Performance of organic and conventional insecticides for management of Rhopalosiphum rufiabdominale in hemp

The rice root aphid (RRA), Rhopalosiphum rufiabdominale (Hemiptera: Aphididae), is a below-ground feeding insect that is difficult to control and has become a major pest in hemp production, affecting plants grown under both field and greenhouse conditions. The objective of this study was to evaluate the efficacy and phytotoxicity of three unregistered conventional insecticides: Senstar® (spirotetramat (11.47%) + pyriproxyfen (4.01%)), Harvanta® 50SL (cyclaniliprole, 4.55%), and Beleaf® 50 SG (flonicamid (50%)) against RRA and compare them with three biologically based products: Pyganic® (pyrethrin 5%), Azaguard® (azadirachtin, 3%), and BoteGHA® (Beauveria bassiana strain GHA, 11.3%) under greenhouse conditions. Experiments were conducted at the University of Kentucky Research and Education Center at Princeton. In the first trial, the initial spray was applied on July 16; in the second trial, the first spray was applied on October 29, 2024. Each insecticide was applied four times, with a 7-day interval between applications. In both trials, the conventional insecticides effectively controlled RRA after the second application but showed varying degrees of phytotoxicity. Among them, Senstar ®was the least phytotoxic. In contrast, the results with the biological products were inconsistent. Pyganic® showed high efficacy and relatively low phytotoxicity in the first trial (July–August), but its performance declined in the second trial (October–November). Azaguard® and BoteGHA® performed poorly in the first trial; however, in the second trial, they achieved 76% and 92% control efficacy, respectively, by the end of the experiment.