Dr. Steve Li, extension specialist, gives farmers a few tips for weed control after peanuts have been planted.
The recent dicamba ban has seriously disrupted the weed control plan of many growers who want to use it. No new sales of Xtendimax, Engenia and FeXapan are allowed after the court ban on June 3. Two legal options for cotton and peanut growers are either contact the dealers who still have stock of Xtendimax, Engenia and FeXapan, and have them spray those for you, or secure Tavium from Syngenta although supply is running tight. I would suggest growers prioritize their application plan and save new dicamba for fields with highest pressure of Palmer and troublesome broadleaf weeds. Liberty can take care of most common weed species in cotton-peanut rotations when they are relatively small in size (less than 6 inches). It is also the best thing for volunteer peanut control. Using medium droplet size nozzles and at least 15 GAP output on a hot sunny day will produce the best control efficacy.
For late May planted peanuts that have run into serious weed problems, Gramoxone is a great option as long as it is sprayed within 28 days after cracking. I have recommended 12 oz of 3 lb Gramoxone + 16 oz of 24DB + a group 15 residual herbicide (either 16 oz of Dual Magnum/13 oz Outlook/2.5 oz Zidua SC, or 2.5 pt./Warrant) several times on peanut fields with lots of Palmer and sickle pod. I heard good results from a few growers who used them. If nutsedge (nutgrass) is a problem in a certain area, I recommend Dual Magnum 1.33 pt./A PRE + half rate of Strongarm, (3 lb. Gramoxone at 8 oz + a Group 15 residual around three weeks after planting is the best option if PRE is not activated well). Then around 30-40 DAP, spray Cadre 3 oz + Bentazon 1.5 pt. + Dual Magnum 1pt/A, or Storm 1.5 pt./A + Strongarm 0.225 oz/A (half rate) + Dual 1 pt./A where Palmer is also a problem. Cadre + Strongarm + 24DB is a good choice to clean up broadleaf weeds other than Palmer.
The addition of a crop oil surfactant will increase control of tough weeds as long as peanuts are younger than 40 DAP. I do not like using crop oil on bigger peanuts because of leaf burn. Use Group 15 residual at least once over the top of peanuts to prevent flush of annual grasses which often requires more expensive POST grass control herbicides such as clethodim and fluazifop. Spraying Select Max or Fusillade 2-3 times to control grass is not a wise or cheap idea. If tropical spiderwort is becoming a problem, I recommend using Dual or Warrant + half rate Strongarm PRE. Apply Gramoxone as needed before the cutoff date. Then Cadre + half rate Strongarm + Dual Magnum 1 pt./A around 30-40 DAP. We have seen very good results from this program in fields with heavy pressure.
Overall, the goal for weed control is by 60 DAP, you can put your herbicide jugs to sleep until next summer. For weed control and herbicide application, it is always better early than late!
If you have questions, please contact Steve Li at firstname.lastname@example.org.