Herbcide Options for Weed Escapes Peanut Notes No. 87 2019

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The combination of dry weather with limited herbicide activation and recent rains limiting field work likely will result in relatively large and diverse weed complexes that will need to be controlled. There are several options to select from. Here are some possibilities. Note that all of these are mixtures. Often a one-two punch is more effective than a single tank mix, but timing and logistics point to tank mixtures.

Gramoxone SL plus Basagran plus nonionic surfactant

We are almost past the window for this herbicide combination, but for late-planted peanut this can still work well. Applying this about 3 weeks after planting is better than waiting until 4 weeks after emergence. Sometimes we can kill large weeds with this but that is generally at a higher Gramoxone SL rate.

Cobra (12.5 oz/acre) or Ultra Blazer (24 oz/acre) plus 2,4-DB (8-16 oz/acre) plus nonionic surfactant or crop oil concentrate. (plus clethodim?)

This combination works well on pigweed, morningglory (better on pitted and tall than entireleaf or ivyleaf), eclipta, and common ragweed but will not control sicklepod, nutsedge, prickly sida, and common lambsquarters very well. Many fields contain annual grasses, and while we know these herbicides reduce grass control by clethodim-containing herbicides and Poast, increasing the rate of these grass herbicides to the maximum allowable rate for a single application can overcome much of the antagonism. Applying the grass herbicide first and then following up with the broadleaf herbicides 3 days later will work best, but most folks are not willing or able to make sequential applications. If a grass herbicide is included use crop oil concentrate rather than nonionic surfactant.

Cobra (12.5 oz/acre) or Ultra Blazer (24 oz/acre) plus 2,4-DB (8-16 oz/acre) plus Basagran (16-24 oz/acre) plus nonionic surfactant or crop oil concentrate. (plus clethodim?)

This is an expensive treatment but will control many of the weeds that Cobra and Ultra Blazer miss (see comments above on these herbicides.)  This combination often works well on common lambsquarters but will not control sicklepod completely. The PPO inhibitors and Basagran will certainly cause the grass herbicides to perform poorly, but using the higher end of the labeled rate of clethodim can partially overcome the antagonism, especially when weeds are small and not stressed. However, be ready for a follow up with a grass herbicide a few weeks after this combination is applied if control is incomplete.

Cadre or Impose (4 oz/acre) plus Cobra (12.5 oz/acre) or Ultra Blazer (24 oz/acre) plus nonionic surfactant or crop oil concentrate. (I am pointing out the higher rates of PPO inhibitors here, but in many cases 8 oz of Cobra and 16 oz Ultra Blazer can work well enough when applied with Cadre – but this all depends on weed size and frequency of ALS resistance, especially if Palmer amaranth and common ragweed are present)

This combination is also expensive but can provide control of many weeds in the field including sicklepod. A drawback is carryover to cotton from residues of Cade or Impose. But in fields where this is not an issue, this combination will do an excellent job controlling weeds that have emerged as well as many of those that will emerge.