Fight Fire With Fire

It started small, but high winds pushed it into dry, overgrown vegetation, treetops and wood-shingled roofs, where it jumped from home to home. Out of control within minutes, a rainstorm of burning embers erupted.

According to the Environmental Health Center, Washington, D.C., it was a wildfire that destroyed 2,886 homes and caused $1.5 billion worth of damage in Oakland and Berkeley, Calif., on Oct. 20, 1991.

Wildfires like this one spread so rapidly that they stun residents, even in areas where they are common.

The same can be said for fire ants, a known burden to southern U.S. residents, yet still alarming when they strike an allergic victim en force.

Even though they aren’t considered turf-damaging insects like grubs, fire ants are an unwanted bother and are spreading further north every year, which is why lawn care operators (LCOs) nationwide have to educate themselves on the life cycle, habits and control methods of these assiduous insects.

But, be warned. Initiating a fire ant control program is a long-term commitment for LCOs and their clients, pointed out Rick Brandenburg, turfgrass entomologist, North Carolina State University, Raleigh, N.C. “To back off from a long-term regular treatment schedule once it has been initiated is a sure-fire approach for the fire ants to return with a vengeance,” he said. “Don’t expect any miracle cures and don’t expect fire ants to just go away – they are here to stay. Only through diligence, commitment to a sound program and an understanding of the ants and the products we use to control them can one be successful in the fight.”

FIRE ANT FACTS. To scout for these reddish-brown pests, LCOs first look for mounds, which are the most obvious part of a colony. Soil texture and moisture and colony size and age determine a mound’s height and depth. “For example, a mound that is 2 feet in diameter and 18 inches high contains about 100,000 workers, several hundred winged adults and one queen,” said Frank Womack, agrostologist, Greensmiths.com, Frisco, Texas. “Mounds constructed in clay soils are symmetrical and dome-shaped; mounds built in sandy soils are irregularly shaped.”

Ray Schad, branch manager, McCall Services, Orlando, Fla., also looks for soft spots or holes insandy soil to uncover fire ants on a property.

And if LCOs haven’t noticed fire ants on a site, clients usually let them know, especially after rainstorms, observed Mark Gill, owner, Spring-Green Lawn Care, Columbia, S.C. “Worker ants are more active then, searching for food to bring to the colony,” he said.

TREATMENT TACTICS. “There are no natural predators for fire ants in our region except for us,” Gill said, which is why LCOs must develop adequate control approaches.

There are two basic management methods: curative mound treatments and preventive and curative broadcast applications.

Mound Treatments. Mound treatments come in a variety of formulations, including drench, dust and bait. These treatments are meant to eliminate mounds one at a time and their use challenge typically lies in colony depth.
“On the surface, you see a superficial representation of the true colony size,” Schad said. “The majority of the colony is subterranean. They maintain tunnels down to the water table to bring water to the colony, even in drought. You could have tunnels 8 to 10 feet deep, so you need to continually spot treat mounds and keep an eye out for new mounds afterward.”

Dusts work best in mid- to late afternoon and when irrigation can be delayed for 24 hours. And with drenches, LCOs can obtain the best control in spring and fall when the temperatures are between 70 and 85 F because during the hot, summer months ants remain deep within their mounds and are hard to reach with liquid insecticides, Womack said.

“To be effective, a drench must trickle down through the mound and contact most of the fire ants,” Womack said. “Ants contacted by the drench die in less than 24 hours.”

Bait, which consists of a food item desirable to fire ants combined with a slow-acting toxicant or a growth regulator, also can be an effective mound treatment or broadcast application because worker ants collect food to feed the colony, said Linda Hooper-Bui, associate professor, department of entomology,

Louisiana State University AgCenter, Baton Rouge, La. “Worker ants collect the bait and then pass it around to other members of the colony who eventually succumb to the toxicant’s effects or be rendered sterile from the growth regulator,” she said.

A fall bait application (August through October) is important because it helps suppress ants by the following spring, Drees said. “Generally, if you make a spring application, suppression should last until that fall, when the next application should be made,” he said.

Application Methods. Therefore, using proper application techniques is vital. Most mound treatment products direct the user not to disturb the mound prior to application, thereby concentrating ants close to the surface where the solution will more likely contact them when they scatter to defend the mound, pointed out Bastiaan Drees, fire ant project coordinator, department of entomology, Texas A&M University, College Station, Texas. “Also, queen ants reportedly move deeper into the mound upon disturbance, reducing the possibility of contact with the solution,” he said. “Some products instruct the user to poke a hole into the top of the mound. This action provides a point of entry to allow the solution poured into the hole to flood the tunnels in the mound, but also causes a mound disturbance.”

Additionally, LCOs should not only cover the actual mound, but also the soil 3 to 4 feet around the mound. “This is because mounds have subsurface tunnels radiating away from the mound proper, which can harbor ants and queens,” Drees explained. “This is often the case with colonies nesting next to curbs and other objects where the nest is actually under the object but the mound is built next to the object. In these situations, mound drench treatments may be ineffective because not all of the ants in the colony come in contact with the insecticide.”

