Combining early planting date and in-furrow insecticide application for management of Melanaphis sacchari in grain and feed sorghum

The invasive sugarcane aphid (Melanaphis sacchari) is a serious pest of sorghum production in the southern US. As foliar application timing is critical for this pest, we investigated using in-furrow (IF) insecticide applications combined with early planting dates. Field trials with four treatments (untreated, 4 oz Sivanto HL IF, 5 oz Sivanto HL IF, 5 oz Sivanto Prime foliar) and two planting dates (mid-April and late May) were conducted on grain and feed sorghum. Number of sugarcane aphids on upper and lower leaves in each plot and plant condition was rated weekly. Sugarcane aphids first appeared in the early planted plots in early June and exceeded the treatment threshold (50 per leaf) within two weeks. Late planted plots received aphid detections in late June and exceeded the treatment threshold within 1 week. Aphid infestations were always greater in the untreated compared to the treated plots in both grain and feed sorghum. A single foliar application to selected plots immediately brought the infestation below threshold while untreated plots continued experiencing extremely high infestations. Aphid counts never exceeded the treatment threshold in either of the in-furrow treatments in both grain and forage sorghum. Although sorghum yield in the late planted plots was considerably less than the early planted plots, the two in-furrow treatments and the foliar treated plots increased grain yield by nearly 60% compared to the untreated control. These findings suggest that early planting combined with in-furrow or foliar insecticide application could provide acceptable sugarcane aphid suppression.