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Managing Fire Ants in the Vegetable Garden

Fire ant mound located in a mulched area of a vegetable garden.

Fire ant mound located in a mulched area of a vegetable garden.
Joey Williamson ©2010 HGIC, Clemson Extension

Fire ants are a common nuisance in home vegetable gardens. In addition to being a stinging pest, they can cause damage to vegetable crops, such as okra and Irish potatoes. In dry conditions, they may also damage tender seedlings and transplants by feeding on the stems. There are two main strategies for managing fire ants in vegetable gardens: applying baits and treating individual mounds.

Fire Ant Baits

Applying an ant bait is the most effective means of managing fire ants in a vegetable garden. This involves broadcasting a granular material that includes an insecticide and an attractant, usually soybean oil. The ants collect the granules and carry them back to the colony, inadvertently killing many of its members. A single bait application can reduce fire ant populations by around 80%. Be sure only to use baits that are specifically labeled for use in vegetables.

Spring is usually the best time to apply baits, though if heavy fire ant activity is expected, an application can be made in the fall, followed by another in the spring. If ant activity persists throughout the growing season, a summer application can be made as well.

Applications should occur when ants are active and foraging. Fire ants are typically active on sunny days when the temperature is above 65 °F. Check to see if ants are foraging by scattering a few potato chips (the greasier, the better) around the garden. If ants have found the chips within 20 to 30 minutes, they are foraging and will find the bait and gather it relatively quickly.

Check the weather forecast and broadcast bait when rain is not expected for a day or two following the application. Rain will wash away or dissolve bait granules. If applying after rain or early in the morning, wait until the ground is dry.

A handheld seed spreader may be used to apply baits and can provide relatively even distribution. Typical fertilizer spreaders will put out way too much bait and should not be used. Additionally, fire ant baits should not be mixed and applied with granular fertilizers as the fertilizer will absorb some oil from the bait, making it less attractive to the ants.

While fire ant baits with other active ingredients exist, Spinosad-based products are the most economical for home gardens. Spinosad products are very effective, but it is important to remember baits are relatively slow acting. It will take two to three weeks to see results.

Most fire ants that invade vegetable gardens come from mounds located in adjacent lawns; therefore, managing ants in the lawn can be very helpful at reducing populations within the garden. Again, be sure any baits that do not specifically mention vegetables on the label are not applied to the vegetable garden. For detailed instructions and tips on managing fire ants in lawns, see HGIC 2502, Hints and Tips for An Effective Fire Ant Management Program in Home Landscapes Using Broadcast Baits.

Individual Mound Treatments

Individual mounds may be treated if they persist following bait treatments. The previously mentioned bait materials include instructions on their labels for treating individual mounds. In addition, there are a few liquid and granular mound treatments available that are labeled for use in a vegetable garden.

When treating mounds with granular baits, gently sprinkle the bait in a 4-foot circle over and around the mound. Do not wet the bait or apply if rain is expected on the same day.

For other granular mound treatments, apply the granules evenly to the mound’s surface and thoroughly water the treated area afterward.

For liquid mound drenches, mix up a 1-to 2-gallon solution using a watering can or bucket, according to the instructions on the product label. Pour approximately 10% of the solution around the perimeter of the mound about 12 inches away. Pour the rest of the solution directly on the mound. When applied properly, mound drenches work relatively quickly (just a few hours).

Never use products containing acephate for mound treatments in the vegetable garden (Hi-Yield Acephate Fire Ant Killer, Ortho Orthene Fire Ant Killer, or Surrender Fire Ant Killer). Acephate is labeled to treat fire ant mounds in home lawns, but it is not labeled for vegetables.

Table 1. Products Labeled for Fire Ant Management in Vegetable Gardens.

Active Ingredient Trade Name Restricted Entry Interval (REI) Pre-harvest Interval (PHI) (Days)
Granular Baits
Spinosad Come and Get It! (Ferti-lome) 4 hrs 0
Pay Back (Southern Ag) 4 hrs 0
Liquid Mound Drenches
Spinosad Conserve SC (Corteva) 4 hrs 1-60, See label**
Captain Jack’s Dead Bug Brew (Bonide) 4 hrs 1-60, See label
Colorado Potato Beetle Beater (Bonide) 4 hrs 1-60, See label
Borer, Bagworm, Tent Caterpillar & Leaf Miner Spray (Ferti-lome) 4 hrs 1-60, See label
Monterey Garden Insect Spray* 4 hrs 1-60, See label
Natural Guard Spinosad* 4 hrs 1-60, See label
Conserve Naturalyte Insect Control* (Southern Ag) 4 hrs 1-28, See label
Permethrin Eight Insect Control Vegetable, Fruit, and Flower (Bonide) Until dry 0-22, See label
Granular Mound Treatments
 
Bifenthrin Hi-Yield Ant Killer Granules 12 hrs 1-7, See label
Eight Insect Control Flower & Vegetable Insect Granules (Bonide) 12 hrs 1-7, See label

*OMRI Listed

**Check the label for the PHI for each specific crop

Always read the product label for application rates and information about where and how to use insecticides safely. Make sure any insecticide used in the vegetable garden is specifically labeled for the vegetables being grown and the targeted pest.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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