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Agronomic Crops > Crops Blog > Posts > Mid-late Season Weed Problem in Peanut

Since mid-July, I have received several grower inquiries regarding mid-late season weed control in peanut.  Most of them were related to large morningglory, sicklepod, coffeeweed, pigweed, FL pusley, etc.  Growers wanted to know what options they can spray to control those weeds when their peanut is around 90 days old.  I hate to tell them use a bushhog to mow weeds down, but at this point, herbicide options are limited due to pre-harvest interval (PHI) restrictions on herbicide labels.  For example, a PHI of 90 days means that growers cannot apply this herbicide within 90 days before harvest. 

Late season morningglory infestation in Headland, AL peanut fieldIt is understandable that growers may have a few patches of weeds in mid-late season that they want to clean up.  However, if someone is in deep trouble with weeds when his peanut is at 90 days after planting, I believe that he did not use proper postemergence treatments early on in his crop.  Lack of residual herbicides in early postemergence treatments is a major cause for this problem.  Chloroacetamide herbicides such as Dual Magnum, Zidua, Outlook and Warrant applied at full label rate can usually provide 20-30 days of residual weed control and they are critical components to a successful season-long weed control program in peanut.

As a conclusion, for those who struggle with mid-late season weed problems in peanut:


  1. Check your postemergence treatments and include chloroacetamide residual herbicides with postemergence herbicides if you have not.
  2. Apply postemergence herbicides with short PHI and make sure you follow label restrictions.
  3. A weed wiper or roller will allow growers to wipe high rates of Gramoxone and other non-selective herbicides on weeds, however, it is a very slow process and may not work on large acreage.
  4. Bring your bushhog to the field. No weeds have developed resistance to a steel blade yet. If you cannot fully control them with herbicides, then at least do not let them set seeds and build up future problems for you.  

Steve Li

Extension Weed Scientist, Assistant Professor



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