Insecticidal Control of Fall Armyworm on Sweet Corn, 2013 *

FAW is the key pest of sweet corn in southern Florida, with larvae feeding successively in whorls, tassels, silks, and ears. Selective chemistries are being sought to provide better and more sustainable FAW control. The trial was conducted at the Southwest Florida Research and Education Center in Immokalee, FL, on two sets of three raised beds 32 inches wide and 420 ft long on 6-ft centers on 17 Aug. Fertilizer (10-2-10) was incorporated at 100 lbs N, and beds were fumigated with MBC 50/50, provided with two drip tape irrigation lines with 8-inch emitter spacing, and covered with white-faced polyethylene mulch. Corn was direct seeded on 6 Sep at 10-inch spacing with two seeds per hole and a 7-2-7 liquid fertilizer was injected through the drip using a Dosatron ^® over the growing season. Nine treatments were assigned in an RCB design across four replicates with the center row of each three-bed set left untreated as a pest refuge and buffer area between treated rows. Applications were made with a high-clearance sprayer traveling at 2.3 mph equipped with four ceramic Albuz ^® “yellow” hollow cone tips each delivering 10 gpa at 180 psi for a total of 40 gpa. Larval counts and damage assessments were made on 15 plants per plot noting the number of larvae in the top of the whorl (7 Oct), and tassel (15 Oct). Damage assessments on whorls (7 Oct) and tassels (15 Oct) were rated 0–5: 0 = no damage, 1 = <5%, 2 = 6–25%, 3 = 26–50%, 4 = 51–75%, 5 > 76% and ears (25 Oct and 4 Nov): 0 = no damage, 1 = 1 hole in husk, 2 = 2 or 3 holes in husk, 3 = 4 or 5 holes, and 4 = 6 or more holes in husk. The dominant ear on 15 plants was harvested on 11 Nov and graded into three categories—no damage, minor tip damage, and significant ear damage. Marketable ears were weighed as a group. After 15 Oct, one plot assigned to Besiege, Lannate, and Warrior was eliminated from the analysis due to a misapplication. Data were subjected to ANOVA and means separated using LSD ( P  = 0.05).

All products reduced damage to whorl, tassel, and ears compared with the untreated check ( Table 2 ). Plants receiving treatments including either ISK 3106 or Besiege showed significantly less tassel and ear damage than the other treatments including a grower standard rotation of Lannate and Warrior. Larvae followed similar trends except that MBI206 or MBI206-SEI @ 4 qt on 7 Oct or the latter at 2 qt on 25 Oct were not different from the check. Greatest number and weight of ears were taken from plants receiving treatments that included either ISK-3106 or Besiege, followed by the Lannate–Warrior rotation, with little or no effect seen with the remaining treatments. No treatment reduced tip damage, although ear damage was again most reduced by treatments including either ISK-3106 or Besiege followed by Lannate–Warrior and also MBI206 @ 4 qt or MBI206-SEI @ 8 lb/acre. No phytotoxicity was observed in this trial.

Author notes