Influence of Planting Date, Fungicide Seed Treatment, and Phorate on Peanut in North Carolina

Abstract

Establishing an adequate stand of peanut (Arachis hypogaea L.) and minimizing the negative impact of tobacco thrips [Frankliniella fusca (Hinds)] is important for maximizing yield in both organic and conventional production systems. The incidence, severity, and impact of soil borne pathogens and thrips populations on peanut may be influenced by planting date, fungicide seed treatment, and/or systemic insecticide application. However, the interaction of these management techniques has not been investigated in North Carolina with Virginia market type cultivars to date. As such, research was conducted over four years in North Carolina to determine peanut stand, injury caused by tobacco thrips feeding, and pod yield as influenced by planting date (early, mid-, and late-May), fungicide seed treatment, and phorate applied in the seed furrow at planting. Peanut stand increased when planting fungicide-treated seed compared to non-treated seed, although the magnitude of this effect lessened with later May plantings. Regardless of phorate treatment, less thrips injury was noted when peanut was planted in mid- or late-May compared with early May in three of four years. Yet the addition of phorate in-furrow further reduced thrips injury at every planting date. Peanut yield increased 75% and 50% of the time when seed was treated with fungicide and phorate was applied in the seed furrow at planting, respectively. Yield was generally greater when peanut was planted in mid-May and late-May compared to planting in early May irrespective of fungicide seed treatment or phorate treatment. Peanut stand was negatively and positively correlated with observed thrips injury and peanut yield, respectively. Additionally, peanut yield was negatively correlated to thrips injury. These data suggest that conventional producers should utilize treated seed and phorate in-furrow for thrips management regardless of planting date and that organic producers should plant in late May to minimize negative impacts of thrips and soil borne pathogens.