Switchgrass Establishment and Biomass Yield Responses to Fungicide and Insecticide Seed Treatments

Abstract

Switchgrass (Panicum virgatum L.) is being evaluated for both forage and bioenergy in the Great Plains of the USA. Management strategies to improve switchgrass seedling vigor and emergence may result in more successful switchgrass stands due to better competitive advantage for switchgrass seedlings over weedy species. The objectives of this field experiment were to determine the effects of seven broad‐spectrum fungicide and insecticide seed treatments on the establishment and yield of lowland type ‘EG1101’ switchgrass. The combination of fungicide + insecticide (regardless of formulation) tended to result in taller seedlings and greater seedling densities and stands of switchgrass as compared to untreated control (UTC), fungicide only, and insecticide only. These advantages didn’t result in greater switchgrass dry matter (DM) yield, probably due to adequate stands (>1–2 plants per ft2) that were achieved by all fungicide–insecticide seed treatments including UTC. However, given the relatively small cost per acre of seed treatments, there may be early‐season benefits to treating seeds with a broad‐spectrum insecticide as an insurance measure to increase switchgrass seedling vigor and reduce the chance of stand failure, especially when used with a proven weed management program.