FIRE ANTS can be controlled in pastures, but the choices for achieving that goal are limited, according to LSU AgCenter entomologist Jack Baldwin, adding that Amdro Pro, Extinguish, Justice and Sevin are the only insecticides labeled for livestock pastures and hay meadows.
Fire ants can be controlled by treating individual mounds or by broadcasting a bait over the entire area. “Treating mounds individually usually is not the most efficient approach in most pastures, because of the large area to be covered and the probability of missing some mounds.”
Fire ant baits should be broadcast uniformly over the entire pasture, Baldwin advises, saying it is better to leave narrow streaks in the bait application than to miss whole areas of the pasture.
“Mixing fire ant baits with granular fertilizer may impair the attractiveness of the bait, thus reducing fire ant control,” he says, explaining, “When a granular fertilizer is premixed with the bait, it will eventually degrade the vegetable oil component of the bait and make it rancid. Therefore, if a bait is blended with fertilizer, it should be applied immediately.”
Baldwin also provides this information on the materials available for pastures and hay meadows:
Extinguish is an insect growth regulator that inhibits reproduction by the queen. It does not kill worker ants. Mounds die out from attrition, because no new ants are produced to replace those that die due to natural causes. This bait can be very effective, but it acts slowly and may require six to eight weeks before you see the maximum effect in terms of dead mounds. The broadcast treatment rate is 1.0 to 1.5 pounds of product per acre. It also can be applied as an individual mound treatment.
Amdro contains a toxicant that kills ants, including the queen, when consumed within the mound. It is not fast-acting, but a reduction in live mounds should be seen in about three weeks. The broadcast treatment rate is 1.0 to 1.5 pounds of product per acre. It also can be applied as an individual mound treatment.
Justice is a relatively new fire ant bait for livestock pastures. It can only be used for mound treatments, however, since it is not labeled for broadcast application. Control with this toxicant bait is rapid, and mounds should die out in about a week. Producers can expect about two months of long-term control following treatment.
Sevin is an old product that is available in several formulations. It is applied as a mound drench. Producers should mix according to label instructions and apply 2 gallons of solution per mound or at least 1 quart per 6 inches of mound diameter. Mounds can be retreated with Sevin in seven days if fire ant activity persists.