Control of fall armyworm with labeled and experimental insecticides in sweet corn, spring 2023

FAW can be a destructive pest of sweet corn and can cause significant yield reduction by feeding on whorls, tassels, silks, and ears. Rotations of insecticide mode of actions are necessary to reduce the chances of insecticide resistance and new formulations are important for more sustainable FAW control programs. This trial was conducted at the Southwest Florida Research and Education Center in Immokalee Florida on 2 beds, 32 inches wide and 400 ft long on 12 ft centers and seeds planted in 2 rows per bed on 13 Dec at 10-inch spacing. Three treatments and an untreated check were assigned in an RCB design with 4 replicates (Table 1). Each plot contained 30 plant spaces (60 total in the two rows) and 6 plants per row (12 total) were used as buffer between plots. Applications were initiated on 13 Jan (Table 1) prior to the plants starting to push their tassels and were conducted with a high clearance sprayer moving at 2.3 mph equipped with 4 ceramic Albuz ® ‘yellow’ hollow cone tips each delivering 10 gpa at 180 psi for a total of 40 gpa. Applications were conducted as per Table 1. Nozzle location was adjusted to concentrate sprays on tassels, silks or ears when appropriate to ensure larval exposure to spray material. Feeding damage rating was conducted on the whorls and tassels from 0 to 5; 0 = none, 1 = <5% damaged, 2 = 6 to 33%, 3 = 34–67%, and 4 = >68%. The visible larvae were counted on the whorls on 18 and 25 Jan. The number of feeding holes were counted on the developing ears on 8 and 15 Feb and ears were collected 3 Mar. Damage to the cob was determined and grouped into 3 categories: no damage, tip damage, and ear damage. For the analysis, damage categories were combined, and ears were considered as either damaged or marketable. Data were analyzed using ANOVA, and differences among treatment means on each sampling date were determined using LSD test (P = 0.05).

FAW pressure was moderate in this trial, all damage observed is attributed to the FAW. Significantly fewer FAW larvae were found in all treatments on 25 Jan with relatively more suppression with both rates of Plemax than the Avaunt eVo/Rimon rotation (Table 2). Damage observed was only significantly lower in the Plemax treatments when compared to the untreated check but the difference between the Plemax and Avaunt eVo/Rimon treatments was not significant.

All treatment programs reduced the number of feeding holes observed in the exterior husks on 8 and 15 Feb (Table 2), and all programs increased marketable yield and reduced ear damage (Table 3). No phytotoxicity was observed.¹

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