There is an old saying in lawn care that a client seldom fires a provider because the grass wasn’t green enough, but they will if the weeds aren’t kept in check…

With it becoming harder and harder to find good labor and cost increases all around, we are all challenged to do more with less. So, you may be wondering if premium broadleaf herbicide mixes are worth the extra cost. To help you decide which herbicides to choose and how to save money in the long run, let’s first learn more about the ingredients and how they work.

When we look at post-emergent broadleaf herbicides, we are really focusing on two main categories of products: Group 4 (the growth regulators) and Group 14 (the PPO inhibitors). There are a few additional chemistries, like mesotrione, from different groups, but I would like to focus on the two main groups that make up the lion’s share of what we use.

Group 4- Growth Regulators (Synthetic Auxins)

Synthetic auxins like 2,4-D were some of the first herbicides to be developed and used on a wide-scale basis. The synthetic auxins are all growth regulators that affect different growing mechanisms inside the plant. They continue to be the most important group of herbicides we have. Within the synthetic auxins, there are four main sub-types:

  1. Phenoxies (2,4-D, MCPP, MCPA): These mimic the plant growth hormone indoleacetic acid (IAA) and cause uncontrolled twisting, curling, and elongation, resulting in the weed growing to death.
  2. Benzoic Acid (Dicamba): Causes uncontrolled growth in the vascular system, preventing nutrient transport inside the weed.
  3. Pyridines (Triclopyr, Fluroxypyr, Clopyralid): Cause uncontrolled growth and blockage in the vascular system though through more complicated processes. The effect is similar to Dicamba.
  4. Quinoline Carboxylic Acid (Quinclorac): Causes death by increasing the production of ethylene in the weed. This is the same process that causes leaves to change color and drop in the fall.

The main route of absorption for the phenoxy herbicides is foliar, but the other three groups can be taken up through both the leaf and the root, which should help you to decide which products to use at different times of the year to improve results.

Group 14: The PPO Inhibitors

This group includes sulfentrazone, carfentrazone-ethyl, pyraflufen-ethyl, and flumioxazin. These are referred to as membrane disruptors, which means they basically break open cells and cause everything to leak out and die. They work very quickly but do not really move inside the plant, so by themselves, they don’t always cause death. They can burn a weed down within a day only to have it regenerate from the root shortly after. PPOs are often added to mixes for a fast visual response; but in a mix, they can also help the growth regulators get inside the plant easier providing a systemic kill.


When we look at all these different premium products on the market, we can now start to make a more informed decision on which product to use based on the time of year.


In the spring, the flow of substances inside the plant is primarily from the root to the leaves. It may be better to use a product like Nufarm Escalade 2 which has 2,4-D, Dicamba, and fluroxypyr. Even though these are growth regulators, they all have different modes of action inside the weed, and two of the three are root-absorbed. Also, it is beneficial to use herbicides with more soil activity to increase the likelihood that they will be taken up by the plant and do their job.


In the summer months when there isn’t as much movement in the weed up or down, using a mix that has multiple modes of action plus a PPO inhibitor like Armortech Tetra may work better. This is especially true when faced with more challenging weeds like thistle, clover, knotweed, purslane, violet, and ground ivy. PPOs help penetrate the thick waxy surface that weeds develop on their leaves to help them survive the hot, dry months and allows the other ingredients to get into the weed and seal the deal.


In the fall when the weed is taking everything down to the roots, a less expensive herbicide mix such as Armortech Threesome with two modes of action can be highly effective at killing the weed. However, the catch is the timing. With this product, late September into early October would appear to be the most opportune time to go after the weeds.

Preventing Resistance

When I look at recommendations for customers, I try to stick with products that have at least three unique modes of action. The more modes of action they have, the more weeds they kill. If you have used the same product on the same properties for many years in a row, you could be unintentionally making your life harder. This is because the product you have always used may not do a good job controlling things like clover, ground ivy, or violet. Over time these uncontrolled weeds can end up dominating a property.

The Importance of Surfactants

I also need to mention the equal significance of using surfactants. Except for herbicides containing PPOs, most products recommend the use of a surfactant. Surfactants help the herbicide to stick to the leaf surface instead of bouncing off and allows the leaves to stay wet longer so the herbicide can work its way into the weed. Besides reducing drift and volatilization, using a surfactant can help you target a large area of weeds without using more chemical than you had initially planned.

Using a pH Buffer

Many products contain phenoxies which are very sensitive to pH. The addition of a pH buffer will not only help keep these products from breaking down in the tank, but it will also help the herbicide break through the leaf surface too. Precision Laboratories Chem-Stik LpH will help with these issues and make a huge difference for only pennies.

The value proposition is that these products may cost a little more, but they are a bargain when compared to the costs of unnecessary service calls and lost customers. As we look for ways to increase profits and customer retention, reduce waste, and improve efficiency, it should go without saying that what you use should be a very important part of the conversation.

Be sure to contact your ATS representative to help with your plan for weed control!