Effective morningglory control systems in Louisiana cotton normally utilize preemergence surface application of the maximum safe rate of fluometuron (Cotoran/Meturon) as the most important line of defense against these pernicious weeds. However, control is often incomplete because of inherent tolerance to fluometuron, failure to receive timely rainfall for herbicide activation, improper rate of application (especially in portions of fields that have higher than normal organic matter or clay content), or combinations of these factors. Control in high organic matter and high clay content areas of fields may be improved by spraying additional fluometuron before cotton emergence. A dinitroaniline herbicide or a combination of zorial plus a dinitroaniline herbicide preplant incorporated complements the activity of fluometuron on morningglories and provides control of other species. Timely postemergence directed sprays are an important component of effective management systems, and a number of effective herbicides are available. Proper timing of application and complete coverage are probably more important than material selection. Hand weeding is effectively used by many growers in trouble spots to keep morningglory problems from becoming unmanageable. Timely postemergence over-the-top treatments with fluometuron or fluometuron plus DSMA or MSMA are effective; however, they are used sparingly since they may be highly injurious to cotton.

These programs have allowed many growers to control morningglories adequately. In situations where current efforts are inadequate, cracking or pre-cracking applications of Gramoxone Extra or Roundup, perhaps coupled with a stale-bed planting technique that encourages emergence of one or more flushes of morningglories prior to cotton emergence, used in conjunction with the programs outlined above might be of value in bringing morningglory populations to manageable levels.