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

Fall armyworm (FAW) can be a destructive pest of sweet corn and can cause significant yield reduction by feeding on whorls, tassels, silks, and ears. This trial was conducted at the Southwest Florida Research and Education Center in Immokalee Florida on 3 beds, 32 inches wide and 400 ft long on 12 ft centers. Seeds were planted on 28 Sep at a 10-inch spacing. Five treatments and an untreated check were assigned in an RCB design with 4 replicates (Table 1). Each plot contained 35 plant spaces and 10 plants were used as buffers between plots. Applications were initiated on 27 Oct (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. The 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% to 67%, and 4 > 68%. The visible larvae were counted on the whorls on 31 Oct and 7 Nov and on the tassels on 15 Nov. Ears were collected on 7 Dec. 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 only as damaged or marketable. Data were analyzed using ANOVA, and differences among treatment means on each sampling date were determined using the LSD test (P = 0.05).

FAW pressure was moderate in this trial, all damage observed is attributed to the FAW. Significantly less damage was found in all treatments on all sample dates when compared to the untreated check (Table 2), and significantly fewer larvae were observed in the plant whorls but not the tassels (Table 2).

All programs increased marketable yield and contained fewer FAW larvae at harvest when compared to the untreated (Table 3).

No phytotoxicity was observed.¹

Footnotes