total Droplet Control can help improve your residual herbicide application?

Choosing the type of residual herbicide and applicator is key. Nomix Total Droplet Control (TDC) is a herbicide application system that combines pre-mixed, highly effective herbicides with easy-to-use, targeted applications.

Using Nomix Dual can reduce the need for spraying, which will help save costs while keeping areas looking tidier while massively reducing your glyphosate usage which means less use of chemicals overall.

Nomix Dual is the only residual herbicide that is approved for use on both hard and soft surfaces in amenity areas. It can be applied to visible weeds and areas of potential weed growth, including on areas like the pavement edge, kerbs, gulley, around paving stones, gaps/cracks in the pavement and around obstacles. For soft surfaces, Nomix Dual can be applied to any natural surface that is not intended to bear vegetation, permeable surfaces overlying soil and around amenity vegetation, including shrub beds, tree bases and gravelled areas.