Evaluation of Herbicides for the Control of Yellow Nutsedge (Cyperus esculentus L.) and Johnsongrass (Sorghum halepense L.) Under Non-Crop Conditions

Yellow nutsedge (Cyperus esculentus L.) and Johnsongrass (Sorghum halepense (L.) Pers.) are two of the most difficult weeds to control mostly due to their asexual reproduction. Yellow nutsedge reproduces through underground tubers and Johnsongrass through rhizomes. In addition, Johnsongrass is a problematic weed because of its competitive nature due to its C4 carbon fixation pathway metabolism. It typically grows to 1.8 to 2.5 m tall and can severely reduce yields in corn, cotton, soybeans, and other crops. Two separate field studies were conducted in 2020 at the Delta Research and Extension Center in Stoneville, Mississippi to evaluate the effectiveness of various herbicides on yellow nutsedge and Johnsongrass control in a non-crop scenario. The experiments were conducted as randomized complete block designs with 7 and 11 herbicide treatments for yellow nutsedge and Johnsongrass, respectively. All treatments were replicated three times. Research plots were 4-m wide and 6-m long with 3-m alleys between replications. The 7 yellow nutsedge herbicide treatments consisted of trifloxysulfuron, bentazon, halosulfuron, halosulfuron + thifensulfuron, glyphosate, glufosinate, and paraquat. The 11 Johnsongrass herbicide treatments included clethodim, quizalofop, fluazifop, cyhalofop, fenoxaprop, pinoxaden, glufosinate, glyphosate, clethodim + glyphosate, glufosinate + clethodim, and glufosinate + clethodim + glyphosate. Glyphosate and halosulfuron + thifensulfuron provided only 77 and 72% control of yellow nutsedge by five-weeks after application (WAA). On the other hand, glyphosate, clethodim + glyphosate, glufosinate + clethodim, and glufosinate + clethodim + glyphosate provided 99 to 100% Johnsongrass control 4 WAA. Johnsongrass regrowth evaluation was assessed 3-weeks after the experimental area was mowed. Johnsongrass regrew in every herbicide treatment except for glyphosate which was the only treatment that provided 100% Johnsongrass control with no-regrowth.