Herbicidal Tendencies

When Ben Franklin quipped that the only certainties in life were death and taxes, he obviously hadn’t asked any lawn care operators (LCOs) their opinions. In all likelihood, most LCOs would add one more grievance to their lists: weeds – especially crabgrass.

But unlike with Franklin’s complaints, LCOs have the ability to prevent weeds from becoming lifelong nuisances for their clients. Though a few weeds are expected in every lawn, preemergence herbicides can keep the majority of pesky species like crabgrass and goosegrass from making appearances during the growing season. And while preemergence products can be the priciest materials in an LCO’s weed control arsenal, when used properly, they reduce customer callbacks by significantly diminishing certain weeds.

PREEMERGENT POWER. "In and of itself, a weed isn’t bad," comments Scott Eicher, senior product manager, Dow AgroSciences Turf & Ornamental, Indianapolis, Ind. "But in a home lawn situation, during the course of a year, the weeds compete for water and nutrients and choke out the desirable turf. With preemergence herbicides, you can eliminate that problem before you see it. That means the homeowner never has to look at an ugly lawn and reinforces that the lawn care operator is a professional who can solve problems before they start."

By definition, preemergence applications create a herbicide barrier that poisons weeds before germination, thus preventing the weeds from infesting lawns. Of all the lawn problems LCOs address, most report that crabgrass tops their lists of customer complaints, making preemergents lawn care necessities.

"Most of our customers expect to receive an application for preemergence crabgrass control every year, so it has to be part of our standard application service," says Tim Doppel, president, Atwood LawnCare, Sterling Heights, Mich. "We use the products primarily for those crabgrass concerns, though there are some summer annuals that also may get a certain level of control."

To that end, in addition to controlling crabgrass before germination, many preemergence herbicide formulations offer the benefit of some early postemergence crabgrass control, as well as control of some other weeds. "Preemergents are primarily used to control crabgrass, but some also control other weeds, such as oxalis, henbit and spurge," notes Kyle Miller, senior technical specialist, BASF, Raleigh, N.C. "Lawn care operators often prefer using preemergence products because they allow the operator to control all of these weeds before they appear, saving them the time and cost of return trips and treatments."

Of course, preemergence herbicide manufacturers and LCOs agree that the only way to ensure sufficient weed control and fewer callbacks is to properly apply the products in the first place.

CLOCK CHECK. In terms of timing preemergence applications, "depending on the area of the country, preemergence herbicides are generally applied any time between February and May, and sometimes LCOs will make several applications in a year," Miller says. "There is research showing that preemergence herbicide applications in the fall are effective, but probably 95 percent of LCOs apply preemergents only in the spring, soon before crabgrass germinates."

Doppel agrees that spring applications are preferable. "Our first lawn care application will include preemergence crabgrass control – that’s around mid-March to early April," he comments.

With a relatively short crabgrass season in the northeastern part of the country, Doppel says one preemergence application is enough for his area, though LCOs in other regions have different considerations. "We have four preemergence applications in our eight-application program," says Gary LaScalea, president, GroGreen, Plano, Texas. "The markets change a lot as to preemergent needs depending on the weather conditions and crabgrass pressure in the Northern vs. Southern climates or the transition zone."

Because of the longer season in the warm Southern climate, LaScalea’s clients’ lawns are more prone to crabgrass than Doppel’s Michigan clients. Not only does that translate to more preemergence applications in general, but those applications are made in the fall as well as in the spring. "Down here, our clients go from wanting beautifully green lawns in the spring to wanting beautifully brown lawns in the winter," LaScalea explains. "Without fall preemergence applications, all those weeds would come up in the winter and there would be green spots of weeds in all the lawns. For instance, the Bermudagrass would be brown during dormancy, but the henbit and chickweed would grow in green. Our customers don’t want anything like that."

LaScalea usually makes his preemergence applications in February, March, September and October to control weeds all year long. He also uses split applications to gain season-long control. "Split applications are very common in many areas of the country," points out Dean Mosdell, Western technical manager, Syngenta, Greensboro, N.C. "In the upper Midwest and in the Northeast, crabgrass season is very short and one application of a preemergence herbicide is most common. But in most of the country, split applications are used to give a longer preemergence barrier and longer residual weed control."

