Establishment Systems for Glyphosate-Resistant Alfalfa

Abstract

Glyphosate-resistant alfalfa offers new weed control options for alfalfa establishment. Field studies were conducted in 2004 and 2005 to determine the effect of establishment method and weed control method on forage production and alfalfa stand establishment. Seeding methods included clear seeding and companion seeding with oats. Herbicide treatments included glyphosate, imazamox, imazamox + clethodim, and no herbicide. Temporary stunting from the glyphosate treatments was observed (< 7%); however, injury did not reduce forage yield or stand density in 2004. No glyphosate injury was observed in 2005. Weed control with glyphosate was more consistent than with imazamox or imazamox + clethodim. In 2004, total seasonal forage yield, which consisted of alfalfa, weeds, and oats (in some treatments), was the highest where no herbicide was applied in the oat companion crop and was reduced where herbicides were applied in both establishment systems. In 2005, seeding method or weed control method did not affect tot...