The movement of turf pesticides to non-treated areas of a golf course can have potentially disastrous implications for non-targeted turf or ornamentals. Foliar or root injury to turf and other species that are sensitive to certain pesticides could result in plant death on highly desirable turf surfaces, such as putting greens, or damage to ornamentals in highly visible areas on the golf course.
With proper information on short-term weather conditions, knowing what is going on underneath your turf, paying close attention to and following pesticide labels, and proper timing of applications, pesticides will impact only the area that needs treatment and not damage adjacent turf or other plants.
“Application technology in the form of nozzles and GPS sprayers have improved the superintendent’s ability to place pesticide products where they want them,” says Kyle Miller, senior technical specialist for BASF Professional Turf and Ornamentals. He adds pesticide chemistry has improved formulations and lowered application rates to mitigate drift scenarios.
Yet, it still happens, says Cam Copley, golf/national accounts manager for Nufarm Americas. “Despite being very careful, pesticides can move off target through water movement, foot traffic or mechanical traffic,” Copley says. “It is more common than it should be, but the most common cause would be not allowing enough a reentry timeframe into the area.”
Off-target pesticide movement takes many forms depending on how sensitive the off-target species is and what type of rate was applied. Additionally, pesticide symptomology can be highly varied depending on the pesticide’s mode of action, says Dr. Jeff Atkinson, SePro’s portfolio leader, turf and landscape.
“In the case of a herbicide, off-target movement can range from transient phytotoxicity to total plant death,” Atkinson says.
When applied according to label directions, superintendents can limit unintentional or off-target movement of pesticides. However, accidents, unforeseen weather and other events can lead to unintentional effects, says Dr. Zac Reicher, technical specialist for the Bayer Green Solutions Team.
Most unintentional consequences typically occur during mixing or application. And most of these problems can be avoided by taking a little more time in preparation and getting a second set of eyes to check the calculations and products to be mixed, Reicher says. “This is easier said than done with the hectic golf course schedules, but extremely important given the cost of each application as well as the potential costs of a misapplication,” he adds.
Understanding the biological and chemical properties of a pesticide is the compliment to understanding the mode of action of a pesticide, Atkinson says. A pesticide’s ineffectiveness often results from the inability of the pesticide to reach the target, he says. Or in the case of an herbicide, the inability of the herbicide to penetrate the target’s cuticle to reach the active site within the plant.
“Understanding pesticide chemical properties will help an applicator decide if and what type of surfactant would improve efficacy and what other types of products the pesticide can be mixed with,” Atkinson says. “There’s a tremendous amount of information available on pesticide products today. Taking advantage of university extension programs is a great way to access this information. Within the last several years, university turf programs around the country have done a great job of improving the accessibility of information on their respective websites. Often, that’s a great place to start. Manufacturer and distribution technical specialists are also great resources for specific product information.”
Before applying product, superintendents and turf managers must understand pesticide volatility, water solubility, residual and other vital characteristics, Miller says.
“While these might all be desirable attributes in most situations, not being aware of these could result in unintended damage to desirable turf or ornamentals,” he adds. “It’s very important to attend your local university field day and find out for yourself what the experts are saying with regard to efficacy and overall use and performance of products in your geography. In addition, keep in touch with your fellow superintendents to find out what they are saying.”
Weather plays a critical role in pesticide efficacy and avoiding off-target intrusion, Copley says. For example, some products need to stay on the leaf for a certain amount of time, so a rain event will ruin that application. Some chemistries require a temperature range because at low temperatures the plant will not respond to the product, and at high temperatures the product can cause damage. Wind is also very important because windy conditions can result in products moving off the desired site, Copley adds.
Golf courses in regions that manage cool- and warm-season grasses adjacent to each other can be negatively affected by off-target movement of pesticides, says Dr. Travis Gannon, assistant professor pesticide/trace element fate and behavior at North Carolina State University.
“There are bentgrass greens even in places like Florida, so this can be a problem in a number of regions,” Gannon says. “Especially where there is a good deal of slope in the areas around the green complex, off-target pesticide movement can prove problematic.”
Gannon advises superintendents to understand soil moisture content when applying pesticides to prevent sub-surface, off-target flow. Also, they should pay close attention to short-range weather forecasts to avoid treating turf prior to thunderstorms or other large, impactful rain events that will lead to the unwanted movement of pesticides on the course.
In other words, know what will happen above the ground, what is going on below the turf, and then time pesticide applications accordingly, Gannon says.
Low-mowed greens are usually most susceptible to damage, and thus why many pesticides are prohibited from use on greens, Reicher says. “Young turf can be very susceptible to herbicides,” he adds. “Extra care should be taken on courses with warm-season grasses immediately adjacent to cool-season grasses since herbicides used on one can be damaging to the other.”
Annual bluegrass greens may be the most vulnerable to disease damage. This can be exacerbated by poorly drained soils, wet conditions, the growth habit of annual bluegrass and the multitude of diseases that attack an annual bluegrass plant. Annual bluegrass roots will typically grow near the soil surface during periods of summer stress. Because there are diseases that affect the foliage (dollar spot), crown (anthracnose) and roots (summer patch), pesticide applications need to account for what effect weather may have on fungicide efficacy.
“Areas that are heavily sloped are especially vulnerable as pesticide products can be moved off target, especially if the product is highly water soluble,” Miller says. “Thin turf areas are also vulnerable because there is little vegetation for the product to become adsorbed to.”
All grasses/areas are vulnerable if an applicator is careless, Atkinson says. Therefore, it’s better to approach it as everything is equally sensitive to an off-target pesticide application. This approach prevents an applicator from overlooking common application pitfalls that may result in off-target pesticide application, he adds.
Experts at regional universities, sales professionals, company representatives and other superintendents are all vital resources to learn what works best for an agronomic situation. “Also, the superintendent should do their own research about how that class of chemistry works and how the mode of action will respond when they make the application,” Copley says.