Postemergence Control and Glyphosate Tolerance of Doveweed (Murdannia nudiflora)

Doveweed is a problematic weed of lawns and sod production, as well as golf course roughs, fairways, and tees. End-user reports of selective POST control options are inconsistent and control is often short-lived. In addition, inconsistent control with non-selective herbicides such as glyphosate is common. The goals of this research were: (1) evaluate selective POST doveweed control options in ‘Tifway’ hybrid bermudagrass turf; (2) compare efficacy of single vs. sequential applications of selective POST herbicides; (3) quantify doveweed tolerance to glyphosate; and (4) quantify recovery of foliar applied glyphosate following treatment with a C14-glyphosate solution. A single application of sulfentrazone + metsulfuron; thiencarbazone + iodosulfuron + dicamba or 2,4-D + MCPP + dicamba + carfentrazone; or thiencarbazone + foramsulfuron + halosulfuron provided >60% control 2 weeks after initial treatment (WAIT). A second application of these treatments 3 WAIT improved control 6 WAIT. Two applications of 2,4-D + MCPP + dicamba + carfentrazone or thiencarbazone + foramsulfuron + halosulfuron provided ~80% control 6 WAIT. Doveweed was tolerant to glyphosate application up to 5.68 kg ae ha-1. Absorption of ¹⁴C-glyphosate was compared between doveweed with cuticle intact, doveweed with a disturbed cuticle, and smooth crabgrass. ¹⁴C-glyphosate recovery from the leaf surface of doveweed plants with an intact cuticle was 93.6%. In comparison, ¹⁴C-glyphosate recovery from the leaf surface of doveweed plants with a disrupted cuticle and the leaf surface of crabgrass plants was 79.1 and 70.5%, respectively. Nomenclature: Bromoxynil; carfentrazone; dicamba; foramsulfuron; glyphosate; halosulfuron; iodosulfuron; mecoprop; metsulfuron; MSMA; quinclorac; sulfentrazone; thiencarbazone; 2,4-D; doveweed, Murdannia nudiflora (L.) Brenan; smooth crabgrass, Digitaria ischaemum (Schreb.) Schreb. ex Muhl.; ‘Tifway’ bermudagrass, Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy.