LAUSR

Simple Summary Infestation of forage sorghum by Melanaphis sorghi remains a major threat to silage production in the southeastern USA. Studies aiming to refine IPM strategies are crucial to improve management of this invasive pest. Here, we investigated the impact of planting date and insecticide application methods, including in-furrow vs. foliar applications, on M. sorghi infestation and grain sorghum yield in Tifton, GA, and Florence, SC, USA. In-furrow applications of flupyradifurone significantly suppressed aphid infestations in both the early and late planted sorghum at both study locations in both years, while aphid populations were also successfully suppressed following the foliar application of the insecticide after threshold numbers of aphids per leaf were reached. Early planting and in-furrow insecticide application improved yield the most at Florence in the 2020 study. However, in years of low aphid abundance, no difference in yield was observed between treatments, including untreated. This research demonstrates that early planting and in-furrow and foliar insecticide applications provided sufficient protection to prevent significant yield loss. Thus, this suggests that early planting of forage sorghum combined with in-furrow and foliar insecticide applications can suppress aphid infestations and improve silage production in southern USA. Abstract Studies on the management of the invasive Melanaphis sorghi are essential to refining integrated pest management strategies against M. sorghi in forage sorghum in the USA. The objective of this study was to determine the impact of planting date (early planting and late planting) and in-furrow and foliar insecticide application of flupyradifurone, on M. sorghi infestation and forage sorghum yield in Tifton, Georgia and Florence, South Carolina, USA, in 2020 and 2021. Early planted sorghum supported slightly higher aphid density and severity of infestation as evident in the greater cumulative insect days values in the early planted sorghum at both Florence and Tifton in 2020 and 2021. A single foliar application reduced aphid infestations below the threshold level of 50 aphids per leaf. In contrast, in-furrow insecticidal application in selected plots at both locations significantly suppressed M. sorghi density to near-zero levels. Yield results in Florence in 2020 showed that sorghum yield was over 50% greater in early planted plots compared to late planted plots. Both insecticide treatments (foliar and in-furrow) resulted in significantly higher yield than untreated plots. These data indicate that early planting coupled with in-furrow and foliar insecticide applications can suppress M. sorghi infestations and improve silage production in forage sorghum in the USA.