Although the bait insecticide kills the queen, worker ants may be active inside the mound for several weeks before the colony finally disappears, Womack said. “Baits are fairly slow acting but easier to apply than mound drenches,” he stated. “Therefore, they are best used in situations where many mounds must be treated, when water for mixing mound drenches is difficult or impossible to obtain or when the risk of human contact is low and there is no urgent need to eliminate the infestation.”

Bait results can be short-lived, though, because their active ingredients rapidly degrade in high temperatures, high humidity and intense sunlight, Womack added. Hence, the key to using baits is patience, Drees advised. “Baits will provide 80 to 90 percent control – rarely 100 percent,” he said. One of the greatest difficulties with broadcast treatments of bait formulations is the low rate, added Tim Davis in the Southern Lawn Handbook. “Most call for 1 to 1½ pounds per acre,” he said. “This is a small amount for a large area and overapplication is common. For most situations, spreaders can be used. The opening, however, must be a minimum of 1/8 inch or calibrated correctly for spreading fire ant baits. Baits can be used as individual mound treatments but are more effective as broadcast treatments.”

Broadcast Treatments. Broadcast application methods also come in liquid and granular formulations that can be used curatively or preventively. 

Hooper-Bui’s research shows that broadcasting either granular pesticides or baits throughout areas works better than treating individual mounds. Many LCOs believe granular pesticides work even better than baits as broadcast applications since the application rate isn’t as low and more active ingredient used per 1,000 square feet of turf typically means more dead fire ants, said John Buechner, director of technical services, Lawn Doctor, Marlboro, N.J.

“With newer products, we haven’t seen as low of a rate – we’ve seen more of a 2- to 3-pound rate per 1,000 square feet vs. a 1- to 1½-pound rate per 1,000 square feet,” he remarked.

Length of control is another reason many LCOs are incorporating broadcast applications into their programs. “We started using a preventive granular application earlier this year and are getting good results – it’s kept out fire ants for three to four months and we’re hoping it will last one year,” Schad said.
The only disadvantages are that results appear slowly – it takes about four to six weeks to see them – and the initial cost is greater for this type of granular broadcast application product, Schad said.

Of course, a treatment is only as effective as the applicator’s knowledge of proper procedures. “Nobody’s perfect – you can’t remove human error from the equation,” Schad said, adding that he will retreat a client’s lawn at no extra charge if the problem wasn’t fixed due to possible applicator ignorance.

To ensure a control product sticks around, LCOs should not water heavily after mound treatments or broadcast applications, Buechner advised. “You want the product to stay on the surface as long as possible,” he said. “Also, avoid any mechanical disruptions with mowers or equipment.”

Additionally, LCOs should discourage heavy traffic on a site after treatment. “We tell clients they can assume regular use of the property after 48 hours,” Schad said.

CLASSIC COMBINATIONS. “Regardless of the method used, the objective of a broadcast application or mount treatment is to kill the queen because she is the only ant in the colony who lays eggs,” Womack stressed. But this is hard to do. Many LCOs find they must combine mound treatments and broadcast applications to reach the queen.

“The best method of control we’ve found so far is an overall even application of a preventive granular broadcast application product mixed with bait applied to mounds for a quick knockdown,” Schad remarked.

Gill also uses a combination of products as a means of overall fire ant control. He prefers to use a broadcast bait product that contains a growth regulator in addition to a liquid broadcast insect control product. He includes a mound treatment application in his regular weed and fertilization service. But if fire ants are out of control on a specific property, he will include the broadcast bait product twice a year for $55 each time – considering that the client’s typical treatment for weed-and-feed was about $40 per application based on their lawn size.

According to a Lawn & Landscape and Chipco Professional Products survey, 57 percent of LCOs charge for their fire ant program per application. The average amount  LCOs charge for a fire ant treatment is $63 to single-family homes and $142 to commercial/industry customers.

Like Gill, Jeff Michel, training and technical director, GreenUp Division, Massey Services, Maitland, Fla., also uses a liquid treatment for control in addition to spot applications with granular insecticides. “These treatments provide control of foraging fire ants and have an added benefit of controlling most lawn-damaging insects, like chinch bugs,” Michel said, adding that his program is mostly curative – currently, he won’t treat an area preventively for fire ants unless clients specifically request it because he’s not confident that he can prevent them. “Spot treatment with insecticides can control a mound, but without a larger broadcast application, it is difficult to control all of the colonies in the landscape. We have great success killing fire ants. The difficult part is killing all of them in the landscape so they do not return.”

Whatever control combination LCOs choose to use in their battle against fire ants, gaining education on available products to build confidence and, then, passing this knowledge and optimism onto clients is the only way to victory. “Sure, you can build a house of sticks, but you want it to stand, don’t you?” Schad explained. “You don’t want it to blow down and then you have to keep rebuilding it. It’s the same with fire ants. You have to do something up front to get rid of them – this is just what it’s going to take.”

The author is Managing Editor of Lawn & Landscape magazine and can be reached at nwisniewski@lawnandlandscape.com.