Variability of ergovaline and total ergot alkaloid expression among endophytic tall fescue cultivars

Tall fescue (Lolium arundinaceum [Schreb.] Darbysh.) is one of the most widely grown grasses in the United States. Most plants are infected with an endophyte, Epichloë coenophiala Bacon and Schardl. This endophyte produces high concentrations of ergot alkaloids, which cause fescue toxicosis in livestock. The economic losses to the US livestock industry are estimated to be approximately $1 billion annually. The objectives were to evaluate the variability in total ergot alkaloid concentrations ([TEA]) and ergovaline concentrations ([E]) in leaf blades and sheaths, and whole tillers from cultivars containing different wild-type and novel endophytes across two seasons and environments. This study was conducted in 2012 and 2014 at two sites: Watkinsville, GA and Lexington, KY. There was no location effect for [TEA] or [E] in whole tillers. Measurements in 2012 showed no ergovaline-producing tillers for cultivars infected with MaxQ or MaxQ II. Cultivars BarOptima Plus E34 and IS-FTF 31-UArk9 produced tillers expressing ergovaline but at lesser levels than endophyte-infected KY 31. In leaf blades, [TEA] and [E] were greater in 2012 than 2014 at both sites for KY 31 (1861 and 402 vs. 1473 and 135 µg kg^–1, respectively). Large variability can occur in KY 31, BarOptima Plus E34, and IS-FTF 31-UArk9 for ergot alkaloid content over years, within seasons, and between cultivars. This research indicates the importance of testing fields for ergot alkaloid content to determine risk from grazing and hay feeding.