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.