Impact of Planting Date on Melanaphis sacchari (Hemiptera: Aphididae) Population Dynamics and Grain Sorghum Yield

Abstract

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has become a major pest of grain sorghum, Sorghum bicolor (L.) Moench, in the United States in recent years. Feeding by large densities of sugarcane aphids causes severe damage, which can lead to a total loss of yield in extreme cases. Our objective was to determine the effect of grain sorghum planting date on sugarcane aphid population dynamics and their potential to reduce yields. We conducted field experiments from 2015 to 2017 in which an aphid-susceptible grain sorghum hybrid was planted at four different dates, which encompassed the typical range of planting dates used in Arkansas production systems. Plots were either protected from sugarcane aphid feeding using foliar insecticide sprays, or left untreated to allow natural populations of sugarcane aphids to colonize and reproduce freely. Planting date impacted both the magnitude and severity of sugarcane aphid infestations, with the highest population densities (and subsequent reductions in sorghum yield) generally occurring on plots that were planted in May or June. Sugarcane aphid feeding reduced yields in the untreated plots in two of the four planting date categories we tested. Earlier planting generally resulted in less sugarcane aphid damage and improved yields compared with later planting dates. While the effect of planting date on sugarcane aphid populations is likely to vary by region, sorghum producers should consider grain sorghum planting date as a potential cultural tactic to reduce the impact of sugarcane aphid.

Grain sorghum production: Influence of planting date, hybrid selection, and insecticide application

“…Seiter et al. (2019) highlighted that aspect, showing that yields declined with later planting. They theorized that this was due to higher aphid densities.…”

“…They theorized that this was due to higher aphid densities. Shifting the planting date did not change the timeframe of infestation but solely the growth stage of the crop when the infestation occurred (Haar, 2018; Seiter et al., 2019). This emphasizes the potential of using planting date to aid in the management of sugarcane aphid, as up to 100% yield loss has been documented when sugarcane aphids infest at late vegetative to early reproductive growth stages compared with only 21% by soft dough (Catchot et al., 2015).…”

“…Bowling et al (2016) suggested that earlier planting would allow the crop to mature into later growth stages prior to aphid infes-tations, which would decrease the potential yield limitations that sugarcane aphid would cause. Seiter et al (2019) highlighted that aspect, showing that yields declined with later planting. They theorized that this was due to higher aphid densities.…”

“…This interaction between other control mechanisms and planting date has not been extensively documented in literature. Seiter et al (2019) noted that planting date could have an impact on insecticide use to control sugarcane aphids. They found no significant differences between plants treated and nontreated with early planting; however, significant differences occurred between applications when planting was delayed.…”

“…Earlier planting in more northern regions can allow the crop to further mature prior to aphid infestation, thereby decreasing damage to the crop (Bowling et al., 2016). Others have shown that earlier planting dates not only had a positive significant impact on limiting SCA populations but also resulted in increased sorghum yields (Haar, 2018; Seiter et al., 2019). However, in certain sorghum producing areas, there are other challenges that may arise when planting early.…”