Question:

What is the best herbicide option for marestail (horesweed) control? What is the preplant interval for 2,4-D?

Jordan:

There needs to be an interval of 30 days between 2,4-D application and planting peanut. I have seen some labels state "or until residues have dissipated." Not sure how easily to measure that. With the expense of peanut seed, we really need to be careful about applying products that could impact peanut stand establishment. Liberty or generic glufosinate has good activity on marestail but this herbicide can be expensive. But there are no residue issues. We have to assume glyphosate resistance. Burndown rates of paraquat are often not completely adequate.

For contact herbicide like Liberty and paraquat, coverage is essential. Slowing down sprayer speed and using more water can help with coverage. If using nozzles that create large droplets (and are good for drift reduction,) control can be compromised because of coverage. But there are lots of acres to spray and there are often sensitive plants not too far from the fields being sprayed that we don't want to hurt.