Drilling down on drift control

June 10, 2022 3:57 p.m.

Getting the most out of an herbicide application not only includes maximizing efficacy, but also minimizing damage caused by herbicides. Being aware of what can go wrong and how to avoid it can lead to effective, on-target herbicide applications and help growers have a successful growing season – without the distress and loss caused by applications gone awry. Let’s drill down on drift control in this blog.

What is drift?

Drift occurs during the herbicide application. It is the unintentional, off-target application of herbicides. This can lead to damage to surrounding crops as well as an ineffective herbicide application.

There are several factors that can lead to herbicide drift, including:

  • Severe Temperatures: Ideal temperatures for herbicide-use range from 65 degrees F to 85 degrees F.
  • High Wind Speeds: Herbicide labels specify optimal wind conditions for application. If a grower goes off-label, their risk of drift increases.
  • Small Droplet Size: Smaller droplets are more likely to be carried away by the wind than larger droplets. Herbicide labels will also specify optimal droplet size to decrease drift.

Herbicides are most effective when applied in high humidity and with wind speeds of about 10 mph or less. Ensure that the application nozzles are on the correct setting to produce optimal droplet size to minimize drift. The position and height of the boom are also listed on the herbicide label. With the boom being closer to the crops, the distance the droplets can travel is reduced.

Drift control agents


The use of drift control agents (DRAs) and deposition aids can help to reduce driftable fines while ensuring that droplets stay where they need to be. This results in improved kill, less herbicide loss and increased coverage. With drift control being a top priority in the agriculture industry, approved DRAs are required with the dicamba herbicide applications.

The tank mix and DRA regulations have changed the way new products are developed in the agriculture industry. While previously the focus was on reducing small droplets and creating more uniform droplet sizes, with the development of new chemistries and herbicide technology, the necessary standard today is to develop adjuvants and other DRAs that create the larger droplets necessary to reduce off-target drift.

Increasing droplet size

The smaller the droplet, the further it is likely to drift. This is compounded by wind speed, which may carry fine droplets an even greater distance. The chart below illustrates this concept under wind conditions of 3mph; however, while increasing droplet size solves the issue of drift, it can be detrimental to coverage and getting droplets to stay on the leaf’s surface. Droplets that are too large or too small may bounce of the leaf, shatter into smaller droplets or run off.

Optimize DRA use for the best results

Industry professionals agree the proper use of DRAs yield the best results. They also know there are many factors that can affect the efficacy of a pesticide application, including, but not limited to the DRA.

Today’s goals include minimizing off-target application, while trying to maximize the efficacy of the chemistry you are applying. This is why product manufacturers are working with industry experts and the EPA to come up with the best solutions for pesticide applicators and growers.

However, as you consider your crop protection recommendations for next season, keep in mind that there are factors beyond the tank mix that in cooperation with each other, can also affect off-target movement.

These other factors include:

  • Spray nozzle selection
  • Volume and pressure of sprayer
  • Environmental conditions
  • Pesticide tank mixes’ impact on droplet size

It is important to make sure you follow the application requirements for each product. The manufacturers have online resources that are updated regularly, and product labels are clearly marked with specifications and regulations for spraying conditions, boom height, mixing instructions and additional information. Be attentive to the label to ensure that you are using the products correctly and in turn, reducing the potential for off-target drift.

Proper use of DRAs with approved tank mix partners is important and helps avoid damage to crops in neighboring fields and other species. It will also allow the industry to continue using these herbicide technologies as part of an effective weed management plan.




Petrichor is a soy-enhanced drift and deposition agent unique to CHS. It offers enhanced performance, storage stability and mixability as a result of less impurities found in refined soybean oil. It reduces fine droplets and holds spray pattern in more uniform larger droplets at a low use rate of 3 oz/A.

Parachute II is another low use rate drift and deposition agent; however, it contains an additional mode of action that uses pine resin. This mode of action creates a thick, sticky structure that helps to increase droplet size and add weight to get down into the canopy and stick to the leaf surface. Parachute II is safe on corn at late vegetative stages, pre-tassle, so growers don’t have to worry about arrested ear.

For more information on drift control agents and how you can drill down on drift this season, talk to your local CHS Agronomy representative.