Effects of insecticides applied in-furrow with superabsorbent polymer on peanut cultivars infected with Tomato spotted wilt virus

Abstract

Spotted wilt of peanut (SWP) (Arachis hypogaea L.) caused by Tomato spotted wilt virus (TSWV; family Tospoviridae, genus Orthotospovirus) is a common disease that causes severe economic losses in peanut producing regions of the world. The causal agent is transmitted by thrips (Thysanoptera: Thripidae). Field experiments were conducted in 2017 and 2018 to determine if management of spotted wilt and subsequent productivity of peanut, including economic value, could benefit from applying a superabsorbent polymer (SAP) with standard in-furrow insecticides at planting. To determine this, two individual experiments were performed. In the first study, phorate and imidacloprid were individually applied with (2.24 kg/ha) or without SAP across cultivars susceptible (FloRun 157 or TUFRunner 511), moderately susceptible (Georgia 06G), and resistant (Sullivan or TifNV-High O/L) to TSWV. Nontreated controls were included in all experiments. The second study sought to determine the efficacy of different rates of SAP (0, 2.24, 5.6, and 8.97 kg/ha). The initial study was conducted in three locations across South Carolina and Georgia, while the second was conducted at Blackville, SC. In the first study, incidence of SWP was reduced (P = 0.0547) in multiple location-year analysis with a reduction of 9.4% observed in susceptible cultivars treated with phorate compared to untreated checks and those with imidacloprid. SAP did not affect final SWP incidence or economic value (P > 0.05) and was not consistently significant for yield. From the SAP rate study, a linear relationship of decreasing SWP incidence was observed with increasing SAP application rates for both imidacloprid and phorate in 2017 and 2018. On a means comparison basis, SWP was lower than the no-SAP check at SAP rates of 5.56 and 8.97 kg/ha, but this did not necessarily translate into increased yield. Additional experiments are needed to elucidate the relationship superabsorbent polymer may have to susceptible cultivars and phorate.