D. A. Webb

Southern fire ant (FA); Solenopsis xyloni McCook
Pavement ant (PA); Tetramorium caespitum Linnaeus

Calvin Fouche, Dawn Brunmeier,
Win Rogers, Don Colbert

University of California
420 South Wilson Way
Stockton, CA 95205
Phone: (209) 468-2085
Fax: (209) 462-5181
Email: bfouche@ucdavis.edu

CONTROL OF SOUTHERN FIRE ANTS AND PAVEMENT ANTS IN ALMOND ORCHARDS USING BAITS, 1998: Six treatments, four in bait form, were evaluated in an orchard near Escalon, CA, to determine their effectiveness in controlling nut damage by FA and PA. The experimental design was a RCB with 5 replications. Plot size was 5 rows of 6 trees each, with rows and trees spaced at 24 ft. Trees were in the ground two years and not yet bearing nuts. The orchard was irrigated once every two weeks with solid set sprinklers. All treatments were applied on 20 May. Knack and Logic were reapplied over the same plots on 21 Jul. Clinch, Amdro and Lorsban were reapplied on 31 Aug. Baits were applied by placing measured amounts as piles in approximately 84 locations toward the center of each 30-tree plot. Lorsban was applied in 50 gallons of water per acre using an orchard type handgun for the first application and a 10 ft boom for the second. Two passes down each row were made using six 11004 vs nozzles on 20 inch centers at 35 psi. For the 2 Jun through 25 Aug samples, eight 14-dram vials were placed in the center of each plot for 24 hours. In each vial, a section of hot dog, approximately 1 cm long, was used as bait. The vials were capped as they were collected, taken to the lab and frozen. Ants in the vials were identified, counted, and the percent of surface damage to hot dog was recorded. Almonds were set out on 14 Sep for a harvest evaluation, however almost no feeding occurred on the nuts. The ants were observed feeding extensively on spurge seed at this time and could not be induced to switch to our test vials with almonds.

PA's were controlled by Clinch, Amdro and Lorsban within two wks of the first application, and provided suppression for 14 wks following. Knack and Logic took 8 wks to control PA, but the control lasted until the time of the second application on 31 Jul. FA numbers were low in the beginning of the trial until the 11 Aug evaluations. Knack, Logic and Lorsban provided reductions in numbers compared to the untreated check. While the Clinch and Amdro treatments were able to control PA, the counts of FA in the Aug evaluations increased to levels above the untreated checks. In early Jul all materials were able to reduce damage levels. In the 28 Jul and Aug evaluations, Knack and Lorsban were the most effective in reducing damage.