Redweed (Melochia corchorifolia) is a significant problem in cotton in extreme South Georgia. Probable reasons for it being a primary weed in many fields of this region include: 1) the ineffectiveness of preemergence broadleaf herbicides related to the lack of timely rainfall and 2) discontinued use of preemergence broadleaf herbicides because of poor control in recent years.

In 1987, studies were conducted at two locations near Moultrie, Georgia, to evaluate the response of redweed to various treatments, including preemergence and postemergence herbicide applications. Preemergence applications of diuron, fluometuron, norflurazon, and norflurazon combinations provided excellent (>95%) control of redweed. At both locations adequate or excessive rainfall occurred within a few hours after application, and thus the degree of control obtained in these experiments may exceed that which results under dry conditions.

In separate studies, postemergence directed treatments were evaluated in cotton 3 to 5 in. tall with redweed 2 to 9 in. in height. At the early treatment date, directed treatments of methazole + MSMA or fluometron + MSMA provided better than 90% control. Postemergence over-the-top and directed treatments of MSMA had little effect on redweed. At the later application date, redweed greater than 5 in. was difficult to control, in part due to poor coverage. combinations of cyanazine, diuron, or linuron with MSMA resulted in 70 to 78% control, while other treatments provided 40% or less control.