Greenhouse studies were conducted in Raleigh, NC to determine Carolina redroot control by selected PRE and POST herbicides labeled for blueberries. Paraquat, glufosinate, glyphosate, and flumioxazin provided some Carolina redroot shoot control 7 d after POST application (DAPOST) ranging from 48 to 74%. Control 25 DAPOST was greatest for hexazinone at 2.2 kg ai ha−1 (90%) followed by glufosinate with 56% control and paraquat and terbacil each with 53% control. Control for most treatments declined between 25 and 63 DAPOST with the exception of glyphosate, which increased to 64%. Carolina redroot shoots per pot were reduced by terbacil, hexazinone at 2.2 kg ha−1, and glyphosate compared with the nontreated check 63 DAPOST. Control of Carolina redroot roots and rhizomes 63 DAPOST ranged from 7 to 68%, with the greatest control provided by terbacil (68%) and hexazinone at 2.2 kg ha−1 (64%). Terbacil and hexazinone at 2.2 kg ha−1 were the only treatments that reduced both shoot and root/rhizome dry weight compared with the nontreated check.

Greenhouse studies were conducted in 2012 in Raleigh, NC to determine Carolina redroot control by ten POST herbicides. Paraquat and glufosinate provided the greatest control 14 (73 and 64%, respectively) and 25 d (82 and 68%, respectively) after treatment (DAT), but control declined between 25 and 63 DAT (72 and 59%, respectively). Glyphosate provided minimal control 14 DAT (18%), and control increased from 14 to 25 DAT (46%) and 25 to 63 DAT (69%). Control of Carolina redroot roots and rhizomes (roots/rhizomes) was greatest in plants treated with paraquat (91%), glyphosate (88%), glufosinate (73%), hexazinone (62%), diuron (60%). Nontreated Carolina redroot shoot and root/rhizome dry weight were 8.3 and 7.6 g, respectively. Paraquat, glufosinate, glyphosate, and diuron reduced both shoot and root/rhizome dry weight (3.1 and 0.7 g, 5.1 and 2.7 g, 5.4 and 1.0, 5.7 and 1.6 g, respectively). Hexazinone reduced root/rhizome dry weight (2.7 g). Fomesafen reduced shoot dry weight (6.1 g), but did not reduce root/rhizome dry weight. Paraquat, glufosinate, glyphosate, hexazinone, diuron, and clopyralid treatments resulted in reduced incidence of Carolina redroot flowering and anthesis.