In split applications, LCOs usually spread the full labeled rate of a herbicide treatment over two visits to a property. Mosdell says that the rates for split applications can vary depending on the location, herbicide and formulation. Also, depending on crabgrass pressure and the number of accounts that must be treated, LCOs may choose to apply more product during the first application and less during the second, or split the applications evenly between treatments.

Regardless of the application type, Eicher offers a range of costs LCOs can expect to pay for preemergence herbicides. On the low end, preemergents can cost $10 to $12 per acre and only control weeds before germination with little if any postemergent properties. These also may cause some staining. Mid-range products can cost $15 to $18 per acre and may provide some broadleaf weed control in addition to crabgrass control. The highest priced products can cost between $18 and $25 per acre but usually offer the best control over a variety of weeds with less staining.

"Those prices are applicable for straight herbicides or for the value of liquid herbicides applied to granular products," Eicher says. "LCOs in the North can expect prices in this range, but because LCOs in the South will often put out about twice as much product in a year, their costs can increase between 50 and 100 percent, depending on the product quality."

APPLICATION TIPS. Because most LCOs have no choice but to use pricey preemergence products in their lawn care programs, these applications often are cited as the least profitable. "The first application is not very profitable for us because of the cost of the preemergence material, which we have to amortize over the course of a season," Doppel says. "However, if you don’t use the material, then you end up with a higher level of customer dissatisfaction later in the summer because they’re seeing more crabgrass. You end up paying for that in the long run with callbacks or lost customers."

With that caveat in mind, LCOs must keep equipment calibration at the top of their preemergence lawn care checklists.

"I was at a product field day where the sponsor had a piece of lawn spraying equipment and was inviting LCOs to check the accuracy of their applications," Miller says. "It was amazing how inaccurate the applications were. People have to routinely calibrate their spray equipment to make sure they have accurate distribution. They may be using top-of-the-line products, but if they aren’t applied properly, they can’t control weeds well."

LaScalea takes calibration seriously. "Calibrations should be checked every day," he says. "We go out as a management team and do spot checks to make sure it’s being done. With a lot of spray equipment, this is done by spraying water into a bucket for 30 seconds or a minute and measuring the amount of liquid in the bucket, compared to the amount that you should have according to the label."

LaScalea explains that calibrating spreaders and sprayers is quite easy, but that some people in the industry seem to be moving away from that important step. "An operator once said to me, ‘Don’t tell me how much I need per 1,000 square feet – just tell me how much I need to put in 100 gallons,’" he recalls. "But you can’t do it like that because one person may use 100 gallons on 1 acre and someone else may use 100 gallons on 5 acres. Improper calibration is one of the biggest application mistakes."

Doppel agrees, adding that "the materials are too expensive to not put them down at the right rates and make sure applications are even over the whole lawn."

According to Mosdell, improper calibration can lead to applying either too much or too little preemergent active ingredient to a lawn. Also important is using an application technique that sufficiently overlaps spray gun or spreader passes on the turf. He recommends that LCOs evaluate their weed control programs annually to check the efficacy of their products and techniques.

"Because weed control is an expensive portion of your lawn care program, you want to make sure you and your clients are getting your money’s worth," Mosdell explains. "Look at the consistency of the product’s performance. There may be one or two lawns that have weed breakthroughs, but you have to determine if the reason was related to product performance, application error, poor turf quality or weather issues. Also, don’t only look at those one or two properties. What was the overall result of herbicide treatments during the year? Were there more callbacks than usual? Why? What do the issues have in common that may be related to the product, weather conditions and/or application?"

LaScalea also reiterates the golden rule for any lawn care application – herbicide or otherwise: "People need to read labels so they know the appropriate recommendations for the products they’re using," he says. "A lot of times you’ll want to stay on the high end of those recommendations and not cut costs because the results won’t be there. If you cut back on preemergents by even 10 percent, that might be enough to make a difference for the worse. These applications are part of what makes us professionals in the eyes of our customers, so we all need to make sure we’re making the right applications at the right times to keep our customers happy."

The author is assistant editor of Lawn & Landscape magazine and can be reached at lspiers@lawnandlandscape.com.