Effects of Insecticide Drench Application against Immatures of Systena frontalis in Container-grown Hydrangea paniculata

Systena frontalis (F.) (Coleoptera: Chrysomelidae), commonly referred to as the redheaded flea beetle, is a serious pest in container nurseries, as adult feeding defoliates nursery crops and affects plant salability. Because the foliar application of insecticides provides inconsistent efficacy, additional and alternative control tactics are sought to target immatures of this pest in growing media. Thus, the objective was to determine the effects of non-neonicotinoid insecticides applied as a drench to growing media on immatures of S. frontalis. In 2021 and 2022, nine active ingredients were evaluated in four trials in a Georgia nursery and at a Virginia research and extension center. If available, the maximum label rates for flea beetles or other coleopteran pests were applied once to Hydrangea paniculata Siebold containers (11.4 L, 3 gal) as a drench application. The emergence of S. frontalis adults from treated growing media and foliar feeding damage was lower for the tetraniliprole (TetrinoTM) and spinetoram + sulfoxaflor (XXpire®) treatments than for nontreated plants. Cyclaniliprole (SarisaTM) and chlorantraniliprole (Acelepryn®) suppressed S. frontalis adult eclosion with less feeding damage than the nontreated plants. Tetraniliprole, spinetoram + sulfoxaflor, and cyclaniliprole are not labeled for drench application. Dinotefuran (Safari®) effectively reduced adult emergence and feeding damage. Species used in this study: Redheaded flea beetle, Systena frontalis (F.); panicled hydrangea, Hydrangea paniculata Siebold. Chemicals used in this study: Cyantraniliprole (Mainspring®GNL), chlorantraniliprole (Acelepryn®), tetraniliprole (TetrinoTM), cyclaniliprole (SarisaTM), Spinetoram + Sulfoxaflor (XXpire®), tolfenpyrad (Apta®), Chromobacterium (Grandevo®CG), flupyradifurone (AltusTM), dinotefuran (Zylam® Liquid, Safari® 20G), and polyterpenes pinene (NuFilm® P).