What Fire Ant Problem?

Imported Fire Ants November 04, 2011|Print

Oak Valley Farms in Munford, Alabama is a purebred Angus cattle operation that had a serious fire ant problem. A survey of pastures on the farm found an average of 236 live mounds per acre. It is easy to assume that such a fire ant population could disrupt cattle grazing and cause problems during the calving season and that immediate control of fire ants was necessary.

With a state beef check-off grant from the Alabama Cattlemen’s Association, I set up a demonstration to evaluate the effectiveness and economics of treating cattle pastures with a fire ant bait product.

Using a Herd GT-77 seeder calibrated to spread 1.5 pounds of bait per acre, a 50/50 blend of Amdro Pro® and Extinguish® fire ant bait was applied to approximately 12 acres using a skip-swath method. For comparison, an adjacent twelve acres were left untreated.

The seeder is equipped with a restrictor-plate that allows easy calibration of any bait product and will spread bait in a 20-foot swath. It is well known that fire ants can forage over 100 feet from the mound for food. Therefore, it makes sense that not every square foot of pasture needs to be treated. The skip-swath method simply leaves every other swath untreated, allowing producers to cover more acres with one bag of bait, thus reducing the cost of application.

The 50/50 bait blend was applied on June 17, 2005. Four sampling plots were established within each of the treated and untreated areas. At the time of application the treated and untreated areas had an average of 239 and 234 mounds per acre, respectively.

  • In November 2005, evaluation of the project revealed an overall 90% reduction of fire ant mounds in the treatment area, while the untreated area had a 5% increase.
  • On April 28, 2006, 10 months after treatment, the fire ant population had fallen slightly in the treated area to 20 mounds per acre while the untreated area remained relatively unchanged at 235 mounds per acre.

The cost of this application was $5.94 per acre. This is inexpensive, especially for a farm as heavily infested with fire ants as Oak Valley Farms was. My best recommendation is to treat pastures once a year, every year, with a bait product using the skip-swath method. However, some farms can get by with one treatment every other year.

One question you need to ask yourself is “How many fire ant mounds can I live with?” We cannot eradicate fire ants from our pastures because new queens will reinfest the area during the warmer months if conditions are favorable. Single-queen colonies of fire ants are very territorial and will kill all new queens entering their territory as long as their queen is alive. So, it is to our advantage to tolerate a few mounds per acre to take advantage of that natural control. As long as the fire ant population is below your tolerance level, there is no need for treating. But one thing is for sure, you will have to treat again at some point to maintain the population at an acceptable level.

The big question is “What bait should I use?” There are only a few baits labeled for use in cattle pastures and hayfields and they basically work in one of two ways:

  • Fast-acting baits are insecticide-based baits that kill the queen, immatures, and adult fire ant workers and typically control the colony in two to four weeks.
  • Insect Growth Regulator-based baits (IGR) prevent new fire ants from developing and can take as long as four to twelve weeks for complete control of a colony. IGR-based baits allow you to take advantage of the territorial nature of fire ants and minimize reinfestation because the queen does not die; the colony slowly disappears as the workers die off naturally and no new workers develop. Ultimately, the queen dies when no workers are left to take care of her.

Effective and economical control of fire ants is easy to achieve and can have a beneficial effect on your cattle or farm operation. If you live in Alabama and are interested in treating your property, you can do so easily by using one of 40 Herd GT-77 spreaders located at Extension offices in Alabama. Contact your local county Extension office or your Regional Extension Animal Science Agent to schedule the use of one of the spreaders free of charge.

To see the complete text with accompanying figures, see the original article, What Fire Ant Problem?

Adapted from an article for August 2006 Cooperative Farming News, written by Henry Dorough Regional Extension Agent Animal Science & Forages East Alabama, Piedmont Region

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