Volatility Vs Drift: Know the Difference

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Innovations in chemical formulation have given vegetation managers a wide range of highly effective herbicides to choose from when setting their vegetation management (VM) strategies. Precision selectivity allows VM professionals to target specific weed and brush species at lower use rates and with fewer applications than ever before. But understanding two inescapable concepts — chemical volatility and chemical drift — can help vegetation managers and contractors reduce the risk of off-target movement and unintended damage to nontarget species while maximizing the effectiveness of every application.

Chemical Volatility

The volatility of a given chemical simply refers to how easily it changes from a liquid into a vapor. Volatility is influenced by a number of factors, including temperature, humidity and the properties of the herbicide itself. The higher the volatility, for example, the faster the chemical can evaporate, especially in hot weather.

For vegetation managers, knowing the volatility of their chosen herbicide and understanding the potential effects are critical. Using a highly volatile product near a residential or agricultural area can risk off-target movement of the herbicide onto neighboring plants or crops, while choosing lower-volatility herbicides, like Freelexx^® or Vastlan^®herbicides, can reduce the risk of damage due to unintended movement.

Drift

Whereas volatility is an indicator of how quickly and easily a chemical changes from a liquid to a gas, drift is all about the herbicide droplets moving through the air from the sprayer to the vegetation. Drift can happen during herbicide application due to wind, temperature changes or even equipment choice.

Drift can be particularly tricky to manage in populated areas where there are homes, parks and bodies of water close to the application area. To minimize the risk of unintended herbicide drift, vegetation managers and contractors can use a number of different tools, including low-drift spray nozzles or drift-control spray adjuvants. In addition, the risk of drift can be reduced by choosing calm, low- or no-wind days for spraying and by creating buffer zones — areas left untreated between the application site and nearby sensitive environments.

Key Implications

While volatility and drift work in different ways, both can result in off-target herbicide movement and unwanted exposure. Vegetation managers, therefore, should take both factors into account when choosing the product, location and timing for a given spray application. Use lower-volatility herbicides for those summertime applications, for example, and spray when winds are calmer. Watch for signs of temperature inversions, especially early in the morning or late in the day; low-lying fog, wind speed of 3 mph or less, and temperatures within 5 degrees of the overnight low are all warning signs.

Understanding the differences between chemical volatility and drift is essential for vegetation managers and applicators, especially those operating in or near populated areas. With a solid working knowledge of both concepts, VM professionals can make smart decisions that promote effective vegetation control while minimizing the risk of unintended herbicide movement into surrounding communities and environments.

Interested in learning more? Reach out to your local Corteva Agriscience Vegetation Management Specialist.

Freelexx^® and Vastlan^® are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions.