Warm‐season Grass Establishment with Atrazine¹

Abstract

Weed competition is a limiting factor in warm‐season grass establishment often delaying the first forage harvest 2 or 3 years. Weed control with herbicides could reduce this competition resulting in more rapid grass establishment. Field experiments were conducted to evaluate the effect of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] on weed control, warm‐season grass establishment, and forage yield during the seeding and following year. Several warm‐season grass species were spring seeded at locations having distinctly different soils. The soils involved were a Butler silty clay loam (Abruptic Argiaquoll) containing 3.8% organic matter and a pH of 5.2, a Crofton silty clay loam (Typic Ustorthent) containing 2.1% organic matter with a pH of 7.2 and a Nora silty clay loam (Udic Haplustoll) containing 2.8% organic matter and pH 5.8. Atrazine at various rates was applied preemergence shortly after grass seeding and at one site it was atso applied the preceding fall. Weed control, grass establishment, and forage yield were measured the year of seeding and the following year. Uncontrolled weeds during the year of seeding reduced stands and 1st year forage yields of big bluestem (Andropogon gerardi Vitman), indiangrass [Sorghastrum nutans (L.) Nash], sand lovegrass [Eragrostis trichodes (Nutt.) Wood], sideoats grama [Bouteloua curtipendula (Michx.) Torr.], and switchgrass (Panicum virgatum L.). Big bluestem and switchgrass tolerated preemergence atrazine applications of 3.4 kg/ha on the Butler soil. Big bluestem was less tolerant of atrazine than switchgrass on the Crofton soil. Some atrazine tolerance was present in indiangrass but not in sand lovegrass and sideoats grama. Seeding year forage yields of big bluestem and switchgrass were significantly increased by atrazine. Weed control during the seeding year sometimes resulted in higher forage yields the following year. Big bluestem and switchgrass can he readily established and produce substantial forage yields the year of seeding by using atrazine for weed control. This would make these grasses more attractive to farmers and ranchers.

Herbicides for Establishing Switchgrass in the Central and Northern Great Plains

“…Atrazine has improved switchgrass establishment by controlling broadleaf weeds and C 3 (cool season) weedy grasses [1,5], but it has limited effectiveness for controlling warm-season annual grasses such as foxtails (Setaria spp.). Previous unpublished herbicide screening research by USDA-ARS in Lincoln, NE indicated that switchgrass establishment was improved by imazapic (Plateau \ ) application at 35 g a.i.…”

A Floristic Inventory and Vegetation Survey of Three Dolomite Prairies in Northeastern Illinois

“…Martin and Moomaw (1974) report excellent control of bluegrass from applications of 2 lb/a (2.24 kg/ha) glyphosate in spring while warm season grasses were dormant. Waller and Schmidt (1983) report significant decreases in the productivity of Poa pratensis along with increasing big bluestem production as a result of April 21 applications of 1 lb/a (1.12 kg ha) glyphosate on Poa-infested loams in southeastern Nebraska.…”

Sustainability Protocols and Certification Criteria for Switchgrass-Based Bioenergy

“…Sources: Martin et al 1982;Muir et al 2001;Vogel et al 2001;Vogel et al 2002;Hanson et al 2005;Fike et al 2006;Mulkey et al 2006;Cramer et al 2007;Lee et al 2007;Mitchell et al 2008;Mitchell et al 2012;NRDC 2014.…”