Vegetation Control for No‐Tillage Corn Planted into Warm‐Season Perennial Species

Abstract

The success of no‐tillage corn (Zea mays L.) planted into sod in the Southeast depends on control of warm‐season perennials. Preemergence (PRE) and postemergence (POST) herbicides were evaluated for control of warm‐season perennial and annual species in no‐tillage corn production. Vegetation spectrum differences at the various locations influenced both herbicide rate and timing of application required for 90% control by imazapyr {(±)‐2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐3‐pyridinecarboxylic acid}, imazethapyr {2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1 H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid}, glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl) butanoic acid], or imazapyr + imazethapyr. Imazapyr controlled established bermudagrass (Cynodon dactylon L.), broomsedge (Andropogon virginicus L.), johnsongrass [Sorghum halepense (L.) Pers.], tall fescue (Festuca arundinacea Schreb.), and dallisgrass (Paspalum dilatatum Poir.) in all instances. Several herbicides were used in selected combinations for PRE and/or POST applications in discrete rate trials. These were imazapyr, imazethapyr, glufosinate, imazapyr + imazethapyr, paraquat (1, 1′‐dimethyl‐4,4′‐bipyridinium ion), atrazine [6‐chloro‐N‐ethyl‐N1‐(1‐methyethyl)‐1,3,5‐triazine‐2,4‐diamine], and glyphosate [N‐(phosphonomethyl)glycine]. The glufosinate‐resistant corn hybrid in 1997 at Holly Springs, MS, with glyphosate PRE at 0.84 kg a.i. ha−1 followed by glufosinate POST (28 DAP) at 0.45 kg ha−1 produced a maximum yield of 10.2 Mg ha−1. Results from this study indicate that vegetation can be controlled for corn production in untilled sod comprised of warm‐season perennials when transgenic hybrids are grown.